Pomelo 实体框架核心基架在 MySQL DB "annotation cannot be added because an annotation with the same name alrea

Question

当我尝试使用构建现有MySQL数据库时

脚手架DbContext"；server=服务器；user=用户；密码=pw；database=db"柚子EntityFrameworkCore。MySql"-OutputDir EF-f

我得到以下错误：

System.InvalidOperationException: The annotation 'MySql:IndexPrefixLength' cannot be added because an annotation with the same name already exists**.
at Microsoft.EntityFrameworkCore.Infrastructure.Annotatable.AddAnnotation(String name, Annotation annotation)
at Microsoft.EntityFrameworkCore.Infrastructure.Annotatable.AddAnnotation(String name, Object value)
at Microsoft.EntityFrameworkCore.Infrastructure.Annotatable.Microsoft.EntityFrameworkCore.Metadata.IMutableAnnotatable.AddAnnotation(String name, Object value)
at Microsoft.EntityFrameworkCore.MutableAnnotatableExtensions.AddAnnotations(IMutableAnnotatable annotatable, IEnumerable`1 annotations)
at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.VisitIndex(EntityTypeBuilder builder, DatabaseIndex index)
at Microsoft.EntityFrameworkCore.Scaffolding.Internal.RelationalScaffoldingModelFactory.VisitIndexes(EntityTypeBuilder builder, ICollection`1 indexes)
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.Create(DatabaseModel databaseModel, Boolean useDatabaseNames)
at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ReverseEngineerScaffolder.ScaffoldModel(String connectionString, DatabaseModelFactoryOptions databaseOptions, ModelReverseEngineerOptions modelOptions, ModelCodeGenerationOptions codeOptions)
at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String outputContextDir, 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 outputDbContextDir, String dbContextClassName, IEnumerable`1 schemaFilters, IEnumerable`1 tableFilters, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_0.<.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)
The annotation 'MySql:IndexPrefixLength' cannot be added because an annotation with the same name already exists.*

我已经成功地在同一个项目中使用微软软件包为同一个数据库搭建了脚手架，没有任何问题。

Answer 1

Pomelo团队已确认该问题为错误。如果一列上有多个索引，并且这两个索引都使用索引前缀，则会发生此异常。修复程序将很快发布：

https://github.com/PomeloFoundation/Pomelo.EntityFrameworkCore.MySql/issues/1189