### Pagination example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using page and pageSize parameters for pagination.

```javascript
const posts = await broker.call("posts.list", { page: 3, pageSize: 10 });
```

--------------------------------

### Multiple populates example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of populating multiple fields.

```javascript
const posts = await broker.call("posts.find", { populate: ["author", "voters"] });
```

--------------------------------

### Get function example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the `get` function to mask a credit card number.

```javascript
{
    creditCardNumber: {
        type: "string", 
        // Mask the credit card number
        get: ({ value }) => value.replace(/(\d{4}-){3}/g, "****-****-****-")
    }
}
```

--------------------------------

### Searching example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using search and searchText parameters.

```javascript
const posts = await broker.call("posts.find", {
    search: "content",
    searchText: ["title", "content"]
});
```

--------------------------------

### Limit & offset example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using limit and offset parameters.

```javascript
const posts = await broker.call("posts.find", { limit: 10, offset: 50 });
```

--------------------------------

### Install Knex

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

Install the dependent library for the Knex adapter.

```bash
npm install knex@^1.0.1
```

--------------------------------

### Multiple scopes example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using multiple scopes.

```javascript
const posts = await broker.call("posts.find", { scope: ["onlyActive", "hasVotes"] });
```

--------------------------------

### Populate example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the populate parameter to include related data.

```javascript
const posts = await broker.call("posts.find", { populate: "author" });
```

--------------------------------

### Example

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

This example shows how to configure the Knex adapter with MSSQL and define the service settings.

```javascript
// posts.service.js
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService({
        adapter: {
            type: "Knex",
            options: {
                knex: {
                    client: "mssql",
                    connection: {
                        host: "127.0.0.1",
                        port: 1433,
                        user: "sa",
                        password: "Moleculer@Pass1234",
                        database: "moleculer",
                        encrypt: false
                    }
                }
            }
        }
    })],

    settings: {
        fields: {
            id: { type: "number", primaryKey: true, columnName: "_id", columnType: "integer" },
            title: { type: "string", required: true, max: 100, trim: true },
            content: { type: "string", columnType: "text" }
        }
    },

    async started() {
        const adapter = await this.getAdapter();
        await adapter.createTable();
    }
}
```

--------------------------------

### Using query example (simple)

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the query parameter with a simple object.

```javascript
const posts = await broker.call("posts.find", {
    query: {
        status: false
    }
});
```

--------------------------------

### Fields example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the fields parameter to select specific fields.

```javascript
const posts = await broker.call("posts.find", { fields: ["id", "title", "votes"] });
```

--------------------------------

### Install

Source: https://github.com/moleculerjs/database/blob/master/README.md

Install the @moleculer/database package and optionally @seald-io/nedb for prototyping.

```bash
npm i @moleculer/database @seald-io/nedb
```

--------------------------------

### Default value examples

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Examples demonstrating how to set default values for fields, including asynchronous functions.

```javascript
{
    votes: { type: "number", default: 0 },
    role: { type: "string", default: async ({ ctx }) => await ctx.call("config.getDefaultRole") }
    status: { type: "boolean", default: true },
}
```

--------------------------------

### Example with dependencies

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Demonstrates how to define service dependencies, which are other services the current service relies on.

```javascript
module.exports = {
    name: "posts",
    mixins: [DbService(/*...*/)],
    // Define the 'users' as dependency
    dependencies: ["users", "comments"],
    /* ... */
};
```

--------------------------------

### Count entities example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Get the number of entities by query.

```javascript
const postCount = await broker.call("posts.count");
```

--------------------------------

### Get an entity by ID example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Get an entity by ID.

```javascript
const post = await broker.call("posts.get", { id: "YVdnh5oQCyEIRja0" });
```

--------------------------------

### Using query example (complex)

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the query parameter with a more complex object including operators.

```javascript
const posts = await broker.call("posts.find", {
    query: {
        status: true,
        votes: {
            $gt: 5
        }
    }
});
```

--------------------------------

### Database/Server-based Tenancy Configuration Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example configuration for database/server-based multi-tenancy in Moleculer's Database Service, using `getAdapterByContext` to specify connection strings.

```javascript
// posts.service.js
module.exports = {
    name: "posts",
    mixins: [DbService({ adapter: "MongoDB" })],
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            title: { type: "string", required: true, min: 5 },
            content: { type: "string", required: true }
        }
    },

    methods: {
        getAdapterByContext(ctx, adapterDef) {
            const tenantId = ctx && ctx.meta.user.tenantId;
            if (!tenantId) throw new Error("Missing tenantId!");

            return [
                // cache key
                tenantId, 

                // Adapter options
                {
                    type: "MongoDB",
                    options: {
                        uri: `mongodb://127.0.0.1:27017/moleculer-demo--${tenantId}`,
                        collection: `posts`
                    }
                }
            ];
        }
    }
};
```

--------------------------------

### Example Schema

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Demonstrates various field types and configurations including shorthand formats.

```javascript
{
    id: { type: "string", primaryKey: true, columnName: "_id" },
    username: { type: "string" },
    age: "number", // Shorthand format
    dateOfBirth: { type: "date" },
    address: { type: "object", properties: {
        country: { type: "string", required: true },
        city: "string|required", // shorthand format
        street: { type: "string" }
        zip: { type: "number" }
    } },
    phones: { type: "array", items: "string" }
}
```

--------------------------------

### Storing with non-supported adapters - Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example showing how to set 'columnType' to 'string' for object fields when using non-SQL adapters.

```javascript
module.exports = {
    // ...
    settings: {
        fields: {
            address: {
                type: "object",
                // Set columnType to string because it will be converted to JSON string.
                columnType: "string",
                properties: {
                    // ...
                }
            }
        }
    }
};
```

--------------------------------

### onCreate hook example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the `onCreate` hook to set `createdAt` timestamp and `createdBy` user ID.

```javascript
{
    createdAt: {
        type: "number", 
        readonly: true, 
        onCreate: () => Date.now()
    },
    createdBy: {
        type: "string", 
        readonly: true,
        onCreate: ({ ctx }) => ctx.meta.user.id
    }
}
```

--------------------------------

### Scope example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the scope parameter to filter results.

```javascript
const posts = await broker.call("posts.find", { scope: "onlyActive" });
```

--------------------------------

### Call the actions

Source: https://github.com/moleculerjs/database/blob/master/README.md

Examples of calling various database actions like create, find, list, get, update, and remove using the Moleculer broker.

```javascript
// sample.js

// Create a new post
let post = await broker.call("posts.create", {
    title: "My first post",
    content: "Content of my first post..."
});
console.log("New post:", post);
/* Results:
New post: {
  id: 'Zrpjq8B1XTSywUgT',
  title: 'My first post',
  content: 'Content of my first post...',
  votes: 0,
  status: true,
  createdAt: 1618065551990
}
*/

// Get all posts
let posts = await broker.call("posts.find", { sort: "-createdAt" });
console.log("Find:", posts);

// List posts with pagination
posts = await broker.call("posts.list", { page: 1, pageSize: 10 });
console.log("List:", posts);

// Get a post by ID
post = await broker.call("posts.get", { id: post.id });
console.log("Get:", post);

// Update the post
post = await broker.call("posts.update", { id: post.id, title: "Modified post" });
console.log("Updated:", post);

// Delete a user
const res = await broker.call("posts.remove", { id: post.id });
console.log("Deleted:", res);
```

--------------------------------

### Table/Collection-based Tenancy Configuration Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example configuration for table/collection-based multi-tenancy in Moleculer's Database Service, demonstrating the `getAdapterByContext` method.

```javascript
// posts.service.js
module.exports = {
    name: "posts",
    mixins: [DbService({ adapter: "MongoDB" })],
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            title: { type: "string", required: true, min: 5 },
            content: { type: "string", required: true }
        }
    },

    methods: {
        getAdapterByContext(ctx, adapterDef) {
            const tenantId = ctx && ctx.meta.user.tenantId;
            if (!tenantId) throw new Error("Missing tenantId!");

            return [
                // cache key
                tenantId, 

                // Adapter options
                {
                    type: "MongoDB",
                    options: {
                        uri: "mongodb://127.0.0.1:27017/moleculer-demo",
                        collection: `posts-${tenantId}`
                    }
                }
            ];
        }
    }
};
```

--------------------------------

### Field Definitions Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

An example demonstrating how to define fields for a service using the Database Mixin, including various property types and configurations.

```javascript
// posts.service.js
module.exports = {
    // ...
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            title: { type: "string", required: true, max: 100, trim: true },
            content: { type: "string", columnType: "text" },
            votes: "number|integer", // Shorthand format
            status: { type: "boolean", default: true },
            createdAt: { type: "number", readonly: true, onCreate: () => Date.now() },
            updatedAt: { type: "number", readonly: true, onUpdate: () => Date.now() }
        }
    }
    // ...
}
```

--------------------------------

### Virtual field example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example demonstrating a virtual field that computes its value.

```javascript
{
    fullName: {
        type: "string",
        virtual: true,
        get: ({ entity }) => `${entity.firstName} ${entity.lastName}`
    }
}
```

--------------------------------

### Disable all default scopes example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of disabling all default scopes.

```javascript
const posts = await broker.call("posts.find", { scope: false });
```

--------------------------------

### Set function example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of using the `set` function to combine first and last names into a full name, and to convert email to lowercase.

```javascript
{
    firstName: { type: "string", required: true },
    lastName: { type: "string", required: true },
    fullName: {
        type: "string", 
        readonly: true,
        set: ({ params }) => `${params.firstName} ${params.lastName}`
    },
    email: { type: "string", set: value => value.toLowerCase() }
}
```

--------------------------------

### Immutable field example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example showing how to define an immutable field.

```javascript
{
    accountType: { type: "string", immutable: true }
}
```

--------------------------------

### Service Hooks - Adapter hooks example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

An example demonstrating the usage of 'adapterConnected' and 'adapterDisconnected' hooks within a service's custom hooks.

```javascript
// posts.service.js
{
    name: "posts",
    mixins: [DbService(/*...*/)],
    hooks: {
        customs: {
            adapterConnected: "createTables" // method name
            async adapterDisconnected(adapter, hash) {
                // ...
            }
        }
    },

    method: {
        async createTables(adapter, hash, adapterOpts) {
            // ...
        }
    }
}
```

--------------------------------

### Service Implementation Example

Source: https://github.com/moleculerjs/database/blob/master/CLAUDE.md

An example of how to implement a service using the @moleculer/database mixin.

```javascript
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService({ adapter: "MongoDB" })],
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            title: { type: "string", required: true },
            // ... more fields
        }
    }
}
```

--------------------------------

### Record-based Tenancy Configuration Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example configuration for record-based multi-tenancy in Moleculer's Database Service, including defining fields and scopes.

```javascript
// posts.service.js
module.exports = {
    name: "posts",
    mixins: [DbService({ adapter: "MongoDB" })],
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            title: { type: "string", required: true, min: 5 },
            content: { type: "string", required: true },
            tenantId: {
                type: "string",
                required: true,
                set: ({ ctx }) => ctx.meta.user.tenantId
            }
        },
        scopes: {
            tenant(q, ctx, params) {
                const tenantId = ctx.meta.user.tenantId;
                if (!tenantId) throw new Error("Missing tenantId!");

                q.tenantId = tenantId;
                return q;
            }
        },
        defaultScopes: ["tenant"]
    }
};
```

--------------------------------

### Sorting (one field) example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of sorting by a single field.

```javascript
const posts = await broker.call("posts.find", { sort: "createdAt" });
```

--------------------------------

### Sorting (multiple fields) example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of sorting by multiple fields, including descending order.

```javascript
const posts = await broker.call("posts.find", { sort: ["-votes", "title"] });
```

--------------------------------

### Create multiple entities

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of creating multiple post entities.

```javascript
const post = await broker.call("posts.createMany", [
    {
        title: "My first post",
        content: "Content of my first post..."
    },
    {
        title: "My second post",
        content: "Content of my second post..."
    }
]);
```

--------------------------------

### Custom actions example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of defining custom actions like voteUp and voteDown in a Moleculer service.

```javascript
// posts.service.js
module.exports = {
    // ...
    actions: {
        voteUp: {
            rest: "POST /:id/vote-up",
            params: {
                id: "string|required"
            },
            handler(ctx) {
                const entity = this.resolveEntity(ctx, params);
                return this.updateEntity(ctx, {
                    id: ctx.params.id,
                    votes: entity.votes + 1
                });
            }
        },

        voteDown: {
            rest: "POST /:id/vote-down",
            params: {
                id: "string|required"
            },
            handler(ctx) {
                const entity = this.resolveEntity(ctx, params);
                return this.updateEntity(ctx, {
                    id: ctx.params.id,
                    votes: entity.votes - 1
                });
            }
        }
    }
    // ...
}
```

--------------------------------

### Example with authority

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Demonstrates how to implement the `checkScopeAuthority` method in a service to control access based on user roles.

```javascript
// posts.service.js
module.exports = {
    name: "posts",
    mixins: [DbService(/*...*/)],
    settings: {
        /* ... */
    },

    methods: {
        /**
         * Check the scope authority. Should be implemented in the service.
         *
         * @param {Context} ctx
         * @param {String} name
         * @param {String} operation
         * @param {Object} scope
         */        
        async checkScopeAuthority(ctx, name, operation, scope) {
            // We enable default scope disabling only for administrators.
            if (operation == "remove") {
                return ctx.meta.user.roles.includes("admin");
            }

            // Enable all other scopes for everybody.
            return true;
        },  
    }
};
```

--------------------------------

### Example Valid Data

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Shows a valid data object conforming to the example schema.

```javascript
{
    id: "abc123",
    username: "John Doe",
    age: 34,
    dateOfBirth: new Date(),
    address: {
        country: "UK",
        city: "London",
        street: "Main Street 156",
        zip: 12345
    },
    phones: ["555-1234", "555-9876"]
}
```

--------------------------------

### REST endpoint for find

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

GET /{serviceName}/all

```javascript
GET /{serviceName}/all
```

--------------------------------

### Install MongoDB driver

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/MongoDB.md

Command to install the MongoDB driver using npm.

```bash
npm install mongodb@^4.1.4
```

--------------------------------

### Handle the Stream response

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of how to consume the stream response and collect data.

```javascript
const rows = [];

const ss = await broker.call("posts.findStream");

ss.on("data", row => rows.push(row));
ss.on("end", () => {
    console.log("Received all entities via stream:", rows)
});
```

--------------------------------

### Create a single entity

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of creating a single post entity.

```javascript
const post = await broker.call("posts.create", {
    title: "My first post",
    content: "Content of my first post..."
});
```

--------------------------------

### Results for find

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of the results returned by the find action.

```javascript
[
    {
        id: "akTRSKTKzGCg9EMz",
        title: "Third post",
        content: "Content of my 3rd post...",
        votes: 0,
        status: false,
        createdAt: 1618077045354,
    },
    {
        id: "0YZQR0oqyjKILaRn",
        title: "My second post",
        content: "Content of my second post...",
        votes: 3,
        status: true,
        createdAt: 1618077045352,
    }
]
```

--------------------------------

### Raw update example

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

Example of using the `updateEntity` method with `{ raw: true }` options for raw updates, including $set and $inc operators.

```javascript
const row = await this.updateEntity(ctx, {
    id: "YVdnh5oQCyEIRja0",

    $set: {
        status: false,
        height: 192
    },
    $inc: {
        age: 1
    }
}, { raw: true });
```

--------------------------------

### Install NeDB dependency

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/NeDB.md

Install the NeDB dependent library using npm.

```bash
npm install @seald-io/nedb
```

--------------------------------

### Example User-Defined Primary Key

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Shows how to define a primary key that is generated by the user, not the database.

```javascript
{
    id: { type: "string", primaryKey: true, generated: "user", columnName: "_id" }
}
```

--------------------------------

### REST endpoint for list

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

GET /{serviceName}/

```javascript
GET /{serviceName}/
```

--------------------------------

### afterResolveEntities Hook Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of how to use the `afterResolveEntities` hook in a Moleculer service to check entity statuses or permissions.

```javascript
// posts.service.js
{
    name: "posts",
    mixins: [DbService(/*...*/)],
    hooks: {
        customs: {
            async afterResolveEntities(ctx, id, rawEntity, params, opts) {
                // ...
            }
        }
    }
}
```

--------------------------------

### Connect to MySQL database

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

Example of connecting to a MySQL database using the Knex adapter.

```javascript
// posts.service.js
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService({
        adapter: {
            type: "Knex",
            options: {
                knex: {
                    client: "pg",
                    connection: {
                        host: "127.0.0.1",
                        user: "root",
                        password: "pass1234",
                        database: "moleculer"
                    }
                }
            }
        }
    })]
}
```

--------------------------------

### Results for list

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of the results returned by the list action, including pagination details.

```javascript
{
    rows: [
        {
            id: "2bUwg4Driim3wRhg",
            title: "Third post",
            content: "Content of my 3rd post...",
            votes: 0,
            status: false,
            createdAt: 1618077609105,
        },
        {
            id: "Di5T8svHC9nT6MTj",
            title: "My second post",
            content: "Content of my second post...",
            votes: 3,
            status: true,
            createdAt: 1618077609103,
        },
        {
            id: "YVdnh5oQCyEIRja0",
            title: "My first post",
            content: "Content of my first post...",
            votes: 0,
            status: true,
            createdAt: 1618077608593,
        },
    ],
    total: 3,
    page: 1,
    pageSize: 10,
    totalPages: 1,
}
```

--------------------------------

### Connect to PostgreSQL database

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

Example of connecting to a PostgreSQL database using the Knex adapter.

```javascript
// posts.service.js
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService({
        adapter: {
            type: "Knex",
            options: {
                knex: {
                    client: "pg",
                    connection: "postgres://postgres@localhost:5432/moleculer"
                }
            }
        }
    })]
}
```

--------------------------------

### Example Custom Column Name

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Shows how to map a field name to a different column name in the database.

```javascript
{
    id: { type: "string", primaryKey: true, columnName: "_id" },
    fullName: { type: "string", columnName: "full_name" }
}
```

--------------------------------

### Replace an entity

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of replacing an existing post entity.

```javascript
const post = await broker.call("posts.update", {
    id: "YVdnh5oQCyEIRja0",
    title: "Replaced title",
    content: "Content of my first post...",
    votes: 10,
    status: true,
    createdAt: 1618077608593,
    updatedAt: 1618082167005
});
```

--------------------------------

### Raw update example

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/MongoDB.md

Example demonstrating how to perform a raw update using MongoDB update operators with the updateEntity method.

```javascript
const row = await this.updateEntity(ctx, {
    id: "YVdnh5oQCyEIRja0",

    $set: {
        status: false,
        height: 192
    },
    $inc: {
        age: 1
    },
    $unset: {
        dob: true
    }
}, { raw: true });
```

--------------------------------

### Connect to MSSQL database

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

Example of connecting to an MSSQL database using the Knex adapter.

```javascript
// posts.service.js
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService({
        adapter: {
            type: "Knex",
            options: {
                knex: {
                    client: "mssql",
                    connection: {
                        host: "127.0.0.1",
                        port: 1433,
                        user: "sa",
                        password: "Moleculer@Pass1234",
                        database: "moleculer",
                        encrypt: false
                    }
                }
            }
        }
    })]
}
```

--------------------------------

### Example Custom Column Type

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Illustrates how to specify a database-specific column type for a field.

```javascript
{
    age: { type: "number", columnType: "integer" },
    lastLogin: { type: "date", columnType: "datetime" },
    createdAt: { type: "number", columnType: "bigInteger" }
}
```

--------------------------------

### Example for an array with objects

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Defines an array field 'phones' where each item is an object with phone details.

```javascript
module.exports = {
    // ...
    settings: {
        fields: {
            phones: {
                type: "array",
                items: {
                    type: "object",
                    properties: {
                        type: { type: "string" },
                        number: { type: "string", required: true },
                        primary: { type: "boolean", default: false }
                    }
                }
            }
        }
    }
};
```

--------------------------------

### Example Required Field

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Illustrates how to define a required field in the schema.

```javascript
{
    title: { type: "string", required: true }
}
```

--------------------------------

### Update an entity

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of updating an existing post entity.

```javascript
const post = await broker.call("posts.update", {
    id: "YVdnh5oQCyEIRja0",
    title: "Modified title",
    votes: 3
});
```

--------------------------------

### Example for string array

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Defines an array field 'roles' that accepts strings and has a maximum length of 3.

```javascript
module.exports = {
    // ...
    settings: {
        fields: {
            roles: {
                type: "array",
                max: 3,
                items: { type: "string" }
            }
        }
    }
};
```

--------------------------------

### Example Primary Key Field

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Defines a field as the primary key with a custom column name.

```javascript
{
    id: { type: "string", primaryKey: true, columnName: "_id" }
}
```

--------------------------------

### Get an entity by ID with different primary key field example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Get an entity by ID using a different primary key field.

```javascript
const post = await broker.call("posts.get", { key: "YVdnh5oQCyEIRja0" });
```

--------------------------------

### In-memory NeDB adapter usage

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/NeDB.md

Example of using the NeDB adapter in memory, which is the default configuration and requires no specific setup.

```javascript
// posts.service.js
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService()]
}
```

--------------------------------

### Connect to SQLite memory database

Source: https://github.com/moleculerjs/database/blob/master/docs/adapters/Knex.md

Example of connecting to an SQLite memory database using the Knex adapter.

```javascript
// posts.service.js
const DbService = require("@moleculer/database").Service;

module.exports = {
    name: "posts",
    mixins: [DbService({
        adapter: {
            type: "Knex",
            options: {
                knex: {
                    client: "sqlite3",
                    connection: {
                        filename: ":memory:"
                    },
                    useNullAsDefault: true
                }
            }
        }
    })]
}
```

--------------------------------

### Example with custom cache clearing event names

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Shows how to specify exact event names for cache clearing when dependencies change.

```javascript
module.exports = {
    name: "posts",
    mixins: [DbService({
        cacheCleanOnDeps: [
            "user.created",
            "cache.clean.comments",
            "my.some.event"
        ]
    })],
    /* ... */
};
```

--------------------------------

### Custom validation function example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of a custom validation function for a field.

```javascript
{
    username: {
        type: "string",
        validate: ({ value }) => /^[a-zA-Z0-9]+$/.test(value) || "Wrong input value"
    }
}
```

--------------------------------

### Hidden field examples

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Examples illustrating the use of the 'hidden' property for fields.

```javascript
{
    name: { type: "string" },
    password: { type: "string", min: 8, hidden: true },
    createdAt: { type: "number", hidden: "byDefault" }
}
```

```javascript
const res = broker.call("users.find", {
    fields: ["name", "password"]
})
```

```javascript
const res = broker.call("users.find", {
    fields: ["name", "createdAt", "password"]
})
```

--------------------------------

### Populate Fields Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Demonstrates various ways to configure field population in MoleculerJS services, including shorthand, parameterized, virtual fields, and custom handlers.

```javascript
module.exports = {
    // ...
    settings: {
        fields: {
            // Shorthand populate, only set the action name.
            voters: {
                type: "array", 
                items: "string",
                populate: "users.resolve" 
            },

            // Define the action name and the params. It will resolve the `username` and `fullName` of the author.
            author: {
                type: "string",
                populate: {
                    action: "users.resolve",
                    params: {
                        fields: ["username", "fullName"]
                    }
                }
            },

            // In this case the ID is in the `reviewerID` field.
            // But we create a `reviewer` virtual field which contains the populated reviewer entity.
            reviewer: {
                type: "object",
                virtual: true,
                populate: {
                    action: "users.resolve",
                    keyField: "reviewerID",
                    params: {
                        fields: ["name", "email", "avatar"]
                    },
                    callOptions: {
                        timeout: 3000
                    }
                }
            },
            

            // Custom populate handler function for a virtual field
            postCount: {
                type: "number",
                virtual: true,
                populate: (ctx, values, entities, field) => {
                    return Promise.all(
                        entities.map(async entity =>
                            entity.postCount = await ctx.call("posts.count", { query: { authorID: entity.id } });
                        )
                    );
                }
            }
        },

        // Default populates that are always populated
        defaultPopulates: ["author", "postCount"]
    }
    // ...
}
```

--------------------------------

### Example Secure ID using Hashids

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Demonstrates how to implement secure (encrypted) IDs using the hashids library.

```javascript
const Hashids = require("hashids/cjs");
const hashids = new Hashids("this is my salt");

module.exports = {
    name: "posts",
    mixins: [DbService()],

    settings: {
        fields: {
            id: { type: "string", primaryKey: true, secure: true, columnName: "_id" },
            // ... more fields
        }
    },
    
    methods: {
        encodeID(id) {
            return id != null ? hashids.encodeHex(id) : id;
        },

        decodeID(id) {
            return id != null ? hashids.decodeHex(id) : id;
        }
    }
}
```

--------------------------------

### Posts service example for cascade delete

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Demonstrates subscribing to the 'users.removed' event to implement cascade delete for posts associated with a deleted user.

```javascript
module.exports = {
    name: "posts",
    mixins: [DbService(/*...*/)],
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            title: { type: "string" },
            content: { type: "string" },
            author: { type: "string", required: true }
        }
    },

    events: {
        async "users.removed"(ctx) {
            const user = ctx.params.data;
            const adapter = await this.getAdapter(ctx);
            await adapter.removeMany({ author: user.id });
            this.logger.info(`The ${user.name} user's posts removed.`);
        }
    }
};
```

--------------------------------

### Raw updating example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Shows how to perform a raw update on an entity using the `updateEntity` method with the `raw: true` option, allowing direct database client parameter passing.

```javascript
const row = await this.updateEntity(ctx, {
    id: docs.johnDoe.id,

    $set: {
        status: false,
        height: 192
    },
    $inc: {
        age: 1
    },
    $unset: {
        dob: true
    }
}, { raw: true });
```

--------------------------------

### Permissions Example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Illustrates how to define field-level read and write permissions in MoleculerJS services and implement the `checkFieldAuthority` method for custom authorization logic.

```javascript
// users.service.js
module.exports = {
    name: "users",
    mixins: [DbService(/*...*/)],
    settings: {
        fields: {
            id: { type: "string", primaryKey: true, columnName: "_id" },
            name: { type: "string" },
            // Only the administrators can receives this field in responses.
            email: { type: "email", readPermission: "admin" },
            // Only the administrators can read & write this field.
            verified: { type: "boolean", permission: "admin" }
        }
    },

    methods: {
        // If we defined the necessary permissions in the fields, we should write 
        // the permission checking logic into the `checkFieldAuthority` method.
        async checkFieldAuthority(ctx, permission, params, field) {
            const roles = ctx.meta.user.roles || [];

            // Returns `true` if the logged in user's role field contains the required role.
            return roles.includes(permission);
        }
    }
}
```

--------------------------------

### Example: Fields for soft delete with onReplace hook

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Illustrates how to define fields for soft deletion using the onReplace hook.

```javascript
{
    removeAt: {
        type: "number",
        readonly: true,
        onReplace: () => Date.now()
    },
    removeBy: {
        type: "string",
        readonly: true,
        onReplace: ({ ctx }) => ctx.meta.user.id
    }
}
```

--------------------------------

### Delete an entity

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Example of deleting a post entity by ID.

```javascript
const post = await broker.call("posts.delete", { id: "YVdnh5oQCyEIRja0" });
```

--------------------------------

### Resolve entities by multiple IDs example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Resolve entities based on multiple IDs.

```javascript
const post = await broker.call("posts.resolve", { id: ["YVdnh5oQCyEIRja0", "Di5T8svHC9nT6MTj"] });
```

--------------------------------

### Resolve an entity by a single ID example

Source: https://github.com/moleculerjs/database/blob/master/docs/README.md

Resolve an entity based on a single ID.

```javascript
const post = await broker.call("posts.resolve", { id: "YVdnh5oQCyEIRja0" });
```