EF Core中的一对一关系（一对一关系无法确定child/dependent端）

Question

我一直收到以下错误消息，但我似乎无法理解为什么会收到它。有趣的是，在添加迁移时我没有遇到任何错误，但每当我想使用上下文时我都会得到它。

The child/dependent side could not be determined for the one-to-one relationship between 'Block.JobBlock' and 'JobBlock.Block'. To identify the child/dependent side of the relationship, configure the foreign key property. If these navigations should not be part of the same relationship configure them without specifying the inverse.

一个Job可以有多个JobBlocks（一对多）；单个 Block 只能有一个 JobBlock （一对一）。所以基本上，JobBlock 是一个引用 table/entity，用于引用 Job 及其 Blocks。重要的是要提到 JobBlock 实体中的主键由两个键组成，因此使其成为复合主键。

有人可能会争辩说 Block 实体应该已经包含 IdJob 属性而 JobBlock 实体可以完全忽略，但有一些理由可以解释为什么它不应该以这种方式完成，所以让我们保持原样:)

型号：

public class Job : IEntity
{
    public Job()
    {
        JobBlocks = new HashSet<JobBlock>();
    }

    public Guid Id { get; set; } = Guid.NewGuid();
    public ICollection<JobBlock> JobBlocks { get; set; }
}

public class Block : IEntity
{
    public Guid Id { get; set; } = Guid.NewGuid();
    public JobBlock JobBlock { get; set; }
}


public class JobBlock : IEntity
{
    public Guid IdJob { get; set; }
    public Job Job { get; set; }

    public Guid IdBlock { get; set; }
    public Block Block { get; set; }
}

EF 配置：

public class JobConfiguration : IEntityTypeConfiguration<Job>
{
    public void Configure(EntityTypeBuilder<Job> builder)
    {
        builder.HasKey(p => p.Id);
        builder.Property(p => p.Id) .IsRequired() .ValueGeneratedNever();

        builder.HasMany(e => e.JobBlocks)
            .WithOne(e => e.Job)
            .HasForeignKey(p => p.IdJob);
    }
}

public class BlockConfiguration : IEntityTypeConfiguration<Block>
{
    public void Configure(EntityTypeBuilder<Block> builder)
    {
        builder.HasKey(p => p.Id);
        builder.Property(p => p.Id).IsRequired().ValueGeneratedNever();

        builder.HasOne(e => e.JobBlock)
            .WithOne(e => e.Block)
            .HasForeignKey<JobBlock>(p => new { p.IdJob, p.IdBlock });
    }
}

public class JobBlockConfiguration : IEntityTypeConfiguration<JobBlock>
{
    public void Configure(EntityTypeBuilder<JobBlock> builder)
    {
        builder.HasKey(p => new { p.IdJob, p.IdBlock });
        builder.Property(p => p.IdJob).IsRequired();
        builder.Property(p => p.IdBlock).IsRequired();

        builder.HasOne(e => e.Job)
            .WithMany(e => e.JobBlocks)
            .HasForeignKey(p => p.IdJob);

        builder.HasOne(e => e.Block)
            .WithOne(e => e.JobBlock)
            .HasForeignKey<JobBlock>(p => new { p.IdJob, p.IdBlock });
    }
}

Answer 1

问题出在您的 Block 和 JobBlock 配置中。根据您的要求，这两个配置应该如下：

public class BlockConfiguration : IEntityTypeConfiguration<Block>
{
    public void Configure(EntityTypeBuilder<Block> builder)
    {
        builder.HasKey(p => p.Id);
        builder.Property(p => p.Id).IsRequired().ValueGeneratedNever();

        builder.HasOne(e => e.JobBlock)
            .WithOne(e => e.Block)
            .HasForeignKey<JobBlock>(p => p.IdBlock); // <--- Here it is
    }
}
public class JobBlockConfiguration : IEntityTypeConfiguration<JobBlock>
{
    public void Configure(EntityTypeBuilder<JobBlock> builder)
    {
        builder.HasKey(p => new { p.IdJob, p.IdBlock });

        // Key property is always required. You don't need to specify it explicitly.

        // You don't need to need specify one-one-one configuration
        //  between `Job and Block` and between `Block and JobBlock` in
        //  two places. You need to specify
        //  it only one place. That's why I have removed these from here.
    }
}

EF Core中的一对一关系（一对一关系无法确定child/dependent端）

One-to-one relationship in EF Core (The child/dependent side could not be determined for the one-to-one relationship)

entity-framework

entity-framework-core

ef-fluent-api

.net-core

entity-framework-core-2.2