[SalesForce] How to call parametrized function from Visualforce

I have a parametrized helper function in my controller, which formats text according to requirements.

public static string getFormatMe(string a) {
    // do manipulation here
    return a;
}

How do I call this from Visualforce, to format my data?

This does not work:

<apex:outputText value="{!formatMe('test')}" />

Save error: Unknown function formatMe. Check spelling.

Here is a solution to a similar question, but that is for calling a function without parameters: How can I call a method from visualforce?

Best Answer

You cannot pass parameters to method bindings made in your Visualforce page to your controller, as per the help topic here, you can only provide 'action', 'get' and 'set' methods.

In order to implement your requirement I would recommend you consider looking at Visualforce Components, such that you can have something like

 <c:myOutputText myValue="test"/>
 <c:myOutputText myValue="{!MyObject__c.MyFieldToFormat__c}"/>

This component would internally use the apex:outputText component as above, however its controller would have been passed the 'test' value as an attribute to the component. On the controller you would have a getFormattedValue to output the formatted version.

<apex:component controller="MyOutputTextController">
  <apex:attribute name="myValue" type="String" description="Value to format" assignTo="{!myValueAttr}"/>
  <apex:outputText value="{!formattedValue}"/>
</apex:component>

Related Solutions

[SalesForce] Rendering a Conditional Format for VisualForce Table Cell

Visualforce's expression language doesn't support the calling of controller methods with arbitrary parameters. (In occasional circumstances you may be able to use the available map syntax to approximate this.)

The binding between Visualforce pages and controllers is primarily based on controller properties that at most can have setter and getter methods. Multiple levels of reference are supported though e.g. "Child.Parent.ParentField".

So unfortunately you have to bend your thinking to these limitations, and as @dphil suggests that generally means refactoring so that instead of your controller supplying a list of SObjects, it supplies a list of "wrapper" objects:

public class MyWrapper {
    public MySObject__c sob {get; private set;}
    public MyWrapper(MySObject__c sob) {
        this.sob = sob;
    }
    public String getStyle() {
        Decimal val = getDefendNTAPNum();
        if (val >= 0 && val < 25) {
            return 'background-color:#FF0000;';
        } else if ...
    }
    public Decimal getDefendNTAPNum() {
        return ...;
    }
}

Then your page can reference a "computed" value or just the underlying SObject field as required:

<apex:column headervalue="SitNum" style="{!w.style}" value="{!w.sob.MyField__c}">

Note that there is also a set of built in functions (including a CASE function) that sometimes can be used to implement basic conditional logic within the Visualforce expression.

[SalesForce] Unable to call a static method in expression in visualforce page

Unfortunately (and perhaps surprisingly) you can't in a Visualforce expression.

See this answer Rendering a Conditional Format for VisualForce Table Cell for the normal work-around of using a wrapper class.

Best Answer

Related Solutions

[SalesForce] Rendering a Conditional Format for VisualForce Table Cell

[SalesForce] Unable to call a static method in expression in visualforce page

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