Error: "Mappings only supports mapping objects."

jbaggaley

What does this error mean in the context of trying to create a custom column mapping. I figure it is something to do with the primary key field because in your widget example:

// Create the mappings between a certain table 
                
TableMapping tableMapping = (TableMapping)mappings.Join(db1.Tables["[dbo].[WidgetPrices]"], db2.Tables["[dbo].[WidgetPrices]"]);                 
  
// Set the custom comparison key for the table                 
tableMapping.MatchingMappings.Clear();                
tableMapping.MatchingMappings.Add(tableMapping.FieldMappings["WidgetID"]);  
tableMapping.RefreshMappingStatus();      
             
// Set the where clause for the comparison              
tableMapping.Where = new WhereClause("Active = 'Y'");    
  
// Peform the comparison                
session.CompareDatabases(db1, db2, mappings);

changing "widgetid" to "price" produces the same error.

On my table, I have two columns, a primary key value and a secondary key value which I want to compare them against a table that has a combination of those two as a composite primary key but get this error.
What do I need to change (in sql or my code) to fix this issue - even for the widget sample if i wanted to compare price columns for some reason?

Also, can you confirm if the following are identical because in the help file they are next to each other not a subset of eachother.

TableMappings mappings = new TableMappings();                                 
TableMapping tableMapping = (TableMapping)mappings.Join(

and

SchemaMappings mappings = new SchemaMappings(); 
TableMapping tableMapping =(TableMapping) mappings.TableMappings.Join(

Am I right in presuming that they are interchangeable?

Thanks

Jon

jbaggaley

I know is is possible to map tables based on fields that are not just index fields using comparison keys because the DataCompare gui lets me do it but I cannot quite work out how to do the same thing through the toolkit...

jbaggaley

I was passing in values from a dataset to set the table name and field names. However, the values were not being converted to a string first which didn't give a compile error.
For future reference to solve:-
make sure the field name is spelt correctly and that it is being passed as a string.
As for my other question, the tablemapping and structure.tablemappings do seem functionally identical even though they appear next to each other in the help.

Hope this helps someone....

Jon

david connell

Hi Jon,
As you found out the fields are case sensitive.
I believe that Schema mappings are probably what you want to use.
Schema mappings are a superset of TableMappings.

I would recomend that you let SQL Data Compare Engine setup the default mappings for you and then afterwards customize it for you requirements. eg

private static void AddWhereClause(SchemaMappings mappings)
{
  foreach (TableMapping mapping in mappings.TableMappings) 
  { 
    if ( (mapping.Obj1.FullyQualifiedName=="[dbo].[WidgetPrices]") &&
	     (mapping.Obj1.ObjectType == ObjectType.Table) )
   { 
      mapping.MatchingMappings.Clear();                
      //tableMapping.MatchingMappings.Add(mapping.FieldMappings["RecordID"]);  
      //tableMapping.MatchingMappings.Add(mapping.FieldMappings["WidgetID"]);  
      mapping.MatchingMappings.Add(mapping.FieldMappings["Price"]);
      mapping.RefreshMappingStatus();      
      mapping.Where = new WhereClause("Price>=51"); 
      mapping.Include=true; 
    }
    else
    {
      mapping.Include = false;
    }
  }
}
public void myCode()
{
...

  SchemaMappings mappings1 = new SchemaMappings();
  mappings1.CreateMappings(db1, db2);
  AddWhereClause(mappings1);
....
}

if you want to use one of the indexes then call

mapping.UseIndexForMapping(mapping.IndexMappings[0]);
mapping.RefreshMappingStatus();

or if you know the indexes name, you could use

mapping.UseIndexForMapping("IX_WidgetPrices");
mapping.RefreshMappingStatus();

Hope that helps
David

jbaggaley

Now if this example can somehow make it's way into the next version of the documentation....