Question

LINQ to EF：

 db.ReadonlyQuery<Transaction>()
     .Select(t => new ACurrentDayInfo
         {
              OrderId = t.TransactionIdentifier,
              OrderTime = t.TransactionTime,
              UserName = JsonConvert.DeserializeObject<UserInfo>(t.UserInfo).RealName ?? ""
         })
     .ToListAsync();

t.UserInfo是表格字段中每个记录中的{"RealName ":"XY"}的json字符串。如何将其转换为服务器查询？

Answer 1

使用像这样的getter扩展你的ACurrentDayInfo课程

class  ACurrentDayInfo
{
    public string UserName
    {
        get
        {
            return JsonConvert.DeserializeObject<UserInfo>(UserInfo).RealName ?? "";
        }
    }
}

并修改您的查询：

db.ReadonlyQuery<Transaction>()
                    .Select(t => new ACurrentDayInfo
                    {
                        OrderId = t.TransactionIdentifier,
                        OrderTime = t.TransactionTime,
                        UserInfo = t.UserInfo
                    }).ToListAsync();

Answer 2

在EF Dbcontext中，不支持在查询中使用cast json，你需要修复相同的内容：

var listData = db.ReadonlyQuery<Transaction>()
                        .Select(t => new ACurrentDayInfo
                        {
                            OrderId = t.TransactionIdentifier,
                            OrderTime = t.TransactionTime,

                            UserInfo = t.UserInfo
                        }).ToListAsync();

foreach (var item in listData)
{
    item.UserName = JsonConvert.DeserializeObject<UserInfo>(t.UserInfo).RealName ?? "" 
}

LINQ to Entities无法识别NotSupportedException方法

2 个答案: