How to Resolve the 'LINQ to Entities does not recognize the method 'System.String ToString()' method' Error?

Troubleshooting the "LINQ to Entities doesn't recognize 'System.String ToString()'" Error

During MySQL to SQL Server data migration, a common error arises: LINQ to Entities fails to recognize the System.String ToString() method, preventing translation into a database query. This usually happens when comparing strings within a LINQ where clause.

The solution involves storing the string result of ToString() in a temporary variable before using it in the query. This effectively treats the string as a constant, enabling successful SQL translation. Here's how:

<code class="language-csharp">var strItem = item.Key.ToString();

IQueryable<entity> pages = from p in context.pages
                         where p.Serial == strItem
                         select p;</code>

By assigning item.Key.ToString() to strItem, the method's result becomes a constant value understood by the LINQ to Entities translator.

Alternatively, as suggested by Alex (reference needed for context), the SqlFunctions helper class offers specialized methods for LINQ to Entities queries, potentially eliminating the need for a temporary variable. Consult Alex's solution for detailed instructions on using SqlFunctions.

The above is the detailed content of How to Resolve the 'LINQ to Entities does not recognize the method 'System.String ToString()' method' Error?. For more information, please follow other related articles on the PHP Chinese website!