LINQ - Specified cast is not valid RSS

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  MayLam

  Participant

  951 Points

  573 Posts

  LINQ - Specified cast is not valid

  Jul 21, 2010 10:26 PM|LINK

  Hi everyone,
  
  I having a problem with linq. The following line

   

  Emp objEmp = tblEmps.SingleOrDefault(p => p.empno ==Int32.Parse(this.txtEmpno.Text));

   

  generates the following error message:
  
  System.InvalidCastException was caught
  Message=Specified cast is not valid.
  Source=System.Data.Linq
  StackTrace:
  at System.Data.Linq.SqlClient.SqlProvider.Execute(Exp ression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult)
  at System.Data.Linq.SqlClient.SqlProvider.ExecuteAll( Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries)
  at System.Data.Linq.SqlClient.SqlProvider.System.Data .Linq.Provider.IProvider.Execute(Expression query)
  at System.Data.Linq.Table`1.System.Linq.IQueryProvide r.Execute[TResult](Expression expression)
  at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source, Expression`1 predicate)
  at SampleCS.CRUD.btnSearch_Click(Object sender, EventArgs e) in p:\JIMMY PROGRAMMING IN 2010\Linq_Samples\CRUD.aspx.cs:line 48
  InnerException:
  
  ------------------
  
  Please let me know how to fix this problem. Thanks.
  
  Cecilia

  <div></div>

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  • Moved by mbanavige on Jul 21, 2010 10:27 PM
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  sansan

  All-Star

  53942 Points

  8147 Posts

  Re: LINQ - Specified cast is not valid

  Jul 21, 2010 10:35 PM|LINK

  Check if the empno is an integer to compare

  and make sure you check for null values in the TextEmpno.Text

  if the text is blank, it will fail in casting to integer

  a quick solution for that will be using Convert.ToString on both sides which again depends on your scenario

  as 

  Convert.ToString(p.empno)==txtEmpno.Text

  correct me if I am wrong

  
  

  Santhosh
  • Marked as answer by Hong-Gang Chen - MSFT on Jul 28, 2010 11:22 AM