[SalesForce] How to solve the apex:attribute and assignTo naming conflict

So consider a component with an attribute like this:

<apex:attribute name="rentalContract" type="RentalContract__c" assignTo="{!rentalContract}"/>

And this is how my controller looks like:

public with sharing class RentalContractController {
    public RentalContract__c rentalContract { get; set; }
}

As you all may probably know this will not work anymore with API >= 27 because in Spring '13 they introduced Compile-Time Checking for Custom Component Attribute Names which basically means that the name for your attribute cannot be the same name that you assign to.

The release notes further state:

To make this component compile under API version 27.0, change either the attribute name or the assignTo value (which might require you to also change a controller method or property).

So this is all nice and dandy – but how do you really solve it? Because if I do make a custom controller I likely name its main variable after its object. Plus it's similar to standard controllers where you can just use the object name as the variable – so it's very similar to this.

On the other hand – when I do make a component I likely name the variables after the objects they use. Which works fine until I want to wire this up with a controller which is using the same name. And then I end up renaming one or the other – which might or might not work so good in a managed package, plus it can involve a lot of renaming and unnecessary code changes.

So my question is: Is there some kind of pattern, idiom, whatever … that you've come up with that prevents events like this? I would tend to always name the attribute in the component not exactly after the object because I think that is easier to change – but in what way? Because options like myRentalContract or theRentalContract clearly show that this is purely a technical fix plus it isn't really obvious to the developer using it. So imho that is a bad solution to an unnecessary problem.

I've run into this problem so many times that I really want a good solution for this so I don't have to think about naming these things so much – because as you all may remember – naming things is the hardest and it takes a lot of time. In this case it takes way too much time.

Best Answer

Using generic terms on one side or the other can help. So instead of rentalContract, use record (single instance of an SObject) or, instead of rentalContractId, use recordId. Even these two alone give you a lot more flexibility.

In general, I would try to put the more generic names as the outward facing attributes.

Component

<apex:component controller="MyController">
    <apex:attribute type="Id" name="recordId" assignTo="{!myObjectId}" />
</apex:component>

Controller

public with sharing class MyController
{
    public Id myObjectId { get; set; }
}

In this way, your references to custom built components will be more consistent.

<c:customComponent1 recordId="{!someId}" />
<c:customComponent2 record="{!someRecord}" />

Related Solutions

[SalesForce] Spring ’13 VF Component Issue

From the spring 13 release notes

there is a new compile-time check that prevents giving custom Visualforce component attributes the same name as the assignTovalue (which can refer to a property or method in the component’s controller). This checking prevents a number of programming errors (bugs) that can result in runtime errors. This change is versioned, and you must update your Visualforcecomponents and the pages that contain them to API version 27.0 to enable the new behavior.

To make this component compile under API version 27.0, change either the attribute name or the assignTovalue (which might require you to also change a controller method or property).

[SalesForce] Does the assignTo attribute of apex:attribute not work for ApexPages.Action or PageReference types

One mechanism for doing this would be to pass the page controller instance as the parameter to the component and then the component can call the page controller's methods itself via that reference.

Here is a functional example:

Page Controller

public with sharing class TestPageController {

    public TestPageController selfReference { get; set; }

    public Integer myInteger { get; set; }
    public String myString { get; set; }

    public TestPageController() {
        this.myInteger = 1;
        this.myString = String.valueOf(this.myInteger);
        selfReference = this;
    }

    public PageReference myStringAction() {
        // increment the integer and add it to the string
        this.myInteger += 1;
        this.myString += ', ' + String.valueOf(this.myInteger);
        return null;
    }
    public PageReference myRedirectAction() {
        // this essentially is doing a 'reset'
        PageReference pRef = Page.TestPage;
        pRef.setRedirect(true);
        return pRef;
    }
}

Component Controller

public with sharing class TestComponentController {

    public TestPageController thePageController { get; set; }

    public PageReference doPageControllerAction1() {
        return thePageController.myStringAction();
    }

    public PageReference doPageControllerAction2() {
        return thePageController.myRedirectAction();
    }
}

Component Markup (TestComponent.component)

<apex:component controller="TestComponentController" >
    <apex:attribute name="PageController" type="TestPageController" assignTo="{!thePageController}" required="true" description="the root page controller reference" />

    <p>The Component Body</p>
    <p>via local component controller methods by reference</p>
    <apex:commandButton action="{!doPageControllerAction1}" value="Fire Page Controller Action 1 (string) through component controller method" /><br />
    <apex:commandButton action="{!doPageControllerAction2}" value="Fire Page Controller Action 2 (redirect) through component controller method"/><br />

    <p>via Component Attribute's Name property reference</p>
    <apex:commandButton action="{!PageController.myStringAction}" value="Fire string action method through attribute name reference" /><br />

    <p>via direct reference through value set by 'assignTo' on attribute</p> 
    <apex:commandButton action="{!thePageController.myStringACtion}" value="Fire string action through controller reference" /><br />

    <p>data retrieved via component controller's pagecontroller reference</p>

    MyInteger: <apex:outputText value="{!thePageController.myInteger}" /><br />
    MyString: <apex:outputText value="{!thePageController.myString}" /><br />
</apex:component>

Page Markup (TestPage.page)

<apex:page controller="TestPageController" >
    <p>the myString value will be concatenated each time an action fires with the current myInteger value</p>
    <apex:form> 
        <c:TestComponent PageController="{!selfReference}" />
    </apex:form>
</apex:page>

Best Answer

Related Solutions

[SalesForce] Spring ’13 VF Component Issue

[SalesForce] Does the assignTo attribute of apex:attribute not work for ApexPages.Action or PageReference types

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