massAttribute for multiple attribute-value pairs

[VsevolodGolovanov]

Like in #10, I have a bunch of inputs, but they have multiple common attribute values. With the current o:massAttribute implementation setting them is quite ugly:

<o:massAttribute name="value" value="#{filter.value}" target="javax.faces.component.UIInput">
    <o:massAttribute name="required" value="#{filter.required}" target="javax.faces.component.UIInput">
        <o:massAttribute name="disabled" value="#{filter.readOnly}" target="javax.faces.component.UIInput">
            <...>
                <x:inputThis />
                <y:inputThat />
            </...>
        </o:massAttribute>
    </o:massAttribute>
</o:massAttribute>

The nesting seems superfluous, the target is duplicated. Instead there could be something like:

<o:massAttributes target="javax.faces.component.UIInput">
    <o:pair key="value" value="#{filter.value}" />
    <o:pair key="required" value="#{filter.required}" />
    <o:pair key="disabled" value="#{filter.readOnly}" />

    <...>
        <x:inputThis />
        <y:inputThat />
    </...>
</o:massAttributes>

Couldn't reuse f:attributes here, since massAttribute has no component. Maybe create a custom tag for passing attributes to tag handlers, but there is already o:tagAttribute, so that could be confusing.

[BalusC]

Makes sense.

[arjantijms]

Key/values can also be set using the map literal syntax from EL, if we accept Map as type.

[BalusC]

It only requires EL 3.0.

[BalusC]

As we're now on OmniFaces 3.0 which supports EL 3.0, I took a second look. Unfortunately, the map idea didn't work out very well. EL 3.0 API doesn't offer any way to break down the map values into fullworthy ValueExpression instances. Instead, it immediately evaluates those value expressions while <o:massAttribute> needs to set the ValueExpression in its original and unevaluated form into the component. Otherwise, this won't work for dynamic and writable properties.

[BalusC]

Closing off because it's technically not possible.