14.4.4.Application Code

Most VSPX controls will support XML children specifying SQL code to run at various points of the page processing cycle. The elements are:


These elements will have a script tag as unique child, most often containing a CDATA section for escaping the SQL text.

Additionally, most attributes of VSPX elements can have a SQL expression evaluated at initialization, pre data bind or after data bind time, as the case may be, depending on the attribute and its value. An attribute value beginning with "--" indicates evaluation on the initialization or the descending edge of the data bind pass. An attribute value indicating "--after" specifies that the value is calculated on the returning edge of recursion of the data bind pass.

Arbitrary HTML text may contain attributes with a data bound value. The attributes should be in the XHTML namespace and have a text beginning with "--" . The expression will be evaluated at render time, where the control variable refers to the enclosing VSPX template control, e.g. the page instance when at top level.

VSP Compatibility and In-Line SQL

Arbitrary HTML text may contain <?vsp ?>, <?V ?> (equivalent of <?= VSP notation) and <?U ?> (equivalent of <?/ VSP notation) processing instructions. The code in question will be evaluated during the render pass, with control set to the closest enclosing VSPX control. Please note that the <?= and <?/ VSP shortcuts cannot be used inside VSPX pages as they are not valid processing-instructions.

VSPX maintains backward compatibility with VSP through supporting the same processing instructions, but additionally requires the page source to be well formed XML. VSP pages which are well formed in XML terms will run as such under with the VSPX extension, with the addition of the v:page top level element.

The <?vsp ?> processing instruction expects a SQL statement. The statement can be a compound statement ending in another <?vsp ?> processing instruction at the same nesting level under the same parent tag. The other pi's <?V and <?U expect a SQL expression.

[Note] Note:

<?V ?> is not permitted inside attributes without quotation, as this is not well formed XML. When quoted, this notation in attributes has no special effect, hence the convention about the leading "--" and the XHTML namespace for HTML attributes with a computed value.