Class: cDbCJGridColumn

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Models a data aware grid column within a cDbCJGrid object



Library: Windows Application Class Library

Package: cdbCJGridColumn.pkg


The cDbCJGridColumn class is used to provide columns for data-aware cDbCJGrid objects.
Every column in a grid is represented by a grid column object. Regular cCJGrid objects use a cCJGridColumn object for each column, while data-aware cDbCJGrid objects use a cDbCJGridColumn.

You should review the cCJGridColumn documentation for a description of the general purpose of a grid column object. This subclass extends those capabilities. The main extensions are:

- The column object is bound to a table.column with the Entry_Item command, which sets the piBindingTable and piBindingColumn properties. This binding is used to:

- Based on the table binding information, it uses the DataDictionary to provide a number of services. This includes:

In addition, it inherits these features from the cCJGridColumn class:

A data-aware grid will normally consist of a single cDbCJGrid object, an internally created cDbCJGridDataSource object and multiple cDbCJGridColumn objects to define the grid. With data-aware grid columns, the table binding data provides the information to set up the column. This makes the grid column object code simple. The data is loaded and ordered based on the grid's Server and Ordering properties

Object oOrderDtl_Grid is a cDbCJGrid
    Set Server to OrderDtl_DD
    Set Ordering to 1
    Set Size to 63 377
    Set Location to 90 3
    Set peAnchors to anAll
    Set pbAllowInsertRow to False
    Set pbRestoreLayout to True
    Set psLayoutSection to "OrderView_oOrderDtl_Grid1"
    Set piLayoutBuild to 6
    Set pbHeaderPrompts to True
    Object oMark is a cCJGridColumnRowIndicator
    Object oInvt_Item_ID is a cDbCJGridColumn
        Entry_Item Invt.Item_ID
        Set piWidth to 91
        Set psCaption to "Item ID"
        Set psImage to "ActionPrompt.ico"

    Object oInvt_Description is a cDbCJGridColumn
        Entry_Item Invt.Description
        Set piWidth to 213
        Set psCaption to "Description"

    Object oInvt_Unit_Price is a cDbCJGridColumn
        Entry_Item Invt.Unit_Price
        Set piWidth to 53
        Set psCaption to "Unit Price"

    Object oOrderDtl_Qty_Ordered is a cDbCJGridColumn
        Entry_Item OrderDtl.Qty_Ordered
        Set piWidth to 50
        Set psCaption to "Quantity"

    Object oOrderDtl_Price is a cDbCJGridColumn
        Entry_Item OrderDtl.Price
        Set piWidth to 62
        Set psCaption to "Price"

    Object oOrderDtl_Extended_Price is a cDbCJGridColumn
        Entry_Item OrderDtl.Extended_Price
        Set piWidth to 81
        Set psCaption to "Total"

In the above example, the cCJGridColumnRowIndicator is a non-data-aware subclass of the cCJGridColumn class. You will usually not mix regular and data-aware grid classes in a cDbCJGrid class, but it is allowed. However, you may not place a cDbCJGridColumn class inside of a non-data-aware cCJGrid class.


Data-aware grid columns augment the InitialValue function to load data from your table buffers into your datasource. InitialValue uses table binding properties, piBindingTable and piBindingColumn (which are set with the Entry_Item command) to move the table data into the datasource.

If you do not set any binding table information (i.e., no Entry_Item command), this column is considered to be a calculated column. In this case, when InitialValue is called, it calls the OnSetCalculatedValue event. You can use this event to create a calculated value for the cell.

Object oOrderDtl_Tax is a cDbCJGridColumn
    Set piWidth to 81
    Set psCaption to "Tax"
    Set pbFocusable to False

    Procedure OnSetCalculatedValue String ByRef sValue
        Number nTaxRate
        Get TaxRate to nTaxRate
        Move (OrderDtl.Extended_Price * nTaxRate) to sValue

Because the calculation is handled in code, you can make the calculation as complex as needed, including the use of conditional code..

Procedure OnSetCalculatedValue String ByRef sValue
    String sTaxable
    Number nTaxRate

    Get TaxRate to nTaxRate
    Get SelectedRowValue of oOrderDtl_Taxable to sTaxable
    If (sTaxable="Y") Begin
        Move (OrderDtl.Extended_Price * nTaxRate) to sValue
    Else Begin
        Move 0 to sValue