我遇到一个使用网格视图列智能搜索工具的错误。这里我有多列varchar，int和nullable所以。我创建一个像FilterColumn这样的辅助方法，它接受两个参数（ColumnName，SearchText）。现在我在使用int值进行过滤时遇到了一个问题。
这是方法：
public static class Helper
{
public static IQueryable<T> FilterForColumn<T>(this IQueryable<T> queryable, string colName, string searchText)
{
if (colName != null && searchText != null)
{
var parameter = Expression.Parameter(typeof(T), "m");
var propertyExpression = Expression.Property(parameter, colName);
System.Linq.Expressions.ConstantExpression searchExpression = null;
System.Reflection.MethodInfo containsMethod = null;
// this must be of type Expression to accept different type of expressions
// i.e. BinaryExpression, MethodCallExpression, ...
System.Linq.Expressions.Expression body = null;
Expression ex1 = null;
Expression ex2 = null;
Expression converted = null;
switch (colName)
{
// section for int properties
case "party_id":
case "type_id":
case "status_id":
case "category_id": //here problem occurs
Int32 _int = Convert.ToInt32(searchText);
searchExpression = Expression.Constant(_int);
containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
// section for int? properties
case "country_id":
case "state_id":
Int32? _int1 = Convert.ToInt32(searchText);
searchExpression = Expression.Constant(_int1);
converted = Expression.Convert(searchExpression, typeof(object));
containsMethod = typeof(Int32?).GetMethod("Equals", new[] { typeof(Int32?) });
body = Expression.Call(propertyExpression, containsMethod, converted);
break;
// section for DateTime? properties
case "PublishDate":
case "Birth_date":
case "Anniversary_date":
case "Profile_Updated_datetime":
case "CompletedOn":
DateTime currentDate = DateTime.ParseExact(searchText, "dd/MM/yyyy", null);
DateTime nextDate = currentDate.AddDays(1);
ex1 = Expression.GreaterThanOrEqual(propertyExpression, Expression.Constant(currentDate, typeof(DateTime?)));
ex2 = Expression.LessThan(propertyExpression, Expression.Constant(nextDate, typeof(DateTime?)));
body = Expression.AndAlso(ex1, ex2);
break;
// section for DateTime properties
case "Created_date":
case "Register_Date":
DateTime currentDate1 = DateTime.ParseExact(searchText, "dd/MM/yyyy", null);
DateTime nextDate1 = currentDate1.AddDays(1);
ex1 = Expression.GreaterThanOrEqual(propertyExpression, Expression.Constant(currentDate1));
ex2 = Expression.LessThan(propertyExpression, Expression.Constant(nextDate1));
body = Expression.AndAlso(ex1, ex2);
break;
default:
searchExpression = Expression.Constant(searchText);
containsMethod = typeof(string).GetMethod("Contains", new[] { typeof(string) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
}
var predicate = Expression.Lambda<Func<T, bool>>(body, new[] { parameter });
return queryable.Where(predicate);
}
else
{
return queryable;
}
}
}
这是我的搜索按钮代码，我如何将列值和搜索值传递给FillGrid：
protected void btnsearch_Click(object sender, System.EventArgs e)
{
if (DDL_Column_List.SelectedItem.Value.Equals("19"))
{
RegularExpressionValidator5.Enabled = true;
}
if (Page.IsValid)
{
using (DataClassesDataContext db = new DataClassesDataContext())
{
System.Threading.Thread.Sleep(2000);
if (DDL_Column_List.SelectedItem.Value != "-1" && txtsearch.Text.Trim() != "")
{
switch (DDL_Column_List.SelectedItem.Text.ToString())
{
case "Name":
Session["ColumnName"] = "Name";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Type":
Session["ColumnName"] = "type_id";
Session["SearchText"] = db.PartyTypes.Where(t => t.typename.Contains(txtsearch.Text.Trim())).Select(t => t.Id).SingleOrDefault().ToString();
break;
case "Owner Name":
Session["ColumnName"] = "Ownername";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Owner Mobile":
Session["ColumnName"] = "Ownermob";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Contact Person Name":
Session["ColumnName"] = "ContactPerson";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Contact Person Mobile":
Session["ColumnName"] = "ContactPersonmob";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Phone":
Session["ColumnName"] = "Phone";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Mobile":
Session["ColumnName"] = "Mobile";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Room":
Session["ColumnName"] = "Room";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Building":
Session["ColumnName"] = "Build";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Road":
Session["ColumnName"] = "Road";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Area":
Session["ColumnName"] = "Area";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "City":
Session["ColumnName"] = "City";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Country":
Session["ColumnName"] = "country_id";
Session["SearchText"] = db.Countries.Where(c => c.Country_name.Equals(txtsearch.Text.Trim())).Select(c => c.Id).SingleOrDefault().ToString();
break;
case "State":
Session["ColumnName"] = "state_id";
Session["SearchText"] = db.States.Where(s => s.state_name.Equals(txtsearch.Text.Trim())).Select(s => s.Id).SingleOrDefault().ToString();
break;
case "Email":
Session["ColumnName"] = "Email";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Remark":
Session["ColumnName"] = "Remark";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Username":
Session["ColumnName"] = "Username";
Session["SearchText"] = txtsearch.Text.Trim();
break;
case "Register Date":
Session["ColumnName"] = "Register_Date";
Session["SearchText"] = txtsearch.Text.Trim();
break;
}
}
else
{
Session["SearchText"] = null;
Session["ColumnName"] = null;
}
this.FillGrid((String)Session["StartAlpha"] ?? null, (int)Session["GroupByENTYPE"] , (String)Session["ColumnName"] ?? null, (String)Session["SearchText"] ?? null);
UpdatePanel10.Update();
MPE.Show();
}
}
}
这里我在使用int值时遇到一个问题，当用户输入一些字符串值时，例如＆＃39; Customer＆＃39; 然后我必须找出哪个id属于这个文本，我将这个id传递给session，然后我的helper方法过滤它。现在我在type_id情况下遇到问题。这里抛出一个错误：
Server Error in '/CRM' Application.
Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)'
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.ArgumentException: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)'
Source Error:
Line 42: converted = Expression.Convert(searchExpression, typeof(object));
Line 43: containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
Line 44: body = Expression.Call(propertyExpression, containsMethod, searchExpression);
Line 45: break;
Line 46: case "country_id":
Source File: f:\CRM\App_Code\Helper.cs Line: 44
Stack Trace:
[ArgumentException: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)']
System.Linq.Expressions.Expression.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arg, ParameterInfo pi) +4189655
System.Linq.Expressions.Expression.ValidateArgumentTypes(MethodBase method, ExpressionType nodeKind, ReadOnlyCollection`1& arguments) +132
System.Linq.Expressions.Expression.Call(Expression instance, MethodInfo method, IEnumerable`1 arguments) +71
System.Linq.Expressions.Expression.Call(Expression instance, MethodInfo method, Expression[] arguments) +29
Helper.FilterForColumn(IQueryable`1 queryable, String colName, String searchText) in f:\CRM\App_Code\Helper.cs:44
Staff_Raise_Ticket.FillGrid(String StartAlpha, Int32 GroupByENTYPE, String ColumnName, String SearchText) in f:\CRM\Staff\Raise_Ticket.aspx.cs:249
Staff_Raise_Ticket.btnsearch_Click(Object sender, EventArgs e) in f:\CRM\Staff\Raise_Ticket.aspx.cs:1342
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1
我不明白这里出了什么问题......
答案 0 :(得分：1)
错误中的代码与您Helper方法的代码不匹配。错误报告：
converted = Expression.Convert(searchExpression, typeof(object));
containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
case "country_id":
当我在代码中搜索case "country_id":时，我会找到这些行：
case "category_id": //here problem occurs
Int32 _int = Convert.ToInt32(searchText);
searchExpression = Expression.Constant(_int);
containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
// section for int? properties
case "country_id":
错误中报告的第一行代码
converted = Expression.Convert(searchExpression, typeof(object));
未出现在您发布的代码中，可能是错误的来源：您尝试调用的方法需要Int32参数object参数，因为您是将searchExpression（可能已经有正确类型，Int32）转换为object类型。确保您正在查看的代码是正在执行的代码，并删除转换为object。