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Question

我有这个实体：

namespace Entities.dbo
{
    [TableName("tbl_question")]
    public class Question : AbstractEntity
    {
        [MapField("c_from")]
        [Association(CanBeNull = false, OtherKey = "id", ThisKey = "c_from")]
        public User From { get; set; }

        [MapField("c_to")]
        [Association(CanBeNull = false, OtherKey = "id", ThisKey = "c_to")]
        public Band To { get; set; }

    }
}

通向Band实体：

namespace Entities.dbo
{
    [TableName("tbl_band")]
    public class Band : AbstractEntity
    {
        [MapField("name")]
        public string Name { get; set; }

        [MapField("frontman")]
        [Association(CanBeNull = false, ThisKey = "frontman", OtherKey = "id")]
        public User Frontman { get; set; }

    }
}

但是当我试图得到这样的问题时：

public static List<Question> GetQuestions(Band band)
        {
            using (var db = new MyDbManager())
            {
                try
                {

                    var l = db.GetTable<Question>().Where(x => x.To == band).ToList();

                    return l;
                }catch(Exception e)
                {

                    return null; 
                }
            }

我得到了一个例外：

Association key 'c_to' not found for type 'Entities.dbo.Question.

你知道问题出在哪里吗？

我知道表中的tbl_question是c_to列。

谢谢

Answer 1

ThisKey属性表示定义关联一侧的关键字段(以逗号分隔)。实体类字段，不是数据库表字段！在您的情况下，您必须：

1. Define field in the Question entity for ThisKey property:

[MapField("c_to")]
public int BandId { get; set; }

2. Define field in the Band entity for OtherKey property:

[MapField("id")]
public string BandId { get; set; }

3. Rewrite To property in the Question entity:

[Association(CanBeNull = false, OtherKey = "BandId", ThisKey = "BandId")]
public Band To { get; set; }