Question

I’m trying to create a custom component that when instantiated in form builder it would have in fr-form-instance a node containing child nodes and not only a single node as shown in the tutorial:
http://wiki.orbeon.com/forms/doc/developer-guide/xbl-components-guide#TOC-Event-handling.

For example if I instantiate the tutorial input component in form-builder :

.....

    <fb:metadata>
        <fb:display-name lang="en">Custom Component</fb:display-name>
        <fb:datatype>xforms:string</fb:datatype>
        <fb:template>
            <cc:test ref=""/>
        </fb:template>
    </fb:metadata>   
    <xbl:binding element="fr|tutorial-input" id="fr-tutorial-input">
        <xbl:template>
            <xforms:group xbl:attr="model context ref bind" xxbl:scope="outer">
                <xbl:content includes="xforms|label,xforms|help,xforms|hint,xforms|alert"/>
                <xforms:group xxbl:scope="inner">
                    <xxforms:variable name="binding" as="node()?">
                        <xxforms:sequence select="." xxbl:scope="outer"/>
                    </xxforms:variable>
                    <xforms:input ref="$binding"/>
                </xforms:group>
            </xforms:group>
        </xbl:template>
    </xbl:binding>

..... 

Form builder will only have one node in fr-form-instance:

.....
    <xforms:instance id="fr-form-instance">
        <form>
            <section>
                <contorl-x/> //only one node
.....

What I would like to do is have:

.....
    <xforms:instance id="fr-form-instance">
        <form>
            <section>
                <contorl-x>// x child nodes 
                    <contorl-x-child-one> 
                    <contorl-x-child-two> 
                       .....
                </contorl-x> 
.....

Is it possible to do this? Are there in other components/examples that behave similar to this?

Answer 1

Section templates do something similar:

• when you insert a section template, Form Builder only inserts one element
• the section template component, at runtime, when becoming visible, inserts its nested elements

You can see how this is done in form-to-xbl.xsl.

Similarly, here is a prototype for an XBL component creating an element if missing.

Now the devil is in the details. You have to determine in particular:

• when the component creates its nested elements
• whether it ever deletes them

Also, one thing to keep in mind is that the XBL component itself cannot, at this time, validate nested elements. Only the top-level elements, with binds generated by Form Builder, can validate the data.

Section templates work around this by validating a sub-instance within the XBL component itself.