无法映射属性“ PropertyName”，因为它的类型为“ List< decimal>” [英] The property 'PropertyName' could not be mapped, because it is of type 'List<decimal>'

问题描述

当我尝试使用EntityFramework Core创建数据库时遇到了这个问题：

I got this problem when I try to create the database with EntityFramework Core:

属性'Rating.RatingScores'不能为已映射，因为它的类型为列表，而不是受支持的原始类型或有效实体类型。要么显式映射此属性，要么使用'[NotMapped]'属性或通过'OnModelCreating'中的'EntityTypeBuilder.Ignore'忽略它。

The property 'Rating.RatingScores' could not be mapped, because it is of type 'List' which is not a supported primitive type or a valid entity type. Either explicitly map this property, or ignore it using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

这是课程：

public class Rating
{
    public int Id { get; set; }

    public List<decimal> RatingScores { get; set; }

    public decimal Score
    {
        set => Score = value;
        get => Math.Round(RatingScores.Sum() / RatingScores.Count, 1);
    }
}

推荐答案

如果Rating类有多个RatingScores，您具有一对多关系，并且RatingScores属性需要它自己的表，因此需要创建一个新类。

If the Rating class has multiple RatingScores you have a one-to-many relationship and the RatingScores property needs its own table, you therefore need to create a new class.

Class RatingScore 
{
  public int Id { get; set; }
  public decimal RtSc { get; set; }
}

然后，Rating属性将如下所示：

Then the Rating property will look like this:

public List<RatingScore> MyRatingScores { get; set; }

但是，如果每个Rating具有一个RatingScore，则您的财产不应是集合。

However if each Rating has one RatingScore, your property should not be a collection.

public RatingScore MyRatingScore { get; Set; }

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