Question

我正在使用EF Core 2.0和Postgres 9.6。每当我插入数据时，我都会收到错误

PostgresException：23505：重复键值违反唯一约束＆＃34; PK_country＆＃34;

通过跟踪，看起来EF不会生成AutoInciment列

我的模特

public partial class Country
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int CountryId { get; set; }
        [Display(Name="Country Name")]
        public string CountryName { get; set; }
    }

我的控制器

if (ModelState.IsValid)
            {
                _context.Add(country);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }

异常

> PostgresException: 23505: duplicate key value violates unique
> constraint "PK_country"
> 
>     Npgsql.NpgsqlConnector+<DoReadMessage>d__148.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     System.Runtime.CompilerServices.TaskAwaiter.GetResult()
>     System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()
>     Npgsql.NpgsqlConnector+<ReadMessage>d__147.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     Npgsql.NpgsqlConnector+<ReadMessage>d__147.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     System.Runtime.CompilerServices.TaskAwaiter.GetResult()
>     System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()
>     Npgsql.NpgsqlDataReader+<NextResult>d__32.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     Npgsql.NpgsqlDataReader+<<NextResultAsync>b__31_0>d.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     Npgsql.NpgsqlCommand+<Execute>d__71.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     System.Runtime.CompilerServices.TaskAwaiter.GetResult()
>     System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()
>     Npgsql.NpgsqlCommand+<ExecuteDbDataReader>d__92.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     System.Runtime.CompilerServices.TaskAwaiter.GetResult()
>     System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()
>     Npgsql.NpgsqlCommand+<>c__DisplayClass90_0+<<ExecuteDbDataReaderAsync>b__0>d.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     System.Runtime.CompilerServices.TaskAwaiter.GetResult()
>     Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand+<ExecuteAsync>d__17.MoveNext()
>     System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
>     System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)
>     System.Runtime.CompilerServices.TaskAwaiter.GetResult()
>     Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch+<ExecuteAsync>d__32.MoveNext()

可能是什么问题？

Answer 1

我找到了解决方案。问题是我使用sql文件中的脚本为数据库播种。

$result = number_format(($number*900) /$boundary, $precision) . $postfix;

插入包含

context.Database.ExecuteSqlCommand(File.ReadAllText(baseDir + "\\data.sql"));

因此序列当前值未更新。当前值保持为1.所以当我插入应用程序时。 Autoincrment变为1因此 PostgresException：23505：重复键值违反唯一约束“PK_country”。

解决方案

ALTER TABLE country ENABLE TRIGGER ALL; 添加 SELECT pg_catalog.setval（pg_get_serial_sequence（'country'，'country_id'），MAX（country_id））FROM country;

现在它的应用程序已经成功运行。

希望帮助别人。

Answer 2

即使已经找到了此处的解决方案，该问题也没有指定您从某个.sql文件中加载数据。如果您已通过以下方式加载数据，则也会产生相同的错误：

_context.Add(new Country { CountryId = 0, CountryName = "MyCountry" });
_context.Add(new Country { CountryId = 1, CountryName = "MyCountry" });

原因是，（我不知道为什么）第一行将有CountryId = 1，第二行也有CountryId = 1。导致重复的键值。

这发生在：

Npgsql.EntityFrameworkCore.PostgreSQL 2.1.2
Microsoft.EntityFrameworkCore.Design 2.2.3

PostgresException：23505：重复键值违反了唯一约束＆＃34; PK_country＆＃34;

2 个答案: