Basic syntax for DataWindow property expressions in PowerBuilder
Description
DataWindow property expressions in PowerBuilder use dot notation
to specify the controls and properties that you want to access.
Syntax
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<span>dwcontrol</span>.<span>Object</span>.<span>dwcontrolname</span> { .<span></span><span>property</span> } .<span>property</span><span></span> { = value } |
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Argument |
Description |
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dwcontrol |
The name of the DataWindow control or |
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Object |
Object indicates that subsequent elements |
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dwcontrolname |
a control within the DataWindow object.  Nested DataWindow objects
If dwcontrolname is a column with the For nested syntax, see “Syntax for nested objects |
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property |
A property that applies to dwcontrolname. For lists of applicable properties, see the |
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value |
A string whose value is to be assigned If the property value is a number, value can If the property value is a yes or no value, value can If the property value can be an expression, then value can
where:
For examples of DataWindow expressions, see “Using DataWindow expressions |
Datatype
Any. The datatype of the expression is Any, but actual data
is a string.
For more information about the expression’s
datatype, see “Datatypes of DataWindow
property expressions in PowerBuilder”.
Examples
Example 1 Boolean property values In
this statement, the boolean value false is stored as the string
“no”:
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dw_1.Object.DataWindow.ReadOnly = false |
This statement displays the value of the ReadOnly property
(either “yes” or “no”) in the StaticText st_status:
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st_status.Text = dw_1.Object.DataWindow.ReadOnly |
When you test the value of a property in a relational expression,
you must compare your test value to the stored values. For ReadOnly,
stored values are yes or no, not boolean true or false:
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IF dw_1.Object.DataWindow.Readonly = 'yes' THEN |
This statement fails because the expression is not boolean:
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IF dw_1.Object.DataWindow.Readonly THEN // Not valid |
Example 2 Valid values for the
Visible property are 0 and 1. You can set the property to numbers,
yes and no, or true and false.
Therefore, these three statements are equivalent:
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dw_1.Object.street.Visible = false |
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dw_1.Object.street.Visible = "NO" |
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dw_1.Object.street.Visible = 0 |
Example 3 This example tests
whether the X property contains a constant (which can be converted
to a number) or a DataWindow expression. The code assigns a default
value of 50 to the variable li_x, which remains the value
if the property contains an expression the script cannot convert:
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integer li_x |
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IF IsNumber( dw_1.Object.id.X ) THEN |
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li_x = Integer( dw_1.Object.id.X ) |
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ELSE |
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li_x = 50 |
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END IF |
Example 4 This script sets the
X property to a DataWindow expression. The expression causes IDs
with values less than 10 to be indented:
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string modstring, ls_x |
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ls_x = "50" |
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modstring = ls_x + "~t" + & |
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"If(id > 10, " + ls_x + "," + & |
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String(li_x + 20 ) + ")" |
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dw_1.Object.id.X = modstring |
Example 5 This example makes
three columns updatable and reports the value of the Update property
in the StaticText st_status. The reported value is “yes,” not true:
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dw_1.Object.id.Update = true |
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dw_1.Object.street.Update = true |
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dw_1.Object.last_name.Update = true |
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st_status.Text = & |
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"Updateable: id " + dw_1.Object.id.Update + & |
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", street " + dw_1.Object.street.Update + & |
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", last_name " + dw_1.Object.last_name.Update |
Example 6 This example checks
whether the id column is set up as a spin control. If so, it sets
the spin range to 0 through 10:
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IF dw_1.Object.id.EditMask.Spin = "yes" THEN |
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dw_1.Object.id.EditMask.SpinRange = "0~~~~10" |
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END IF |