EFCore PostgreSQL在.NET9生成迁移文件错误.md

如果在将.net 9的项目生成的迁移文件应用到数据库的时候出现

System.InvalidOperationException: An error was generated for warning 'Microsoft.EntityFrameworkCore.Migrations.PendingModelChangesWarning': The model for context 'SiteDbContext' has pending changes. Add a new migration before updating the database. This exception can be suppressed or logged by passing event ID 'RelationalEventId.PendingModelChangesWarning' to the 'ConfigureWarnings' method in 'DbContext.OnConfiguring' or 'AddDbContext'.
   at Microsoft.EntityFrameworkCore.Diagnostics.EventDefinition`1.Log[TLoggerCategory](IDiagnosticsLogger`1 logger, TParam arg)
   at Microsoft.EntityFrameworkCore.Diagnostics.RelationalLoggerExtensions.PendingModelChangesWarning(IDiagnosticsLogger`1 diagnostics, Type contextType)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Migrations.Internal.NpgsqlMigrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String connectionString, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String connectionString, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
An error was generated for warning 'Microsoft.EntityFrameworkCore.Migrations.PendingModelChangesWarning': The model for context 'SiteDbContext' has pending changes. Add a new migration before updating the database. This exception can be suppressed or logged by passing event ID 'RelationalEventId.PendingModelChangesWarning' to the 'ConfigureWarnings' method in 'DbContext.OnConfiguring' or 'AddDbContext'.

中文翻译错误就是：

警告为“Microsoft.EntityFrameworkCore.Migrations.PendingModelChangesWarning”：'SiteDbContext'上下文存在待处理的更改。在更新数据库之前请添加一个新的迁移。可以通过将事件ID 'RelationalEventId.PendingModelChangesWarning' 传递到'DbContext.OnConfiguring'或'AddDbContext'中的'ConfigureWarnings'方法来抑制或记录此异常。

当出现这个错误的时候其实我们可以通过配置日志进行忽略，下面是代码：

public class ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : IdentityDbContext<ApplicationUser>(options)
{
    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        builder.Entity<ApplicationRole>().HasData(new ApplicationRole { Name = "User", NormalizedName = "USER", Id = Guid.NewGuid().ToString(), ConcurrencyStamp = Guid.NewGuid().ToString() });
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);

        optionsBuilder.ConfigureWarnings(warnings => warnings.Ignore(RelationalEventId.PendingModelChangesWarning));
    }
}

主要是 optionsBuilder.ConfigureWarnings(warnings => warnings.Ignore(RelationalEventId.PendingModelChangesWarning));忽略掉这个错误，因为这个错误其实只是一个警告，但是新版本直接会报错。