### Quick Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据模拟压测（DataSimulation）.md

A quick example demonstrating how to use DataSimulation to run a load test and print the TPS.

```csharp
var sim = new DataSimulation<Order>
{
    Threads = Environment.ProcessorCount,
    BatchSize = 2000,
    UseSql = false,
    Log = XTrace.Log
};

sim.Run(100_000);
Console.WriteLine($"TPS={sim.Score:n0}");
```

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

### Multi-role Permission Merging Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据权限.md

Example demonstrating how permissions are merged when a user has multiple roles.

```csharp
// 假设用户有两个角色：
// 角色A：DataScope = 仅本人 (3)
// 角色B：DataScope = 本部门及下级 (1)

// 最终权限 = Min(3, 1) = 本部门及下级
```

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

### Dynamic Database Sharding Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode数据模型与结构同步.md

C# code example showing how to select a database shard based on a user ID and then switch the connection.

```csharp
// 根据用户 ID 选择分库
var shardIndex = userId % 4;
var connName = $"Shard_{shardIndex:D2}";  // Shard_00 ~ Shard_03

// 切换连接
User.Meta.ConnName = connName;
```

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

### Typical Usage

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/字段缓存FieldCache.md

Example demonstrating how to initialize and use FieldCache to get a dictionary of field values and their counts.

```csharp
var fc = new FieldCache<User>("RoleID")
{
    MaxRows = 20,
    GetDisplay = e => e["RoleName"] + "",
};

var dic = fc.FindAllName();
// 结果：{"1":"管理员 (120)", "2":"访客 (56)"}
```

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

### Entity Metadata Examples

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode使用手册.md

C# code examples demonstrating how to access entity metadata such as type, table information, fields, and session.

```csharp
// Get entity type
var type = User.Meta.ThisType;

// Get table information
var table = User.Meta.Table;
var tableName = User.Meta.TableName;
var connName = User.Meta.ConnName;

// Get field information
var fields = User.Meta.Fields;
var allFields = User.Meta.AllFields;
var unique = User.Meta.Unique;
var master = User.Meta.Master;

// Get session
var session = User.Meta.Session;
var count = User.Meta.Count;
```

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

### Soft Delete Persistence Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体持久化接口与默认实现（IEntityPersistence）.md

Example of a custom persistence implementation for soft deletion.

```csharp
public class SoftDeletePersistence : EntityPersistence
{
    public SoftDeletePersistence(IEntityFactory factory) : base(factory) { }

    public override Int32 Delete(IEntitySession session, IEntity entity)
    {
        // 软删除：改状态字段，不做物理删除
        return Update(session,
            new[] { "IsDeleted", "UpdateTime" },
            new Object[] { true, DateTime.Now },
            new[] { "Id" },
            new Object[] { entity["Id"]! });
    }
}
```

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

### Dynamic Table Sharding Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode数据模型与结构同步.md

C# code example demonstrating how to dynamically set a table name based on the current month for monthly sharding and ensuring the table exists using the migration mode.

```csharp
// 按月分表
var tableName = $"Log_{DateTime.Now:yyyyMM}";  // Log_202602

// 修改 IDataTable
var dt = TableItem.Create(typeof(Log)).DataTable;
dt.TableName = tableName;

// 确保表存在
DAL.Create("Main").SetTables(Migration.OnlyCreate, dt);
```

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

### UserBehaviorMiddleware Core Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/ASP.NET Core行为监测迁移指南.md

A simplified C# example of the UserBehaviorMiddleware for ASP.NET Core, demonstrating how to capture request timing, SQL counts, and user behavior data.

```csharp
public class UserBehaviorMiddleware
{
    private readonly RequestDelegate _next;

    public UserBehaviorMiddleware(RequestDelegate next) => _next = next;

    public async Task Invoke(HttpContext ctx)
    {
        var begin = DateTime.Now;
        var q1 = DAL.QueryTimes;
        var e1 = DAL.ExecuteTimes;
        Exception? ex = null;

        try
        {
            await _next(ctx).ConfigureAwait(false);
        }
        catch (Exception err)
        {
            ex = err;
            throw;
        }
        finally
        {
            var cost = (Int32)(DateTime.Now - begin).TotalMilliseconds;
            var page = NormalizePath(ctx.Request.Path);
            var ip = GetIP(ctx);
            var user = ctx.User?.Identity?.Name;

            var model = new VisitStatModel
            {
                Time = DateTime.Now,
                Page = page,
                Title = page,
                Cost = cost,
                User = user,
                IP = ip,
                Error = ex?.Message
            };

            VisitStat.Process(model, StatLevels.Day, StatLevels.Month, StatLevels.Year);

            var q = DAL.QueryTimes - q1;
            var c = DAL.ExecuteTimes - e1;
            ctx.Response.Headers["X-DbRuntime"] = $"Q={q};E={c};Cost={cost}ms";
        }
    }

    private static String NormalizePath(PathString path)
    {
        var p = path.Value + "";
        return p;
    }

    private static String GetIP(HttpContext ctx)
    {
        var ip = ctx.Request.Headers["X-Forwarded-For"].FirstOrDefault();
        if (ip.IsNullOrEmpty()) ip = ctx.Request.Headers["X-Real-IP"].FirstOrDefault();
        if (ip.IsNullOrEmpty()) ip = ctx.Connection.RemoteIpAddress + "";
        return ip + "";
    }
}
```

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

### Install NewLife.Templates and create a new project

Source: https://github.com/newlifex/newlife.xcode/blob/master/Readme.MD

Install NewLife.Templates and create a new project using the xcode template.

```bash
dotnet new install NewLife.Templates
dotnet new xcode --name Demo.Data
cd Demo.Data
dotnet build
```

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

### Typical Usage

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/配置中心DbConfigProvider.md

Example demonstrating how to initialize and use DbConfigProvider.

```csharp
var provider = new DbConfigProvider
{
    UserId = 0,
    Category = "MyApp",
    CacheLevel = ConfigCacheLevel.Json,
    Period = 15,
};

Config.SetProvider(provider);
provider.LoadAll();
provider.Bind(MySetting.Current, autoReload: true);
```

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

### Quick Time Period Methods - Day Examples

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/字段时间区间扩展（FieldExtension）.md

Examples of using quick time period methods for days, such as Today() and LastDays(n).

```csharp
Order.FindAll(_.CreateTime.Today())       // Orders today
Order.FindAll(_.CreateTime.LastDays(7))  // Last 7 days
```

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

### Line Protocol Format Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/InfluxDB支持说明.md

Examples demonstrating the Line Protocol format for writing data.

```csharp
// Basic example
"temperature value=23.5"

// With tags
"temperature,location=room1,sensor=sensor1 value=23.5"

// Multiple fields
"temperature,location=room1 value=23.5,humidity=45"

// With timestamp (nanoseconds)
var nanos = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds() * 1000000;
$"temperature,location=room1 value=23.5 {nanos}"
```

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

### Registering UserInterceptor

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体拦截器（IEntityInterceptor）.md

Example of registering the UserInterceptor.

```csharp
Meta.Modules.Add<UserInterceptor>();
```

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

### Registering IPInterceptor

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体拦截器（IEntityInterceptor）.md

Example of registering the IPInterceptor.

```csharp
Meta.Modules.Add<IPInterceptor>();
```

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

### Flux Query Language Examples

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/InfluxDB支持说明.md

Examples of Flux queries for different data retrieval scenarios.

```csharp
// 1. Query data from the last 1 hour
var flux = @"
from(bucket: \"my-bucket\")
  |> range(start: -1h)
";

// 2. Filter by measurement
var flux = @"
from(bucket: \"my-bucket\")
  |> range(start: -1h)
  |> filter(fn: (r) => r._measurement == \"temperature\")
";

// 3. Filter by tag
var flux = @"
from(bucket: \"my-bucket\")
  |> range(start: -1h)
  |> filter(fn: (r) => r._measurement == \"temperature\")
  |> filter(fn: (r) => r.location == \"room1\")
";

// 4. Aggregation query (average)
var flux = @"
from(bucket: \"my-bucket\")
  |> range(start: -1h)
  |> filter(fn: (r) => r._measurement == \"temperature\")
  |> aggregateWindow(every: 5m, fn: mean)
";

// 5. Limit the number of results
var flux = @"
from(bucket: \"my-bucket\")
  |> range(start: -1h)
  |> limit(n: 100)
";
```

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

### Manual Module Upgrade Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/XCode/Code/EntityBuilder模块名称升级说明.md

Example of manually configuring EntityBuilder for module upgrades.

```csharp
var builder = new EntityBuilder
{
    AllTables = tables,
    Option = option,
    Log = log,
    EnableUpgradeModuleNames = true  // 手动开启升级
};

builder.Load(table);
builder.Business = true;
builder.Execute();
builder.Save(null, false, chineseFileName);
```

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

### Registering TraceInterceptor

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体拦截器（IEntityInterceptor）.md

Example of registering the TraceInterceptor.

```csharp
Meta.Modules.Add<TraceInterceptor>();
```

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

### Entity Class Operations: Query

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode使用手册.md

Examples of querying entity objects.

```csharp
// 按主键查询
var user = User.FindByKey(1);
var user = User.FindByKey(1, "Id,Name");  // 指定返回字段

// 按条件查询单个
var user = User.Find(User._.Name == "test");
var user = User.Find(User._.Status == 1 & User._.Enable == true);

// 查询列表
var list = User.FindAll();
var list = User.FindAll(User._.Status == 1);
var list = User.FindAll(User._.Status == 1, User._.Id.Desc(), null, 0, 10);

// 异步查询
var user = await User.FindAsync(User._.Id == 1);
var list = await User.FindAllAsync(User._.Status == 1);
```

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

### 插入处理模块

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/ETL数据转换.md

Example of inserting a custom processing module into the ETL pipeline.

```csharp
etl.Module = new MyFilterModule();
```

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

### Supported csproj Formats

Source: https://github.com/newlifex/newlife.xcode/blob/master/XCode/Code/EntityBuilder模块名称升级说明.md

Examples of supported csproj formats for PackageReference.

```xml
<!-- 格式1：直接在 PackageReference 中 -->
<PackageReference Include="NewLife.XCode" Version="11.23.2026.127-beta0417" />

<!-- 格式2：通过子元素指定 -->
<PackageReference Include="NewLife.XCode">
  <Version>11.23.2026.127-beta0417</Version>
</PackageReference>
```

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

### Create Model (db.xml)

Source: https://github.com/newlifex/newlife.xcode/blob/master/Readme.MD

Example of creating a model definition in db.xml.

```xml
<?xml version="1.0" encoding="utf-8"?>
<Tables Version="1.0" Output="MyEntity" NameSpace="Model" BaseClass="Entity" ConnName="DB">
  <Table Name="UserInfo" Description="用户信息">
    <Columns>
      <Column Name="Id" DataType="Int32" Identity="True" PrimaryKey="True" Description="会员id" />
      <Column Name="UserName" DataType="String" Nullable="False" Description="会员名称" />
      <Column Name="Password" DataType="String" Nullable="False" Description="会员密码" />
      <Column Name="Age" DataType="Int32" Description="会员年龄" />
    </Columns>
  </Table>
</Tables>
```

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

### 统计信息访问

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/ETL数据转换.md

Example of accessing the statistics object to get processing counts.

```csharp
var stat = etl.Stat;
Console.WriteLine($"成功={{stat.Success}} 错误={{stat.Error}}");
```

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

### Scenario 3: Single Tenant Deployment (Startup Configuration)

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/TableItem启动配置.md

Configuration example for permanently specifying the tenant database connection during startup for a single-tenant deployment.

```csharp
public class SingleTenantConfig
{
    public static void Configure(String tenantId)
    {
        // 整个应用只服务一个租户，启动时永久指定租户数据库
        var connName = $"Tenant_{tenantId}";
        
        User.Meta.Table.ConnName = connName;
        Order.Meta.Table.ConnName = connName;
        Product.Meta.Table.ConnName = connName;
        
        DAL.WriteLog("已为单租户 {0} 配置数据库连接：{1}", tenantId, connName);
    }
}
```

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

### Read-Only (No Refresh)

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体扩展字典（EntityExtend）.md

Example of getting a cached value without triggering a refresh if it doesn't exist.

```csharp
// 不传 func，只读当前缓存值，不存在时返回 null
var cached = Extends.Get<String>(nameof(RoleName));
```

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

### Common Access Methods

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/脏数据跟踪机制（DirtyCollection）.md

Examples of how to check if a field is dirty, enumerate dirty fields, and get a dictionary of old values.

```csharp
// 判断字段是否为脏
var changed = entity.Dirtys[User._.RoleId.Name];

// 枚举所有脏字段
foreach (var name in entity.Dirtys)
{
    Console.WriteLine(name);
}

// 获取字段旧值字典
var olds = entity.Dirtys.GetDictionary();
```

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

### Scenario 2: Sharding Strategy (Startup Configuration)

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/TableItem启动配置.md

Configuration example for distributing tables to different databases based on business modules during startup.

```csharp
public class ShardingConfig
{
    public static void Configure()
    {
        // 按业务模块分配到不同数据库
        User.Meta.Table.ConnName = "UserDB";
        Order.Meta.Table.ConnName = "OrderDB";
        Product.Meta.Table.ConnName = "ProductDB";
        Log.Meta.Table.ConnName = "LogDB";
        
        DAL.WriteLog("已配置分库策略");
    }
}
```

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

### Scenario 1: Table Prefix Scene (Startup Configuration)

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/TableItem启动配置.md

Configuration example for applying a uniform prefix to all table names during startup.

```csharp
public class TablePrefixConfig
{
    public static void Configure(String prefix)
    {
        // 为所有表添加统一前缀
        User.Meta.Table.TableName = $"{prefix}_{User.Meta.TableName}";
        Order.Meta.Table.TableName = $"{prefix}_{Order.Meta.TableName}";
        Product.Meta.Table.TableName = $"{prefix}_{Product.Meta.TableName}";
        
        DAL.WriteLog("已为所有表配置前缀：{0}", prefix);
    }
}
```

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

### Install

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/InfluxDB支持说明.md

Install the NewLife.XCode package using the .NET CLI.

```bash
dotnet add package NewLife.XCode
```

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

### ShowIn Syntax Examples

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/字段元数据FieldItem与ShowIn.md

Demonstrates the three supported syntaxes for configuring ShowIn options: named lists, pipe-separated segments, and character masks.

```csharp
1. 具名列表（推荐）
   - `ShowIn="List,Search"`
   - `ShowIn="All,-Detail"`
2. 管道五段
   - `ShowIn="Y|Y|N||A"`
3. 五字符掩码
   - `ShowIn="10A?-"`
```

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

### Entity Model Definition Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode使用手册.md

An example of an entity model definition in XML format.

```xml
<?xml version="1.0" encoding="utf-8"?>
<EntityModel xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" 
             xs:schemaLocation="https://newlifex.com https://newlifex.com/Model202509.xsd" 
             xmlns="https://newlifex.com/Model202509.xsd">
  <Option>
    <Namespace>Order.Data</Namespace>
    <ConnName>Order</ConnName>
    <Output>.\</Output>
    <ChineseFileName>True</ChineseFileName>
    <Nullable>True</Nullable>
    <HasIModel>True</HasIModel>
  </Option>
  <Tables>
    <Table Name="Order" Description="订单。电商订单主表">
      <Columns>
        <Column Name="Id" DataType="Int64" PrimaryKey="True" DataScale="time" Description="编号" />
        <Column Name="OrderNo" DataType="String" Master="True" Length="50" Nullable="False" Description="订单号" />
        <Column Name="UserId" DataType="Int32" Map="User@Id@Name" Description="用户" />
        <Column Name="Status" DataType="Int32" Type="Order.Data.OrderStatus" Description="状态" />
        <Column Name="TotalAmount" DataType="Decimal" Precision="18" Scale="2" Description="总金额" />
        <Column Name="Remark" DataType="String" Length="500" Description="备注" Category="扩展" />
        <Column Name="CreateUser" DataType="String" Description="创建者" Model="False" Category="扩展" />
        <Column Name="CreateTime" DataType="DateTime" Nullable="False" Description="创建时间" Category="扩展" />
        <Column Name="UpdateTime" DataType="DateTime" Description="更新时间" Model="False" Category="扩展" />
      </Columns>
      <Indexes>
        <Index Columns="OrderNo" Unique="True" />
        <Index Columns="UserId" />
        <Index Columns="Status,CreateTime" />
      </Indexes>
    </Table>
  </Tables>
</EntityModel>
```

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

### CRUD Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Readme.MD

Example of performing CRUD operations using the generated UserInfo entity.

```csharp
using XCode;

var user = new UserInfo { UserName="张三", Password="123456", Age=18 };
user.Insert();

var u2 = UserInfo.FindById(user.Id);
u2.Age = 19;
u2.Update();

var list = UserInfo.FindAll(UserInfo._.Age > 10 & UserInfo._.UserName == "张三");
UserInfo.FindById(user.Id)?.Delete();
```

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

### Typical Usage

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/单对象缓存SingleCache.md

Demonstrates how to read from the cache using the primary key and a slave key.

```csharp
// 主键读
var user = User.Meta.SingleCache[1001];

// 从键读（例如用户名）
var user2 = User.Meta.SingleCache.GetItemWithSlaveKey("admin");
```

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

### Automatic Module Upgrade Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/XCode/Code/EntityBuilder模块名称升级说明.md

Example of how to automatically upgrade XCode versions when calling EntityBuilder.BuildTables().

```csharp
// 自动检测 XCode 版本并执行升级
EntityBuilder.BuildTables(tables, option, log);
```

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

### TimeShardPolicy Configuration Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/时间分片策略与范围裁剪（TimeShardPolicy）.md

Example of configuring TimeShardPolicy with specific connection and table policies, and a daily step.

```csharp
Meta.ShardPolicy = new TimeShardPolicy(nameof(CreateTime), Meta.Factory)
{
    ConnPolicy = "{0}",
    TablePolicy = "{0}_{1:yyyyMM}",
    Step = TimeSpan.FromDays(1)
};
```

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

### Path Query Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/树形实体.md

Shows how to find a node by its path and how to retrieve the full path string of a node.

```csharp
// 按路径查找节点，路径格式：中国/广东/广州
var node = Area.FindByPath("中国/广东/广州");

// 获取完整路径字符串（默认分隔符 /）
var path = node.GetFullPath();        // 中国/广东/广州
var path2 = node.GetFullPath(false);  // 中国/广东（不含自身）
```

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

### EntitySplit Usage Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/分库分表临时切换（EntitySplit）.md

An example demonstrating how to use EntitySplit to temporarily switch the database and table for a specific operation.

```csharp
factory.Split("Db_202603", "Log_202603", () =>
{
    return Log.FindCount();
});
```

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

### 辅助功能 - 临时改变 ShowSQL

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据库会话接口（IDbSession）.md

使用 using 语句临时改变 ShowSQL 选项，并在离开作用域时自动还原。

```csharp
// 临时改变 ShowSQL 并自动还原
using var _ = session.SetShowSql(true);
```

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

### External Version Detection Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/XCode/Code/EntityBuilder模块名称升级说明.md

Example of detecting XCode version using external tools like xcodetool.

```csharp
// 检测当前目录的 XCode 版本
var version = EntityBuilder.DetectXCodeVersion(Environment.CurrentDirectory);
if (EntityBuilder.NeedUpgradeModuleNames(version))
{
    Console.WriteLine($"当前 XCode 版本 {version} 需要升级模块名称");
}
```

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

### Usage Example in MySQL Driver

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/驱动自动加载与下载（DriverLoader）.md

Demonstrates how the `CreateFactory` method in a database driver (specifically MySQL) uses `DriverLoader.Load` to obtain the necessary `DbProviderFactory`.

```csharp
// MySQL driver example
protected override DbProviderFactory? CreateFactory()
{
    return DriverLoader.Load(
        "MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data",
        "MySql",
        "MySql.Data.dll",
        "MySql.Data",
        null,
        new Version("8.0")
    ) as DbProviderFactory;
}
```

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

### Quick Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/连接字符串构造与脱敏处理（ConnectionStringBuilder）.md

Demonstrates basic usage of ConnectionStringBuilder for modifying database, adding pooling, and handling password removal.

```csharp
var b = new ConnectionStringBuilder("Server=127.0.0.1;Database=Test;User=sa;Password=123456");

b["Database"] = "Prod";
b.TryAdd("Pooling", "true");

if (b.TryGetAndRemove("Password", out var pwd))
{
    // 可在这里做脱敏日志或密钥托管
}

var conn = b.ConnectionString;
```

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

### Query Combination Example - This Month + Status Filter

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/字段时间区间扩展（FieldExtension）.md

Example demonstrating how to combine a time period filter (ThisMonth) with a status filter.

```csharp
// This month + status filter
var list = Order.FindAll(
    _.CreateTime.ThisMonth() & _.Status == 1,
    _.Id.Desc(),
    null,
    0, 20
);
```

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

### Query Combination Example - Custom Range + User Filter

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/字段时间区间扩展（FieldExtension）.md

Example showing how to combine a custom date range with a user ID filter.

```csharp
var exp = _.CreateTime.Between(startDate, endDate) & _.UserId == userId;
```

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

### 自动填充用户信息

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/业务审计日志（LogProvider）.md

CreateLog 内部会调用，无需手动传入用户，Cube 环境下自动来自当前请求上下文。

```csharp
var user = ManageProvider.Provider?.Current;
if (user != null)
{
    log.CreateUserID = user.ID;
    log.UserName     = user.ToString();
}
log.CreateIP = ManageProvider.UserHost;
```

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

### 设置数据权限上下文

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据权限.md

在请求开始时设置当前用户的数据权限上下文。

```csharp
// ASP.NET Core 中间件示例
public class DataScopeMiddleware
{
    public async Task InvokeAsync(HttpContext context, IManageProvider provider)
    {
        var user = provider.Current as IUser;
        if (user != null)
        {
            // 从用户创建数据权限上下文
            DataScopeContext.Current = DataScopeContext.Create(user);
        }
        
        try
        {
            await _next(context);
        }
        finally
        {
            DataScopeContext.Current = null;
        }
    }
}
```

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

### Enable 开关

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/业务审计日志（LogProvider）.md

全局禁用日志记录，适用于压测/迁移场景。

```csharp
// 全局禁用（如压测/迁移场景）
LogProvider.Provider.Enable = false;
```

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

### BindIndexAttribute Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体绑定特性（Attributes）.md

标注在实体类上（可多次），声明数据表索引。

```csharp
[BindIndex("IU_User_Name", true, "Name")]
[BindIndex("IX_User_RoleId", false, "RoleId")]
public partial class User : Entity<User> { }
```

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

### 创建项目

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode使用手册.md

创建数据类库项目、Web 管理后台和控制台应用的命令。

```powershell
# 创建数据类库项目
dotnet new xcode -n MyApp.Data

# 创建 Web 管理后台
dotnet new cube -n MyAppWeb

# 创建控制台应用
dotnet new nconsole -n MyAppConsole
```

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

### 基本用法

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据初始化（InitData）.md

在业务类（xxx.Biz.cs）中重写 InitData() 方法，用于在实体第一次初始化时插入默认数据。示例展示了如何插入角色信息，并包含了一个检查以防止重复写入。

```csharp
public partial class Role : Entity<Role>
{
    protected override void InitData()
    {
        if (Meta.Count > 0) return;  // 已有数据则不重复写入

        var roles = new[]
        {
            new Role { Name = "管理员", Enable = true, IsSystem = true, Sort = 1 },
            new Role { Name = "普通用户", Enable = true, Sort = 2 },
        };
        roles.Insert();  // 批量插入
    }
}
```

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

### BindColumnAttribute Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体绑定特性（Attributes）.md

标注在实体属性上，声明该属性对应的数据列。

```csharp
[BindColumn("UserName", "用户名。登录账号", "", Master = true)]
public String? UserName { get; set; }

[BindColumn("LastLoginIP", "最后登录IP", "varchar(50)", ShowIn = "-EditForm,-AddForm")]
public String? LastLoginIP { get; set; }
```

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

### BindTableAttribute Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体绑定特性（Attributes）.md

标注在实体类上，声明该类对应的数据表。

```csharp
[BindTable("User", Description = "用户。系统管理用户", ConnName = "Sys", DbType = DatabaseType.None)]
public partial class User : Entity<User> { }
```

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

### 菜单级数据权限设置示例

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据权限.md

展示了如何通过 DataScopeContext.Create 或 DataScopeContext.Current.SetMenu 来设置当前菜单的数据权限。

```csharp
// 设置当前菜单
var ctx = DataScopeContext.Create(user, menuId: 100);

// 或者动态设置
DataScopeContext.Current?.SetMenu(menuId);
```

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

### MapAttribute Example

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体绑定特性（Attributes）.md

标注在外键属性上（如 RoleId），声明关联实体的映射关系，用于自动提供下拉数据源与扩展属性。

```csharp
[Map(nameof(RoleId), typeof(Role), "Id")]
public Int32 RoleId { get; set; }
```

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

### Creating a DataScopeContext

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/数据权限.md

Recommended way to create a DataScopeContext from a user object.

```csharp
// 从用户创建上下文
var ctx = DataScopeContext.Create(user);

// 也可以指定菜单，实现菜单级数据权限
var ctx = DataScopeContext.Create(user, menuId: 100);
```

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

### using 方式事务处理

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode使用手册.md

演示推荐的 using 方式进行事务处理。

```csharp
using var tran = User.Meta.CreateTrans();

var user = new User { Name = "test" };
user.Insert();

var log = new Log { Action = "新增用户" };
log.Insert();

tran.Commit();  // 不调用则自动回滚
```

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

### Registering TimeInterceptor

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体拦截器（IEntityInterceptor）.md

Example of registering the TimeInterceptor in the static constructor of an entity.

```csharp
static MyEntity()
{
    // 推荐新写法
    Meta.Modules.Add<TimeInterceptor>();

    // 旧写法（仍可用，内部等价）
    Meta.Modules.Add<TimeModule>();
}
```

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

### Clear Cache

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/实体扩展字典（EntityExtend）.md

Example of clearing all extended property caches for an entity.

```csharp
entity.Extends.Clear();    // 清空该实体的全部扩展属性缓存
```

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

### 配置数据库连接

Source: https://github.com/newlifex/newlife.xcode/blob/master/Doc/XCode使用手册.md

在 appsettings.json 文件中配置数据库连接的 JSON 示例。

```json
{
  "ConnectionStrings": {
    "Default": "Server=.;Database=MyApp;Uid=sa;Pwd=xxx"
  }
}
```