XBL Bindings

Introduction

An XBL file contains one or more bindings, expressed with the xbl:binding element:

<xbl:binding
  id="fr-number"
  element="fr|number, xf|input:xxf-type('xs:decimal')"
  xxbl:mode="lhha binding value focus">

The binding:

  • describes the component's markup and behavior
  • determines which XML elements, in the source form, it associates with

Binding selectors

Introduction

The element attribute specifies, via one or more CSS selectors, which XML elements, in the source form, it associates with. The following CSS selectors are supported:

  • by element name
  • by element name and XML datatype (Form Builder only)
  • by attribute only [SINCE Orbeon Forms 4.9]
  • by element name and attribute [SINCE Orbeon Forms 4.9]

Binding by element name

The simplest way is to bind by element name:

element="fr|number"

This means that elements called fr:number in the form will use this binding.

Binding by datatype

Form Builder, at design time only (as of Orbeon Forms 4.9), also supports bindings by name and XML datatype:

xf|input:xxf-type('xs:decimal')

This must be used on conjunction with a "direct" binding like fr|number:

fr|number, xf|input:xxf-type('xs:decimal')

In this case an input field (xf:input) bound to an xs:decimal or xf:decimal type will be substituted, at design time, with an fr:number binding.

NOTE: In the future, we would like such bindings to work at runtime as well, see #1248.

Binding by attribute

[SINCE Orbeon Forms 4.9]

It is possible to associate bindings by:

  • attribute only
  • or by name and attribute

The following matches elements such as <fr:character-counter> (by name) but also <foo:bar appearance="cool character-counter stuff">, because of the ~= operator which means that the attribute is "a list of whitespace-separated values, one of which is exactly equal to" character-counter:

element="fr|character-counter, [appearance ~= character-counter]"

The following matches elements having the character-counter appearance and which, at the same time, have the name foo:bar:

element="foo|bar[appearance ~= character-counter]"

The following standard CSS selector operations on attributes are supported: =, ~=, ^=, $=, *=, |= (from Selectors Level 4 draft):

Example Meaning
E[foo="bar"] an E element whose foo attribute value is exactly equal to bar
E[foo~="bar"] an E element whose foo attribute value is a list of whitespace-separated values, one of which is exactly equal to bar
E[foo^="bar"] an E element whose foo attribute value begins exactly with the string bar
E[foo$="bar"] an E element whose foo attribute value ends exactly with the string bar
E[foo*="bar"] an E element whose foo attribute value contains the substring bar
E[foo|="en"] an E element whose foo attribute value is a hyphen-separated list of values beginning with en

Binding to elements in the XForms namespace

[SINCE Orbeon Forms 4.10]

An XBL binding can also be bound to elements in the XForms namespace. For example:

fr|character-counter,
xf|input[appearance ~= character-counter],
xf|textarea[appearance ~= character-counter],
xf|secret[appearance ~= character-counter],
fr|tinymce[appearance ~= character-counter]

This selector associates, for example the following element to the fr:character-counter component:

<xf:input appearance="character-counter">

See also