XForms, Binding in Repeats

Motivation

You have a list of items and you want a simple way of conditionally displaying fields within a repeated group.

Method

We will do this is two ways. First we will use a bind expression in the model. The second method of doing this will be to use a group element with a ref attribute.

Sample Data

xmlns="">

yes
display 1

no
display 2

yes
display 3

Sample Repeat

nodeset="instance('my-data')/group" id="my-repeat">

Group # value="count(preceding-sibling::*) +1">

ref="code">
Display Input Field:

Yes
yes

No
no

ref="field" >
Conditional Display:

Solution Using Relative Binds

In this example we use a relative statement to indicate that the field should only be displayed if the code value is "yes". Note that the context of the relevant expression is the result of each nodeset item.

id="field"
nodeset="instance('my-data')/group/field"
relevant="../code = 'yes'"/>

Solution Using Group Element

We can use the ref attribute to conditionally display any field within a repeat. We do this by starting the group ref attribute with "." to give it the current context. Then we add a predicate to turn on or off that entire group. In this case if the code is "yes" the input field will be displayed. If it is not the field will be hidden.

ref=".[code='yes']">
ref="field">
Conditional Display:

Complete Example

xmlns="http://www.w3.org/1999/xhtml"
xmlns:xf="http://www.w3.org/2002/xforms">;

Binds in Repeats
type="text/css">
@namespace xf url("http://www.w3.org/2002/xforms");
body {{
font-family:Helvetica, sans-serif;
}}

id="my-data">
xmlns="">

yes
display 1

no
display 2

yes
display 3

no
display 4

id="field"
nodeset="instance('my-data')/group/field"
relevant="../code = 'yes'"/>

Test of binding rules within a repeat
nodeset="instance('my-data')/group" id="my-repeat">

Group # value="count(preceding-sibling::*) +1">

ref="code">
Display Input Field:

Yes
yes

No
no

ref="field" >
Conditional Display:

value="index('my-repeat')">
Current Selected Group:

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