实体框架在实例化新实体时生成索引错误

Question

To contextualize my problem I am using C # VS 2017 + EF 6 (DB First) + SQL Server.

Please let me explain the problem: I am instantiating a class to add a record to it. However, in this particular class, when I instantiate, I immediately get an index error out of range. It is an error of type System.ArgumentOutOfRangeException .

Details:

1. I didn't add values, just instantiated the entity.
2. For testing purposes I removed all relationships from the table involved and the problem continues.
3. I already deleted the table and recreated it in both SQL and EDMX.

Has anyone ever experienced this? Any suggestions?

My code:

     using (coletasEntities ctx = new coletasEntities())
     {
           // error happens on line below
           coleta_nota_problema erro = new coleta_nota_problema();

           erro.descricao = msg.Substring(0, 250);
           erro.id_coleta_nota = id;

           ctx.coleta_nota_problema.Add(erro);
           ctx.SaveChanges();
     }

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated from a template.
//
//     Manual changes to this file may cause unexpected behavior in your application.
//     Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

namespace Coletas
{
    using System;
    using System.Collections.Generic;

    public partial class coleta_nota_problema
    {
        public int id_coleta_nota_problema { get; set; }
        public int id_coleta_nota { get; set; }
        public string descricao { get; set; }
    }
}

Answer 1

To isolate the problem, try assigning a hard coded value first and see if it the error goes away:

erro.descricao = "hello"; // any arbitrary text
erro.id_coleta_nota = 1000; // any arbitrary integer unique if this is the key
erro.id_coleta_nota_problema = 1000; // any arbitrary integer

As mentioned in the comments in your post, the following line is most probably the culprit:

erro.descricao = msg.Substring(0, 250);