有沒有辦法以編程方式檢查 Entity Framework Core 中掛起的模型更改？

Question

我目前正在為 ASP.NET Core WebAPI 開發設置團隊環境，結合 GitLab CI 使用 xUnit 進行單元測試。 對於數據庫通信，我們使用 EF Core。

對於 EF Core，我們將使用 Code First Migrations，我們擔心開發人員可能只會更新模型，而不會為其模型更改創建遷移。 因此，我們希望 CI 運行代碼庫中存在的所有遷移，將它們與代碼優先模型的當前狀態進行比較，並在代碼優先模型狀態不等於運行所有遷移所產生的狀態時失敗。

有沒有辦法做到這一點？ 我在 EF Core 文檔中找不到任何關於此的信息。

Answer 1

如果您使用的是 EF (core) 5，您將需要一個稍微不同的版本（也改編自@ErikEJ 示例代碼）

    [Fact]
    public void ModelDoesNotContainPendingChanges()
    {
        // Do not use the test database, the SQL Server model provider must be
        // used as that is the model provider that is used for scaffolding migrations.
        using var ctx = new DataContext(
            new DbContextOptionsBuilder<DataContext>()
                .UseNpgsql(DummyConnectionString)
                .Options);

        var modelDiffer = ctx.GetService<IMigrationsModelDiffer>();
        var migrationsAssembly = ctx.GetService<IMigrationsAssembly>();

        var dependencies = ctx.GetService<ProviderConventionSetBuilderDependencies>();
        var relationalDependencies = ctx.GetService<RelationalConventionSetBuilderDependencies>();

        var typeMappingConvention = new TypeMappingConvention(dependencies);
        typeMappingConvention.ProcessModelFinalizing(((IConventionModel)migrationsAssembly.ModelSnapshot.Model).Builder, null);

        var relationalModelConvention = new RelationalModelConvention(dependencies, relationalDependencies);
        var sourceModel = relationalModelConvention.ProcessModelFinalized(migrationsAssembly.ModelSnapshot.Model);

        var finalSourceModel = ((IMutableModel)sourceModel).FinalizeModel().GetRelationalModel();
        var finalTargetModel = ctx.Model.GetRelationalModel();

        var hasDifferences = modelDiffer.HasDifferences(finalSourceModel, finalTargetModel);
        if(hasDifferences)
        {
            var changes = modelDiffer.GetDifferences(finalSourceModel, finalTargetModel);
            Assert.True(false, $"{changes.Count} changes between migrations and model. Debug this test for more details");
        }

        Assert.False( hasDifferences );
    }

Answer 2

感謝@ErikEJ 的示例代碼，我能夠編寫以下完全符合我要求的測試：

    using FluentAssertions;
    using Microsoft.EntityFrameworkCore;
    using Microsoft.EntityFrameworkCore.Infrastructure;
    using Microsoft.EntityFrameworkCore.Migrations;
    using Xunit;

    /// <summary>
    /// Contains a test that verifies that the
    /// model does not contain any changes that are not included
    /// in the migrations.
    /// </summary>
    public class NoPendingModelChangesTest
    {
        private static readonly string DummyConnectionString = @"Server=localhost;Database=DoesNotExist;Trusted_Connection=True;";

        /// <summary>
        /// Tests that the current model does not contain any changes
        /// that are not contained in the database migrators.
        /// In other words: tests that the current model state equals the
        /// state that results from all the migrations combined.
        /// </summary>
        [Fact]
        public void ModelDoesNotContainPendingChanges()
        {
            // Do not use the test database, the SQL Server model provider must be
            // used as that is the model provider that is used for scaffolding migrations.
            using var ctx = new MyDatabase(
                new DbContextOptionsBuilder<MyDatabase>()
                    .UseSqlServer(DummyConnectionString)
                    .Options);

            var modelDiffer = ctx.GetService<IMigrationsModelDiffer>();
            var migrationsAssembly = ctx.GetService<IMigrationsAssembly>();

            var pendingModelChanges = modelDiffer
                .GetDifferences(
                    migrationsAssembly.ModelSnapshot?.Model,
                    ctx.Model);

            pendingModelChanges
                .Should()
                .BeEmpty(
                    because:
                        "the current model state should be equal to the state that results from all the migrations combined (try scaffolding a migration)");
        }
    }

Answer 3

對於 EF Core 6，來自@ErikEJ 的優秀 EF Core Power Tools：

var migrationsAssembly = _ctx.GetService<IMigrationsAssembly>();

var hasDifferences = false;
if (migrationsAssembly.ModelSnapshot != null) {
    var snapshotModel = migrationsAssembly.ModelSnapshot?.Model;

    if (snapshotModel is IMutableModel mutableModel) {
        snapshotModel = mutableModel.FinalizeModel();
    }

    snapshotModel = _ctx.GetService<IModelRuntimeInitializer>().Initialize(snapshotModel);
    hasDifferences = _ctx.GetService<IMigrationsModelDiffer>().HasDifferences(
        snapshotModel.GetRelationalModel(),
        _ctx.GetService<IDesignTimeModel>().Model.GetRelationalModel());
}

https://github.com/ErikEJ/EFCorePowerTools/blob/5a16c37c59be854605f3e81d3131011d96c96704/src/GUI/efpt30.core/EFCoreMigrationsBuilder.cs#L98