'System.Int16'类型的表达式不能用于返回类型'System.Object'

Question

public IQueryable<Users> SelectAdmin<TProp>(string sSortExpression, string sSortOrder ,long[] IAds, int iStart, int iEnd, long iId)
    {
        var param = Expression.Parameter(typeof(Users));
        var propExpression = Expression.Lambda<Func<Users, TProp>>(Expression.Property(param, sSortExpression), param);
        if (sSortOrder == "asc")
        {

            return objCouponUow.Repository<Users>().Entities.Where(x => x.UserGroup == 9 && x.Validate == 0 && x.Deleted == false && IAds.Contains(x.UserParent)).OrderBy(propExpression).Skip(iStart).Take(iEnd - iStart);
        }

    }

this is my function .. i Am getting the error in line :

  var propExpression = Expression.Lambda<Func<Users, TProp>>(Expression.Property(param, sSortExpression), param);

When the 'sSortExpression' which is a column in Users Table is of Type Varchar , No Problem But If its Int type.. Error Occurs Expression of type 'System.Int16' cannot be used for return type 'System.Object'

How can i Correct this problem?

Answer 1

有可能你没有给那里分配一个对象（sSortExpression），因为你说它是一个列，也许你将项目对象集合指定为int，所以得到了错误。

Answer 2

The problem here is that <Tprop> is not of the Type Int16 and the string you are passing which is a columnname of the type Int16

You can simply specify the <Tprop> wherever you are calling the function SelectAdmin<TProp> .

for example:

`SelectAdmin<int>(.......your parameters here);`

if the sSortExpression is of the Type int16. If it is of the type DateTime you can call like this

 SelectAdmin<DateTime>(.......your parameters here);