EFCore的Index属性恢复 （带有模型构建的扩展 ）-C#-下载

# IndexColumnAttribute for EntityFramework Core [](https://www.nuget.org/packages/Toolbelt.EntityFrameworkCore.IndexAttribute/) [](https://github.com/jsakamoto/EntityFrameworkCore.IndexAttribute/actions/workflows/unit-tests.yml) ## What's this? The `[IndexColumn]` attribute that is the revival of `[Index]` attribute for EF Core. (with extension for model building.) ### Attention EF Core also includes the `[Index]` attribute officially, after ver.5.0. However, I'm going to continue improving and maintaining these libraries, because these libraries still have advantages as below. - You can still create indexes by data annotations even if you have to use **a lower version of EF Core**. - You can create indexes with **"included columns"** for SQL Server. - You can create a **clustered index** (This means you can also create a non-clustered primary key index). ## How to use? 1. Add [`Toolbelt.EntityFrameworkCore.IndexAttribute`](https://www.nuget.org/packages/Toolbelt.EntityFrameworkCore.IndexAttribute/) package to your project. ```shell > dotnet add package Toolbelt.EntityFrameworkCore.IndexAttribute ``` ### Supported Versions The version of EF Core | Version of this package -----------------------|------------------------- v.7.0 | **v.5.0.1 (Recommended)**, v.5.0, v.3.2, v.3.1 v.6.0 | **v.5.0.1 (Recommended)**, v.5.0, v.3.2, v.3.1 v.5.0 | **v.5.0.1 (Recommended)**, v.5.0, v.3.2, v.3.1 v.3.1 | **v.5.0.1 (Recommended)**, v.5.0, v.3.2, v.3.1 v.3.0 | **v.5.0.1 (Recommended)**, v.5.0, v.3.2, v.3.1, v.3.0 v.2.0, 2.1, 2.2 | v.2.0.x If you want to use `IsClustered=true` and/or `Includes` index features on a SQL Server, you have to add [`Toolbelt.EntityFrameworkCore.IndexAttribute.SqlServer`](https://www.nuget.org/packages/Toolbelt.EntityFrameworkCore.IndexAttribute.SqlServer/) package to your project, instead. ```shell > dotnet add package Toolbelt.EntityFrameworkCore.IndexAttribute.SqlServer ``` 2. Annotate your model with `[IndexColumn]` attribute that lives in `Toolbelt.ComponentModel.DataAnnotations.Schema.V5` namespace. _**Notice**_ - The attribute name is **`[IndexColumn]`**, is not `[Index]` (the attribute name `[Index]` is used by EFocre v.5.0). ```csharp using Toolbelt.ComponentModel.DataAnnotations.Schema.V5; public class Person { public int Id { get; set; } [IndexColumn] // <- Here! public string Name { get; set; } } ``` 3. **[Important]** Override `OnModelCreating()` method of your DbContext class, and call `BuildIndexesFromAnnotations()` extension method which lives in `Toolbelt.ComponentModel.DataAnnotations` namespace. ```csharp using Microsoft.EntityFrameworkCore; using Toolbelt.ComponentModel.DataAnnotations; public class MyDbContext : DbContext { ... // Override "OnModelCreating", ... protected override void OnModelCreatin(ModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); // .. and invoke"BuildIndexesFromAnnotations"! modelBuilder.BuildIndexesFromAnnotations(); } } ``` If you use SQL Server and `IsClustered=true` and/or `Includes = new[]{"Foo", "Bar"}` features, you need to call `BuildIndexesFromAnnotationsForSqlServer()` extension method instead of `BuildIndexesFromAnnotations()` extension method. ```csharp ... // Override "OnModelCreating", ... protected override void OnModelCreatingModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); // Invoke uildIndexesFromAnnotationsForSqlServer" // instead of "BuildIndexesFromAnnotations". modelBuilder.BuildIndexesFromAnnotationsForSqlServer; } ``` That's all! `BuildIndexesFromAnnotations()` (or, `BuildIndexesFromAnnotationsForSqlServer()`) extension method scans the DbContext with .NET Reflection technology, and detects `[IndexColumn]` attributes, then build models related to indexing. After doing that, the database which created by EF Core, contains indexes that are specified by `[IndexColumn]` attributes. ## Appendix A - Suppress "NotSupportedException" You will run into "NotSupportedException" when you call `BuildIndexesFromAnnotations()` with the model which is annotated with the `[IndexColumn]` attribute that's "IsClustered" property is true, or "Includes" property is not empty. If you have to call `BuildIndexesFromAnnotations()` in this case (for example, share the model for different Database products), you can suppress this behavior with configuration, like this. ```csharp ... protected override void OnModelCreating(ModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); // Suppress "NotSupportedException" for "IsClustered" and "Includes" feature. modelBuilder.BuildIndexesFromAnnotations(options => { options.SuppressNotSupportedException.IsClustered = true; options.SuppressNotSupportedException.Includes = true; }); } } ``` ## Appendix B - Notice for using "IsClustered=true" If you annotate the model with "IsClustered=true" index simply like this, ```csharp public class Employee { public int Id { get; set; } [IndexColumn(IsClustered = true)] public string EmployeeCode { get; set; } } ``` You will run into 'System.Data.SqlClient.SqlException' like this. ``` System.Data.SqlClient.SqlException : Cannot create more than one clustered index on table '(table name)'. Drop the existing clustered index '(index name)' before creating another. ``` In this case, you need to annotate a primary key property with `[PrimaryKey(IsClustered = false)]` attribute explicitly for suppress auto generated primary key to be clustered index. ```csharp public class Employee { [PrimaryKey(IsClustered = false)] // <- Add this line! public int Id { get; set; } [IndexColumn(IsClustered = true)] public string EmployeeCode { get; set; } } ``` ## Appendix C - If you want to use only "IndexAttribute" without any dependencies... If you want to use only "IndexColumnAttribute" class without any dependencies, you can use [Toolbelt.EntityFrameworkCore.IndexAttribute.Attribute](https://j.mp/3kfJgTm) NuGet package. ## Appendix D - Upgrade an existing project For more detail on this topic, please visit [this link.](https://j.mp/2HlmNFJ) ## Appendix E - If you run into a compile error CS0104... For more detail on this topic, please visit [this link.](https://j.mp/3476B3X) ## For More Detail... This library is designed to have the same syntax as EF 6.x `[Index]` annotation. Please visit document site of EF 6.x and `[Index]` attribute for EF 6.x. - [MSDN Document - Entity Framework Code First Data Annotations](https://j.mp/37hHBZI) - [MSDN Document - IndexAttribute class](https://j.mp/2HeIAzp) ## Limitations `[IndexColumn]` attribute with `IsClustered=true` can apply only not owned entity types. ## Release Notes - [Toolbelt.EntityFrameworkCore.IndexAttribute.Attibute](https://j.mp/3lSWUfw) - [Toolbelt.EntityFrameworkCore.IndexAttribute](https://j.mp/359Hg90) - [Toolbelt.EntityFrameworkCore.IndexAttribute.SqlServer](https://j.mp/3dBWDuu) ## License [MIT License](https://j.mp/3476mWB)