Question

当我运行命令Scaffold-DbContext "Server=localhost;Database=MyDatabase;Integrated Security=true" Microsoft.EntityFrameworkCore.SqlServer

时

我收到错误：

System.ArgumentNullException: Value cannot be null.
Parameter name: proposedIdentifier
   at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty(String value, String parameterName)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpUtilities.Uniquifier(String proposedIdentifier, ICollection`1 existingIdentifiers)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpUtilities.GenerateCSharpIdentifier(String identifier, ICollection`1 existingIdentifiers, Func`2 singularizePluralizer, Func`3 uniquifier)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpUtilities.GenerateCSharpIdentifier(String identifier, ICollection`1 existingIdentifiers, Func`2 singularizePluralizer)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpNamer`1.GetName(T item)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpUniqueNamer`1.GetName(T item)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.GetEntityTypeName(DatabaseTable table)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.VisitTable(ModelBuilder modelBuilder, DatabaseTable table)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.VisitTables(ModelBuilder modelBuilder, ICollection`1 tables)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.VisitDatabaseModel(ModelBuilder modelBuilder, DatabaseModel databaseModel)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.CreateFromDatabaseModel(DatabaseModel databaseModel, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.Create(String connectionString, IEnumerable`1 tables, IEnumerable`1 schemas, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ModelScaffolder.Generate(String connectionString, IEnumerable`1 tables, IEnumerable`1 schemas, String projectPath, String outputPath, String rootNamespace, String contextName, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String dbContextClassName, IEnumerable`1 schemas, IEnumerable`1 tables, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String dbContextClassName, IEnumerable`1 schemaFilters, IEnumerable`1 tableFilters, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_1.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Value cannot be null.
Parameter name: proposedIdentifier.

在我的启动项目中，我有：

public class CustomPluralizerDesignTimeServices : IDesignTimeServices
{
    public void ConfigureDesignTimeServices(IServiceCollection services)
    {
        services.AddSingleton<IPluralizer, HumanizerToIPluralizerAdapter>();
    }
}

public class HumanizerToIPluralizerAdapter : IPluralizer
{
    public string Pluralize(string name) => name.Pluralize();

    public string Singularize(string name) => name.Singularize();
}

当我删除此代码时，脚手架工作。

依赖关系：

DataAccess项目（.NET标准2.0）
- Microsoft.EntityFrameworkCore.SqlServer 2.0
- Microsoft.EntityFrameworkCore.Tools
- Microsoft.VisualStudio.Web.CodeGeneration.Design
启动项目（.NET CORE 2.0）
- Microsoft.AspNetCore.All

Answer 1

看起来像IPluralizer实施中的错误。确保它没有为某些值返回null或空字符串。

Scaffold-DbContext在尝试复数时返回System.ArgumentNullException：EFCore 2.0中的参数名称：proposedIdentifier

1 个答案: