Getting the Column Name using ColToFieldIndex

[Erlly Bayuelo]

In our application grid,we have a "View" collection in which the user specifies which columns and in which order to show them on the grid.
Therefore, we are only adding the columns of the underlying datasource that we want to view using the GridColumnDescriptor collection Add() method. As a result, our Fields collection and our Columns collection are not in the same order and do not have the same number of items.

Now when we are in grid_TableControlPrepareViewStyleInfo() or grid_QueryCellStyleInfo() we are trying to get the name of the column of the current cell. We have been using:
this.grid.TableDescriptor.Columns[this.grid.TableModel.ColIndexToField(e.Inner.ColIndex)].Name

and
e.TableCellIdentity.Table.TableDescriptor.Columns[grid.Table.TableModel.ColIndexToField(e.TableCellIdentity.ColIndex)].Name

respectively.
However, I want to make sure that I am doing this correctly since the ColIndexToField naming convention seems to imply that I have to use this to get items from the Fields collection and I am using it to get an item from the columns collection. It seems to be working at the moment and ironically when I use it against the fields collection it does not work properly [I think it is because my Fields collection does not match my Columns collection]

[Administrator]

Hi Erly,

your method calls should be fine as long as you don''t have column sets and as long as you did not modifiy the VisibleColumns collection.

Better is to use the information that is already provided to you through GridTableCellStyleInfoIdentity.

Example:

GridTableCellStyleInfo style = e.TableControl.Model[e.Inner.RowIndex, e.Inner.ColIndex];
GridTableCellStyleInfoIdentity id = style.TableCellIdentity;
GridColumnDescriptor column = id.Column;

Stefan

[Erlly Bayuelo]

Hi Stefan,
Thanks for the info. The code that you sent me works fine for Record Element types but not for Caption Rows (i.e. id.Column is undefined) that is why I was using the code I originally listed which works for both. We have CaptionSummaryRows and sometimes we want to get column names when we transverse those too.
I have now since modified my code to use your code for RecordFieldCell and AlternateRecordFieldCell. However I have left my code whenever TableCellIdentity.DisplayElement is CaptionRow.
So, to answer my original question does ColToFieldIndex() return the index of the Fields collection or the Columns collection? In my code I am using it to successfully to query the columns collection.

[Administrator]

Hi Erlly,

it is correct only if you have not modified the VisibleColumns collection.

Better is the TableDescriptor.GetHeaderColumnDescriptorAt instead. Then you are on the safe side. Its implementation looks as follows

		public GridColumnDescriptor GetHeaderColumnDescriptorAt(int colIndex)
		{
			GridColumnDescriptor[,] recordRowColumns = TableDescriptor.RecordRowColumns;
			int fieldNum = TableDescriptor.ColIndexToField(colIndex);
			return recordRowColumns[0, fieldNum];
		}

Use it this way:

GridColumnDescriptor column = 
e.TableCellIdentity.Table.TableDescriptor.GetHeaderColumnDescriptorAt(e.TableCellIdentity.ColIndex)


Stefan
            

[Administrator]

Correction:

GridTable table = style.TableCellIdentity.Table;
GridColumnDescriptor column = table.GetHeaderColumnDescriptorAt(style.TableCellIdentity.ColIndex);

It is a member of GridTable.

Stefan