Question

我正在尝试将现有的PostgreSQL数据库转换为具有Entity Framework Core 2.0.1的实体，但是我在脚手架时遇到错误。数据库是通过运行以下脚本创建的： https://stackblitz.com/edit/angular-xfrezb

然后我在VS2017中运行以下命令：

System.ArgumentException: The collection argument 'propertyNames' must contain at least one element.
   at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty[T](IReadOnlyList`1 value, String parameterName)
   at Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder.HasIndex(String[] propertyNames)
   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.CreateFromDatabaseModel(DatabaseModel databaseModel, 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)
The collection argument 'propertyNames' must contain at least one element.

该操作运行良好一点（有一些警告，见下文），但它失败并显示以下错误消息：

Sequence with datatype integer which isn't the expected bigint.
Sequence with datatype integer which isn't the expected bigint.
Sequence with datatype integer which isn't the expected bigint.
The column 'tiger.street_type_lookup.is_hw' would normally be mapped to a non-nullable bool property, but it has a default constraint. Such a column is mapped to a nullable bool property to allow a difference between setting the property to false and invoking the default constraint. See https://go.microsoft.com/fwlink/?linkid=851278 for details.

有人知道这里的问题是什么吗？

我也收到以下两种类型的警告。这是次要的，但我也非常感谢帮助理解和解决它们。

F:\Downloads\Downloads\500 Comics CCC English\Jack, Byrd - Art #01.cbr

Answer 1

您是否有任何带表达式的索引作为参数？类似的东西：

UserControl

表达式可以在pg_indexes表中插入为已损坏。

您可以通过

查看

DataContext

祝你好运！

Answer 2

关于序列警告，序列返回类型和主键列Id之间可能不匹配。您可以使用BIGSERIAL，即BIGINT +自动增量，这样就可以避免序列手动输入。作为foreing键列类型使用BIGINT。

关于is_hw列，它有一个可能导致可以为空的值的约束，另一方面，同一列可能被设置为NOT NULL。

这会帮助你https://github.com/npgsql/npgsql/issues/892吗？

Answer 3

我不确定这篇文章是否仍然有效;但是，在使用Entity Framework时我遇到了同样的错误，事实证明我的sql帐户需要对数据库的额外访问权限。我给它db.owner访问权限，因为这只是一个本地测试项目，它工作。

Answer 4

此错误与 @tim-potter 回答说这是索引的错误用法完全一样，导致运行时为 System.ArgumentException: The collection argument 'propertyNames' must contain at least one element.

要解决这个问题：在模型类中，找到这个属性 [Index(Name = "PropertyName", IsUnique = true/false)]，当你找到那个属性时，确保字符串 Name 而不是：

Name = "PropertyName" 使用 nameof(PropertyName)

我认为索引属性中的 Name 属性不起作用的原因是实体框架中的错误。

EFCore数据库第一个脚手架错误

4 个答案: