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LINQ to Entities does not recognize the method 'System.String get_Item (System.String)',

How can I solve this problem?

Here is my code:

    DateTime dtInicio = new DateTime();
    DateTime dtFim = new DateTime();
    Int32 codStatus = 0;

    if(!string.IsNullOrEmpty(collection["txtDtInicial"]))
        dtInicio = Convert.ToDateTime(collection["txtDtInicial"]);
    if(!string.IsNullOrEmpty(collection["txtDtFinal"]))
        dtFim = Convert.ToDateTime(collection["txtDtFinal"]);
    if (!string.IsNullOrEmpty(collection["StatusCliente"]))
        Convert.ToInt32(collection["StatusCliente"]);

    var listCLientResult = (from c in db.tbClientes
                           orderby c.id
                            where (c.effdt >= dtInicio || string.IsNullOrEmpty(collection["txtDtInicial"]) &&
                                 (c.effdt <= dtFim || string.IsNullOrEmpty(collection["txtDtFinal"])) &&
                                 (c.cod_status_viagem == codStatus || string.IsNullOrEmpty(collection["StatusCliente"])))
                                 select c);
    return View(listCLientResult);

The error I am getting is:

LINQ to Entities does not recognize the method 'System.String get_Item (System.String)', which can not be converted into an expression of the repository.

like image 510
mcamara Avatar asked Apr 14 '12 19:04

mcamara


2 Answers

Linq queries performed against a database are translated to SQL before they can be executed; but collection["txtDtInicial"] can't be translated to SQL, because there is no equivalent SQL syntax, and anyway the database doesn't have access to collection. You need to extract collection["txtDtInicial"] to a variable first, and use only this variable in the query.

Here's what I would do:

DateTime dtInicio = DateTime.MinValue;
DateTime dtFim = DateTime.MaxValue;
Int32 codStatus = 0;

if(!string.IsNullOrEmpty(collection["txtDtInicial"]))
    dtInicio = Convert.ToDateTime(collection["txtDtInicial"]);
if(!string.IsNullOrEmpty(collection["txtDtFinal"]))
    dtFim = Convert.ToDateTime(collection["txtDtFinal"]);
if (!string.IsNullOrEmpty(collection["StatusCliente"]))
    codStatus = Convert.ToInt32(collection["StatusCliente"]);

var listCLientResult = (from c in db.tbClientes
                       orderby c.id
                        where (c.effdt >= dtInicio) &&
                             (c.effdt <= dtFim) &&
                             (c.cod_status_viagem == codStatus)
                             select c);
return View(listCLientResult);

By initializing dtInicio and dtFim to MinValue and MaxValue, you don't need to check whether they are defined in the query.

like image 148
Thomas Levesque Avatar answered Nov 14 '22 10:11

Thomas Levesque


The Linq query is ultimately transformed into an SQL query and LINQ doesn't know what to do with Session["UserName"] (that gets the "UserName" item).

A common way to workaround this is just to use a local variable to which you'll assign Session["UserName"] and that you'll use in your Linq query...

like

string loggedUserName = Session["LogedUsername"].ToString();
var userdetail = dc.faculties.Where(a => a.F_UserName.Equals(loggedUserName)).FirstOrDefault();

reference http://mvc4asp.blogspot.in/

like image 10
ravi saini Avatar answered Nov 14 '22 10:11

ravi saini