Runtime error when Converting sObject to Account (typecasting)

Question

I'm working on a SOAP integration (.NET C#) to Salesforce and I am facing a problem when I try to get results from Salesforce.

To do this I'm using the next example code of the Salesforce walkthrough:

private void querySample()
{
     String soqlQuery = "SELECT FirstName FROM Account";         
     QueryResult qr = binding.query(soqlQuery);

     if (qr.size > 0)
     {               
         while (!done)
         {              
             sObject[] records = qr.records;
             for (int i = 0; i < records.Length; i++)
             {
                 Account con = (Account)records[i];                     
             }

             if (qr.done)
             {
                 done = true;
             }
             else
             {
                 qr = binding.queryMore(qr.queryLocator);
             }
           }
        }
        else
        {
           Console.WriteLine("No records found.");
        }
     }
     catch (Exception ex)
     {
        Console.WriteLine("\nFailed to execute query succesfully," +
            "error message was: \n{0}", ex.Message);
     }

The problem is in

Account con = (Account)records[i];

When it tries to cast the sObject to the Account I get a runtime error:

System.InvalidCastException: 'An object of type' SalesForceIn.SForce.sObject 'cannot be converted to type' SalesForceIn.SForce.Account '.'

Why I am getting this error? Do I need to create my own converter? Maybe be it's related to wsdl problem?

Thanks in advance. Regards.

Edit: @sfdcfox I'm using Enterprise WSDL because when I export the Partner I don't have the entities like Account in the Wsdl definition. Thank you.

@Keith C Yes I have the correct using in both. Thank you.

Answer 1

I tried running the SOAP based Account query against my DEV org.

To do this I imported the Enterprise WSDL as a Web Reference, rather than the newer default of a Service Reference.

After importing the Enterprise WSDL I needed to update the generated Reference.cs proxy classes for public ListViewRecordColumn[][] records. See Importing the Salesforce Winter 15 Partner API to .NET.

Something that became apparent from trying your SOQL query.

SELECT FirstName FROM Account

It appears you are using Person Accounts as a standard org doesn't have Account.FirstName as a field.

When I changed the query to SELECT Name FROM Account it worked fine against my org.

Are you running the SOQL query against the org that generated the Enterprise WSDL? If not, it will likely fail. That is the thing about the Enterprise WSDL - it will only work against the org it was generated from (or one with an identical schema).