EF 4.4 InverseProperty does not quite inverse

问题

This might really be something obvious but I'm not sure why my InverseProperty annotation does not work the other way.

I have this 2 classes (simplified):

public class Cluster
{
    [Key]
    public int ClusterId { get; set; }

    [Required]
    [MaxLength(80, ErrorMessage = "DimensionCluster Name cannot be more than 80 characters in length.")]
    [Display(Name = "DimensionCluster Name")]
    public string ClusterName { get; set; }

    [InverseProperty("DimensionCluster")]
    public virtual IEnumerable<Dimension> Dimensions { get; set; }

}

public class Dimension
{
    [Key]
    public int DimensionId { get; set; }

    [Required]
    [MaxLength(80, ErrorMessage = "Dimension Name cannot be more than 80 characters in length.")]
    [Display(Name = "Dimension Name")]
    public string DimensionName { get; set; }

    [Required]
    [Display(Name = "Short Definition")]
    public string ShortDefinition { get; set; }

    [Required]
    [Display(Name = "DimensionCluster Name")]
    public int ClusterId { get; set; }

    [ForeignKey("ClusterId")]
    public virtual Cluster DimensionCluster { get; set; }


}

The InverseProperty annotation above does not work. I get:

The InversePropertyAttribute on property 'Dimensions' on type 'PDguide.Models.Cluster' is not valid. The property 'DimensionCluster' is not a valid navigation property on the related type 'System.Collections.Generic.IEnumerable`1[PDguide.Models.Dimension]'. Ensure that the property exists and is a valid reference or collection navigation property.

Tried a lot of MSDN documents and SO answers. And I finally tried it the other way (code below), and it worked!

public class Cluster
{
    [Key]
    public int ClusterId { get; set; }

    [Required]
    [MaxLength(80, ErrorMessage = "DimensionCluster Name cannot be more than 80 characters in length.")]
    [Display(Name = "DimensionCluster Name")]
    public string ClusterName { get; set; }

    public virtual IEnumerable<Dimension> Dimensions { get; set; }

}

public class Dimension
{
    [Key]
    public int DimensionId { get; set; }

    [Required]
    [MaxLength(80, ErrorMessage = "Dimension Name cannot be more than 80 characters in length.")]
    [Display(Name = "Dimension Name")]
    public string DimensionName { get; set; }

    [Required]
    [Display(Name = "Short Definition")]
    public string ShortDefinition { get; set; }

    [Required]
    [Display(Name = "DimensionCluster Name")]
    public int ClusterId { get; set; }

    [ForeignKey("ClusterId")]
    [InverseProperty("Dimensions")]
    public virtual Cluster DimensionCluster { get; set; }

}

I have read somewhere (I could not find that reference now, or I may have inferred it incorrectly) that you can specify the InverserProperty annotation on either end of the relationship. But that does not seem to be the case here?

Am I right in my understanding that InverseProperty should work with either property?

回答1:

You are right. In Programming Entity Framework: Code First by Lerman and Miller it says on page 72

You can place the annotations on either end of the relationship (or both ends if you want).

When I look in the current EF source, it seems that only collection properties of type ICollection<T> are recognized as valid inverse properties. So I think that changing the type of your Dimensions property into ICollection<Dimension> would allow you to put the InversePropertyAttribute there as well.

来源：https://stackoverflow.com/questions/18625631/ef-4-4-inverseproperty-does-not-quite-inverse

标签

entity-framework

data-annotations