如何在 entity framework 中配置与我自己创建的实体的多对多关系

Question

我有一些 classes:

public class Values : Entity
    {
        [Key]
        public int Values_ID { get; set; }    
        [Required]
        public string Values_Name { get; set; }    
        [Required]
        public int ValuesNumeric { get; set; }    
        public virtual ICollection<ValuesMetrics> ValuesMetrics { get; set; }
    }

public class GQMetric : Entity
    {
        [Key]
        public int GQMetric_ID { get; set; }

        [Required]
        public string GQMetricName { get; set; }
        [Required]
        public int Importance_ID { get; set; }

        public virtual List<GQMetricsQuestions> GQMetricsQuestions { get; set; }
        public virtual ICollection<ValuesMetrics> ValuesMetrics { get; set; }

        public virtual ImportanceScale ImportanceScale { get; set; }
    }

我需要为我自己创建的 class ValuesMetrics 创建多对多关系，而不是由 entity framework 自动生成 table。我已经尝试了很多解决方案 here, here and here 但其中 none 没有奏效。最终，我这样做了：

public class ValuesMetrics : Entity
    {
        public int GQMetric_ID { get; set; }
        public int Value_ID { get; set; }

        public virtual GQMetric GQMetric { get; set; }
        public virtual Values Values { get; set; }
    }

FluentAPI:

modelBuilder.Entity<ValuesMetrics>()
               .HasKey(c => new { c.GQMetric_ID, c.Value_ID });

            modelBuilder.Entity<GQMetricsQuestions>()
               .HasKey(c => new { c.GQMetric_ID, c.Question_ID });

但创建table (ValuesMetrics) 有过度关系(GQMetrics_GQMetric_ID)。我只需要来自 Values 和 GQMetrics table 的两个主键

你能告诉我如何解决这个问题吗？感谢您的帮助！

Answer 1

应用了来自您已引用的 link 的@Esteban 的解决方案：Create code first, many to many, with additional fields in association table

基本上我做了以下三处改动：

使用 POCO 实体而不是从 Entity class
删除了 EF 属性，因为无论如何我们都会使用 fluent API
更改流畅 API 配置

结果代码：

public class MyContext : DbContext
{
    public DbSet<Values> Values { get; set; }
    public DbSet<GQMetric> GqMetric { get; set; }
    public DbSet<ValuesMetrics> ValuesMetrics { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Values>().HasKey(values => values.Values_ID);
        modelBuilder.Entity<GQMetric>().HasKey(metric => metric.GQMetric_ID);

        modelBuilder
            .Entity<ValuesMetrics>()
            .HasKey(valuesMetrics => new
            {
                valuesMetrics.Value_ID,
                valuesMetrics.GQMetric_ID
            });

        modelBuilder
            .Entity<ValuesMetrics>()
            .HasRequired(valuesMetrics => valuesMetrics.Values)
            .WithMany(valueMetrics => valueMetrics.ValuesMetrics)
            .HasForeignKey(valueMetrics => valueMetrics.Value_ID);

        modelBuilder
            .Entity<ValuesMetrics>()
            .HasRequired(valuesMetrics => valuesMetrics.GQMetric)
            .WithMany(valueMetrics => valueMetrics.ValuesMetrics)
            .HasForeignKey(valueMetrics => valueMetrics.GQMetric_ID);

        base.OnModelCreating(modelBuilder);
    }
}

public class Values
{
    public int Values_ID { get; set; }
    public string Values_Name { get; set; }
    public int ValuesNumeric { get; set; }
    public virtual ICollection<ValuesMetrics> ValuesMetrics { get; set; }
}

public class GQMetric
{
    public int GQMetric_ID { get; set; }
    public string GQMetricName { get; set; }

    public virtual ICollection<ValuesMetrics> ValuesMetrics { get; set; }
}

public class ValuesMetrics
{
    public int GQMetric_ID { get; set; }
    public int Value_ID { get; set; }

    public virtual GQMetric GQMetric { get; set; }
    public virtual Values Values { get; set; }
}

如何在 entity framework 中配置与我自己创建的实体的多对多关系

How can I configure many-to-many relationship to my own created entity in entity framework

c#

sql-server

many-to-many

entity-framework

ef-code-first