使用 Postgresql 数据库更新 .NET7 项目中的数据库时收到“主机不能为空”错误

Question

我想请你帮忙。我有一个连接到 Postgresql 数据库系统的 .NET7 项目，该项目在 Windows 上的 Visual Studio 中完美运行，但当我在新 Macbook 上的任何 IDE（Visual Studio、Rider）中打开它时，会出现一些问题。当我点击命令“dotnet ef database update”时，我收到错误“主机不能为空”

Build started...
Build succeeded.
System.ArgumentException: Host can't be null
   at Npgsql.NpgsqlConnectionStringBuilder.PostProcessAndValidate()
   at Npgsql.NpgsqlConnection.SetupDataSource()
   at Npgsql.NpgsqlConnection.set_ConnectionString(String value)
   at Npgsql.NpgsqlConnection..ctor(String connectionString)
   at Npgsql.NpgsqlConnection.CloneWith(String connectionString)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlRelationalConnection.CloneWith(String connectionString)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlDatabaseCreator.Exists(Boolean async, CancellationToken cancellationToken)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlDatabaseCreator.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.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)
Host can't be null

我多次检查了我的连接字符串，它已正确附加，我的 dotnet ef 版本是 7.0.11，所有 NuGet 包也与该版本的 EF 兼容：

<Project Sdk="Microsoft.NET.Sdk">

  <ItemGroup>
      <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="7.0.15" />
      <PackageReference Include="Microsoft.EntityFrameworkCore" Version="7.0.11" />
      <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="7.0.11" />
      <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="7.0.11">
        <PrivateAssets>all</PrivateAssets>
        <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
      </PackageReference>
      <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
      <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="7.0.11" />
      <PackageReference Include="xunit" Version="2.5.1" />
      <PackageReference Include="xunit.runner.visualstudio" Version="2.5.1">
        <PrivateAssets>all</PrivateAssets>
        <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
      </PackageReference>
  </ItemGroup>

我还尝试使用具有相同版本的 EF 和包的数据库构建一个简单的项目，并且“dotnet ef 数据库更新”命令在那里完美运行。

这是我的 AppDbContext.cs：

    public class AppDbContext : DbContext
    {   
        //...some code

        protected readonly IConfiguration _configuration;

        public AppDbContext(DbContextOptions options, IConfiguration configuration) : base(options)
        {
            _configuration = configuration;
        }

        protected override void OnConfiguring(DbContextOptionsBuilder options)
        {
            options.UseNpgsql(_configuration.GetConnectionString("DefaultConnection"));
        } 

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());

            modelBuilder.HasSequence<int>
                ("BaggageTagsSequence").StartsAt(1).IncrementsBy(1).HasMax(999999).IsCyclic();
        }
    }

...我不知道是否有必要，但这也是Program.cs

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddDbContext<AppDbContext>(options =>
options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection"))
.LogTo(Console.WriteLine, LogLevel.Information));

builder.Services.AddSingleton<QueryExecutionService>();

builder.Services.AddControllers()
    .AddNewtonsoftJson()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.Preserve;
        options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
    });

builder.Services.AddApplicationServices(builder.Configuration);

var app = builder.Build();

// Configure the HTTP request pipeline.

app.UseMiddleware<ExceptionMiddleware>();

app.UseStatusCodePagesWithReExecute("/errors/{0}");

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

using var scope = app.Services.CreateScope();
var services = scope.ServiceProvider;
var context = services.GetRequiredService<AppDbContext>();
var logger = services.GetRequiredService<ILogger<Program>>();

try
{
    await context.Database.MigrateAsync();
    await AppDbSeedData.SeedAll(context);
}
catch (Exception ex)
{
    logger.LogError(ex, "An error occured during migration");
}

app.Run();

所以现在我没有任何想法，有人知道哪里可能有问题吗？

Answer 1

您的

appsettings.json

 文件中可能缺少“主机”属性

它应该看起来像这样：

"ConnectionStrings": {
  "DefaultConnection": "Host=your_host; Port=your_port; User Id=postgres; Password=your_password; Database=your_database_name"
}