實體框架6代碼優先功能映射

c# ef-code-first entity-framework entity-framework-6 sql-function

我想將Entity Framework 6集成到我們的系統中,但是有問題。

  1. 我想使用Code First。出於其他原因,我不想使用Database First * .edmx文件。
  2. 我使用屬性映射[表],[列],這很好用
  3. 數據庫有許多用戶定義的函數,我需要在Linq To Entities查詢中使用它們。

問題是:

我不能通過像[Table],[Column]這樣的屬性來映射函數。只有1個屬性可用[DbFunction],它需要* .edmx文件。

我可以在* .edmx文件中映射函數,但這意味著我不能使用實體的屬性映射:[Table],[Column]。必須在* .edmx或屬性中填充映射。

我嘗試通過以下代碼創建DbModel並添加函數:

public static class Functions
{
    [DbFunction("CodeFirstNamespace", "TestEntity")]
    public static string TestEntity()
    {
        throw new NotSupportedException();
    }
}


public class MyContext : DbContext, IDataAccess
{
    protected MyContext (string connectionString)
        : base(connectionString, CreateModel())
    {
    }

    private static DbCompiledModel CreateModel()
    {
        var dbModelBuilder = new DbModelBuilder(DbModelBuilderVersion.Latest);
        dbModelBuilder.Entity<Warehouse>();
        var dbModel = dbModelBuilder.Build(new DbProviderInfo("System.Data.SqlClient", "2008"));

        var edmType = PrimitiveType.GetEdmPrimitiveType(PrimitiveTypeKind.String);
        var payload =
            new EdmFunctionPayload
            {
                Schema = "dbo",
                ParameterTypeSemantics = ParameterTypeSemantics.AllowImplicitConversion,
                IsComposable = true,
                IsNiladic = false,
                IsBuiltIn = false,
                IsAggregate = false,
                IsFromProviderManifest = true,
                StoreFunctionName = "TestEntity",
                ReturnParameters =
                    new[]
                    {
                        FunctionParameter.Create("ReturnType", edmType, ParameterMode.ReturnValue)
                    }
            };

        var function = EdmFunction.Create("TestEntity", "CodeFirst", DataSpace.CSpace, payload, null);
        dbModel.DatabaseMapping.Model.AddItem(function);
        var compiledModel = dbModel.Compile();       // Error happens here
        return compiledModel;
    }
}

但有例外:

在模型生成期間檢測到一個或多個驗證錯誤:

public static class Functions
{
    [DbFunction("CodeFirstNamespace", "TestEntity")]
    public static string TestEntity()
    {
        throw new NotSupportedException();
    }
}


public class MyContext : DbContext, IDataAccess
{
    protected MyContext (string connectionString)
        : base(connectionString, CreateModel())
    {
    }

    private static DbCompiledModel CreateModel()
    {
        var dbModelBuilder = new DbModelBuilder(DbModelBuilderVersion.Latest);
        dbModelBuilder.Entity<Warehouse>();
        var dbModel = dbModelBuilder.Build(new DbProviderInfo("System.Data.SqlClient", "2008"));

        var edmType = PrimitiveType.GetEdmPrimitiveType(PrimitiveTypeKind.String);
        var payload =
            new EdmFunctionPayload
            {
                Schema = "dbo",
                ParameterTypeSemantics = ParameterTypeSemantics.AllowImplicitConversion,
                IsComposable = true,
                IsNiladic = false,
                IsBuiltIn = false,
                IsAggregate = false,
                IsFromProviderManifest = true,
                StoreFunctionName = "TestEntity",
                ReturnParameters =
                    new[]
                    {
                        FunctionParameter.Create("ReturnType", edmType, ParameterMode.ReturnValue)
                    }
            };

        var function = EdmFunction.Create("TestEntity", "CodeFirst", DataSpace.CSpace, payload, null);
        dbModel.DatabaseMapping.Model.AddItem(function);
        var compiledModel = dbModel.Compile();       // Error happens here
        return compiledModel;
    }
}

問題在於“edmType”變量。我無法為函數創建正確的ReturnType。任何人都可以建議我如何將功能添加到模型中?添加功能的界面是暴露的,所以它應該能夠做到,但是在這種情況下web中沒有信息。可能有人知道Entity Framework團隊何時會為Line To Sql這樣的函數實現屬性映射。

EF版本:6.0.0-beta1-20521

謝謝!


是的,這適合我。但僅適用於標量函數。我也需要map函數,它返回IQueryable:

public static class Functions
{
    [DbFunction("CodeFirstNamespace", "TestEntity")]
    public static string TestEntity()
    {
        throw new NotSupportedException();
    }
}


public class MyContext : DbContext, IDataAccess
{
    protected MyContext (string connectionString)
        : base(connectionString, CreateModel())
    {
    }

    private static DbCompiledModel CreateModel()
    {
        var dbModelBuilder = new DbModelBuilder(DbModelBuilderVersion.Latest);
        dbModelBuilder.Entity<Warehouse>();
        var dbModel = dbModelBuilder.Build(new DbProviderInfo("System.Data.SqlClient", "2008"));

        var edmType = PrimitiveType.GetEdmPrimitiveType(PrimitiveTypeKind.String);
        var payload =
            new EdmFunctionPayload
            {
                Schema = "dbo",
                ParameterTypeSemantics = ParameterTypeSemantics.AllowImplicitConversion,
                IsComposable = true,
                IsNiladic = false,
                IsBuiltIn = false,
                IsAggregate = false,
                IsFromProviderManifest = true,
                StoreFunctionName = "TestEntity",
                ReturnParameters =
                    new[]
                    {
                        FunctionParameter.Create("ReturnType", edmType, ParameterMode.ReturnValue)
                    }
            };

        var function = EdmFunction.Create("TestEntity", "CodeFirst", DataSpace.CSpace, payload, null);
        dbModel.DatabaseMapping.Model.AddItem(function);
        var compiledModel = dbModel.Compile();       // Error happens here
        return compiledModel;
    }
}

其中T是EntityType或RowType或任何類型。我完全不能這樣做(EF版本是6.0.2-21211)。我認為這應該以這種方式工作:

public static class Functions
{
    [DbFunction("CodeFirstNamespace", "TestEntity")]
    public static string TestEntity()
    {
        throw new NotSupportedException();
    }
}


public class MyContext : DbContext, IDataAccess
{
    protected MyContext (string connectionString)
        : base(connectionString, CreateModel())
    {
    }

    private static DbCompiledModel CreateModel()
    {
        var dbModelBuilder = new DbModelBuilder(DbModelBuilderVersion.Latest);
        dbModelBuilder.Entity<Warehouse>();
        var dbModel = dbModelBuilder.Build(new DbProviderInfo("System.Data.SqlClient", "2008"));

        var edmType = PrimitiveType.GetEdmPrimitiveType(PrimitiveTypeKind.String);
        var payload =
            new EdmFunctionPayload
            {
                Schema = "dbo",
                ParameterTypeSemantics = ParameterTypeSemantics.AllowImplicitConversion,
                IsComposable = true,
                IsNiladic = false,
                IsBuiltIn = false,
                IsAggregate = false,
                IsFromProviderManifest = true,
                StoreFunctionName = "TestEntity",
                ReturnParameters =
                    new[]
                    {
                        FunctionParameter.Create("ReturnType", edmType, ParameterMode.ReturnValue)
                    }
            };

        var function = EdmFunction.Create("TestEntity", "CodeFirst", DataSpace.CSpace, payload, null);
        dbModel.DatabaseMapping.Model.AddItem(function);
        var compiledModel = dbModel.Compile();       // Error happens here
        return compiledModel;
    }
}

但仍然沒有運氣:

public static class Functions
{
    [DbFunction("CodeFirstNamespace", "TestEntity")]
    public static string TestEntity()
    {
        throw new NotSupportedException();
    }
}


public class MyContext : DbContext, IDataAccess
{
    protected MyContext (string connectionString)
        : base(connectionString, CreateModel())
    {
    }

    private static DbCompiledModel CreateModel()
    {
        var dbModelBuilder = new DbModelBuilder(DbModelBuilderVersion.Latest);
        dbModelBuilder.Entity<Warehouse>();
        var dbModel = dbModelBuilder.Build(new DbProviderInfo("System.Data.SqlClient", "2008"));

        var edmType = PrimitiveType.GetEdmPrimitiveType(PrimitiveTypeKind.String);
        var payload =
            new EdmFunctionPayload
            {
                Schema = "dbo",
                ParameterTypeSemantics = ParameterTypeSemantics.AllowImplicitConversion,
                IsComposable = true,
                IsNiladic = false,
                IsBuiltIn = false,
                IsAggregate = false,
                IsFromProviderManifest = true,
                StoreFunctionName = "TestEntity",
                ReturnParameters =
                    new[]
                    {
                        FunctionParameter.Create("ReturnType", edmType, ParameterMode.ReturnValue)
                    }
            };

        var function = EdmFunction.Create("TestEntity", "CodeFirst", DataSpace.CSpace, payload, null);
        dbModel.DatabaseMapping.Model.AddItem(function);
        var compiledModel = dbModel.Compile();       // Error happens here
        return compiledModel;
    }
}

有可能嗎?可能步驟不對?可能會在EF 6.1上添加支持。任何信息都非常有用。

謝謝!

熱門答案

尚未嘗試過,但Entity Framework 6.1包含公共映射API 。 Moozzyk使用這一新功能為EntityFramework CodeFirst實現了Store Functions

這是代碼的樣子:

public class MyContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Add(new FunctionsConvention<MyContext>("dbo"));
    }

    [DbFunction("MyContext", "CustomersByZipCode")]
    public IQueryable<Customer> CustomersByZipCode(string zipCode)
    {
        var zipCodeParameter = zipCode != null ?
            new ObjectParameter("ZipCode", zipCode) :
            new ObjectParameter("ZipCode", typeof(string));

        return ((IObjectContextAdapter)this).ObjectContext
            .CreateQuery<Customer>(
                string.Format("[{0}].{1}", GetType().Name, 
                    "[CustomersByZipCode](@ZipCode)"), zipCodeParameter);
    }

    public ObjectResult<Customer> GetCustomersByName(string name)
    {
        var nameParameter = name != null ?
            new ObjectParameter("Name", name) :
            new ObjectParameter("Name", typeof(string));

        return ((IObjectContextAdapter)this).ObjectContext.
            ExecuteFunction("GetCustomersByName", nameParameter);
    }
}



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不隸屬於 Stack Overflow
這個KB合法嗎? 是的,了解原因
許可下: CC-BY-SA with attribution
不隸屬於 Stack Overflow
這個KB合法嗎? 是的,了解原因