【发布时间】：2021-05-16 06:24:19
【问题描述】：
我正在尝试创建一个项目。这就是我从this link 下载启动模板的原因。然后我尝试使用 asp.net core 进行配置。我将连接字符串设置为"Default": "User ID=postgres;Password=**********;Host=localhost;Port=5432;Database=LibraryManagementDb;Pooling=true;"。然后在 LibraryManagementDbContextConfigurer 类中将UseSqlServer 更改为UseNpgsql。
`
public static void
Configure(DbContextOptionsBuilder<LibraryManagementDbContext>
builder, string connectionString)
{
builder.UseNpgsql(connectionString);
}
public static void
Configure(DbContextOptionsBuilder<LibraryManagementDbContext>
builder, DbConnection connection)
{
builder.UseNpgsql(connection);
}
`
并将以下代码添加到 DbContext 类中
`
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<ApplicationLanguageText>()
.Property(p => p.Value)
.HasMaxLength(100); // any integer that is smaller than 10485760
}
`
并从 Migration 文件夹中删除所有迁移类，并在包管理器控制台中运行 add-migration Initial_Migration 命令
但我得到 异常已被调用目标抛出。错误
这是整个例外
`
PM> add-migration Initial_Migration
Build started...
Build succeeded.
System.Reflection.TargetInvocationException: Exception has been
thrown by the target of an invocation.
---> System.TypeLoadException: Method 'get_Info' in type
'Microsoft.EntityFrameworkCore.Infrastructure.
Internal.NpgsqlOptionsExt
ension' from assembly 'Npgsql.EntityFrameworkCore.PostgreSQL,
Version=2.1.0.0, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7'
does not have an implementation.
at Microsoft.EntityFrameworkCore
.NpgsqlDbContextOptionsExtensions.UseNpgsql[TContext]
at LibraryManagement.EntityFrameworkCore
.LibraryManagementDbContextConfigurer
.Configure(DbContextOptionsBuilder`1 builder, String
connectionString) in D:\6.0.0\aspnet-
core\src\LibraryManagement.EntityFrameworkCore
\EntityFrameworkCore\LibraryManagementDbContextConfigurer.cs:line
10
at LibraryManagement.EntityFrameworkCore
.LibraryManagementDbContextFactory.CreateDbContext(String[] args)
in D:\6.0.0\aspnet-core\src\LibraryManagement.EntityFrameworkCore
\EntityFrameworkCore\LibraryManagementDbContextFactory.cs:line 17
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
arguments, Signature sig, Boolean constructor, Boolean
wrapExceptions)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj,
BindingFlags invokeAttr, Binder binder, Object[] parameters,
CultureInfo culture)
at System.Reflection.MethodBase.Invoke(Object obj, Object[]
parameters)
at Microsoft.EntityFrameworkCore.Design
.Internal.DbContextOperations.CreateContextFromFactory(Type
factory,
Type contextType)
at
Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.
<>c__DisplayClass16_0.<FindContextFactory>b__1()
at Microsoft.EntityFrameworkCore.Design.Internal
.DbContextOperations.CreateContext(Func`1 factory)
at Microsoft.EntityFrameworkCore.Design.Internal
.DbContextOperations.CreateContext(String contextType)
at Microsoft.EntityFrameworkCore.Design.Internal
.MigrationsOperations.AddMigration(String name, String outputDir,
String contextType, String namespace)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor
.AddMigrationImpl(String name, String outputDir, String
contextType,
String namespace)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor
.AddMigration.<>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)
Exception has been thrown by the target of an invocation.
`
我该如何解决这个问题？？？请帮忙...
【问题讨论】：
-
你的 'EntityFramework' 和 'Npgsql.EntityFrameworkCore.PostgreSQL' 的版本是什么？
-
'Npgsql.EntityFrameworkCore.PostgreSQL' 版本是 5.0.2（最新），但不知道 'EntityFramework' 的版本。但我在我的电脑上安装了.net core，版本是 5.0.103。不确定这是“EntityFramework”版本吗？或者如何检查“EntityFramework”版本？
-
Entity Framework 6 和 Entity Framework Core 都安装好了
标签： asp.net postgresql asp.net-core entity-framework-core aspnetboilerplate