Hi,

I have an issue with one of my projects and I was wondering if someone could help me out.

We are doing a join on a number of tables and creating a collection. So

 
Create a collection of table1 then create a query joining table1 to table2 on a PK and thus adding a new column to our collection.

 
IF this query does not return a value we have an empty collection.... which is ok... BUT when we add an item to the collection and re-run the query the column is not there in the collection (If I close the form and thus re-create the collection the column is there with the appropriate data) is there anyway to create the join columns even if the join query returns no rows? or would it be best to do a count on the initial query result and then if it is "0" when I add the item destroy and re-create the collection?

Thanks,

 
Mark



 

Cheers Scott,

This is on the CF version, so views aren't an option, sorry for not mentioning. Think I will have to do it the other way!

Mark
 

Hi,

I think this is exactly what the CreateColumnsForBinding() is for, but the only instructions I can find in your API for it say that you should pass a string [] of properties. Could someone shed some light on these please? i.e. what the format for these properties is, how to add multiple columns, columns of different types etc..

Mark

 

Can anyone shed some light on this for me?

I could really use an example of this, as the API doesnt really give me much help on what the "Properties" or their format are for creating some columns. Also is this the right thing to be using when binding to columns that will not exist until a query join will return data? It seems to be, but i have not been able to get it to work.

 A better way to clarify this is in pseudo code.. (my join is massive and will just look complex here)

1    BusinessObjects.tblMyTableCollection Collection1 = new BusinessObjects.tblMyTableCollection();
2    BusinessObjects.tblMyTable2Collection Collection2 = new BusinessObjects.tblMyTable2Collection();
3    BusinessObjects.tblMyTableQuery Query1 = new BusinessObjects.tblMyTableQuery();
5    BusinessObjects.tblMyTable2Query Query2 = new BusinessObjects.tblMyTable2Query();
6    
7    Query1.Select(Query1.Field1, Query2.Field2, Query1.Field3);
8    Query1.InnerJoin(Query2).On(Query1.FK == Query2.PK);
9    Query1.Where(Query1.Field1 == "abcdef");
10   Query1.OrderBy(Query1.Field1.Ascending);
11   
12   Collection1.load(Query1);
13   
14   myList.BindingContext = new BindingContext();
15   myList.DataSource = Collection1;
16   myList.Refresh();

If the above code is run, and 0 rows are returned, the joined column "Field2" does not exist in the collection. If I run the query again and return a row.. the "Field2" still doesnt appear to be in the collection and the field in the list is blank.

 HOWEVER... if I exit the form altogether and then come back in and the 1st time the query is run it returns a row, everything works fine.
 

I just want a way to add the columns so that when I return 0 rows, THEN i return a row all the data will show up

Cheers,

Mark 

To help us duplicate this, you mentioned CF earlier. Is this a Device Application? What kind of control is myList?

Yes this is on the compact framework using SQL server CE, it is a WM5 Smart Device Application. MyList in this instance is a Resco Controlls Advanced List.

Mike - From what I can see, the issue is that if a collection is created using "BusinessObjects.tblCollection myCollection = new BusinessObjects.tblCollection ()" then populated with a join query with rows returned, the extra columns are added to the collection. If there are no rows returned, the extra columns are not added later, and thus the display can not bind to them. From what I can see, the columns need to be created on the 1st population of the collection or they do not appear.

Mike,
Could I not use the method mentioned above ("CreateColumnsForBinding") to create the few extra columns though? Or is there a way or re-creating the datatables/collection?

Mark

 

Mike,

How do I access the protected property? I can't seem to create a collection within a Private method, so I can't think of a sensible way to create a new collection, without possibly having a large number of them floating around, and then having to load the query onto lots of different collections.

Could I not manually add the columns using

EntitySpaces.Interfaces.esColumnMetadata myCol = new EntitySpaces.Interfaces.esColumnMetadata("name", enum, "String");

this.tblDefectCollection1.es.Meta.Columns.Add(myCol);

 If so is that the right format?

Mark
 

mike, I can't seem to find the "Table" property anywhere when doing an override.

Mark