SharePoint: Extending the DVWP – Part 9: Oops! Failed Setting Processor Stylesheet

Author: Jim Bob Howard

If you’ve tried to add workflow to Dataview Web Part (DVWP) form action links using Form Fields (or if you were following along on the last article), you probably saw this error when you went back to the Design pane:

Failed setting processor stylesheet

Notice it says, A reference to variable or parameter ‘Pos’ cannot be resolved. The variable or parameter may not be defined, or it may not be in scope. It’s true, this parameter is not in scope out-of-the-box, because it’s not passed into this specific template which is used to draw the save and cancel buttons.

1. In the Code pane, search for :template name="dvt_1.automode":

<xsl:template name="dvt_1.automode">
        <xsl:param name="KeyField" />
        <xsl:param name="KeyValue" />
        <xsl:param name="Mode" />
       . . .

2. So, let’s get it in scope. The first thing will be to add it to the list of xsl:param calls on this template:

<xsl:template name="dvt_1.automode">
        <xsl:param name="KeyField" />
        <xsl:param name="KeyValue" />
        <xsl:param name="Mode" />
        <xsl:param name="Pos" />
       . . .

Easy enough. But…

3. If calls to this template don’t include xsl:with-param for Pos, we’re still going to have trouble. That means every call to this template must pass Pos along, if you add a workflow that accesses the form fields.

When I search my webpart, there are three calls to <xsl:call-template name="dvt_1.automode">, one for each of the display templates: default, edit, and insert;so each of those will need to have something passed along through Pos. For the most part, we simply want to pass along the variable already defined by the template calling this one:  <xsl:with-param name="Pos" select="$Pos"/>, which basically takes the current value of Pos that is in scope and passes it down into this one.

<xsl:call-template name="dvt_1.automode">
        <xsl:with-param name="KeyField">ID</xsl:with-param>
        <xsl:with-param name="KeyValue" select="ddwrt:EscapeDelims(string(@ID))" />
        <xsl:with-param name="Mode">edit</xsl:with-param>
        <xsl:with-param name="Pos" select="$Pos"/> // simply insert this line to pass the $Pos value down
</xsl:call-template>

4. One more issue: The dvt_1.rowview template calls the dvt_1.automode, but doesn’t have $Pos in scope. So, we’ll need to pass it into that template so it can pass it on to the next one.

1. Search for :template name="dvt_1.body"

<xsl:template name="dvt_1.body">
        <xsl:param name="Rows"/>
        <xsl:for-each select="$Rows">
                <xsl:choose>
                        <xsl:when test="$dvt_1_form_editkey = ddwrt:EscapeDelims(string(@ID))">
                                <xsl:call-template name="dvt_1.rowedit">
                                        <xsl:with-param name="Pos" select="concat('_', position())" />
                                </xsl:call-template>
                        </xsl:when>
                        <xsl:otherwise>
                                <xsl:call-template name="dvt_1.rowview" />
                        </xsl:otherwise>
                </xsl:choose>
        </xsl:for-each>
</xsl:template>

This block is the entire template for the body of the form. It will either draw the edit view, or it will draw standard row view. Look at line 2032 above.

2. This is known as an empty tag, meaning it opens and closes all in one tag. To "open" the tag, we’ll need to remove the / from the end of line 2032 and add the closing tag </xsl:call-template> after the tag. Then we can add the with-param tag, like in the template call to dvt_1.rowedit:

<xsl:otherwise>
        <xsl:call-template name="dvt_1.rowview">
                <xsl:with-param name="Pos" select="concat('_', position())" />
        </xsl:call-template>
</xsl:otherwise>

3. Just below this code, you will most likely find the template definition for dvt_1.rowview (if not, search for :template name="dvt_1.rowview"). We now need to add the $Pos parameter to this template so it can receive the with-param value we just added to the call-template.

<xsl:template name="dvt_1.rowview">
        <xsl:param name="Pos"/>
        . . .

You can now call a workflow from your DVWP and access the content the user just entered or edited.

Yes, this is squarely advanced XSLT editing. Need help? See Marc Anderson’s excellent EUSP series Unlocking the Mysteries of Data View Web Part XSL Tags.

Next time: Wouldn’t it be great if you could pass a variable to your workflow, too? You can. I’ll cover that in the next installment of Extending the DVWP.

Author: Jim Bob Howard

Jim Bob Howard is a web designer / webmaster in the healthcare industry. He has been working with SharePoint since March 2009 and enjoys sharing what he has learned. He is a moderator and frequent contributor to Stump the Panel, and answers SharePoint questions on Twitter (@jbhoward) and via email ([email protected]).