使用 Entity Framework 时出现 InvalidCastException

Question

我正在尝试在对话中保存用户列表 class，但在执行 POST 时收到 InvalidCastException。

这是我的用户 class:

public class User
{
    [Key]
    [DataMember]
    public String Email { get; set; }

    [DataMember]
    public String Password { get; set; }

    [DataMember]
    public Boolean Admin { get; set; }

    public User(String email, String password, Boolean admin)
    {
        Email = email;
        Password = password;
        Admin = admin;
    }
}

这是我的对话class:

[DataContract]
public class Conversation
{
    [Key]
    [DataMember]
    public string Key { get; set; }
    [DataMember]
    public string ConversationName { get; set; }
    [DataMember]
    public string Administrator { get; set; }
    [DataMember]
    [ForeignKey("Email")]
    public List<User> Members { get; set; }

    public Conversation(string key, string name, string admin, List<User> members)
    {
        Key = key;
        ConversationName = name;
        Administrator = admin;
        Members = members;
    }

    public Conversation()
    {

    }
}

这是对话控制器：

POST:

    [HttpPost]
    public async Task<IHttpActionResult> PostConversation(Conversation convo)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        foreach (var user in convo.Members)
        {
            db.Entry(user).State = EntityState.Unchanged;
        }

        db.Conversations.Add(convo);
        await db.SaveChangesAsync();

        return CreatedAtRoute("DefaultApi", new { name = convo.Key }, convo);
    }

获取：

[HttpGet]
public IQueryable<Conversation> GetConversations()
{
    return db.Conversations;
}

编辑 Post 声明：

{
"Key": "123",
"ConversationName": "Test",
"Administrator": "Ken",
"Members": [{"Email": "y@12.com","Password" : "Passw-1", "Admin" : "true"},
            {"Email": "y@123.com","Password" : "Passw-1", "Admin" : "false"}]
}

我得到的错误是：

"ExceptionMessage": "Unable to cast object of type 'System.Collections.Generic.List`1[AcademicAssistant.Models.User]' to type 'AcademicAssistant.Models.User'.",

Answer 1

你的模型有误。由于 Conversation 和 User 之间存在 N:N 关系，因此您需要从 Members 之前的对话中删除 ForeingKey 属性，并且需要添加 ICollection<Conversation> Conversation 属性在用户 class 中，或者更进一步，根据需要使用 FluentApi

配置关系

使用 Entity Framework 时出现 InvalidCastException

InvalidCastException when using Entity Framework

c#

http

entity-framework-5

asp.net-web-api2