How to get List from Visualforce Component Controller

Question

I have a visualforce component which is used in an email template to display a list of related items.

Visualforce Component

<apex:component controller="LeadProductsController" access="global">

    <apex:attribute name="parentId" type="Id" assignTo="{!leadId}" description="" />
    <apex:attribute name="products" type="Lead_Product__c[]" description="" />

    <table style="width:500px" cellpadding="3" cellspacing="0" border="0">
        <thead style="background-color: #003366; color: #ffffff;">
            <td>Name</td>
            <td>Code</td>
            <td>QTY</td>
            <td>Sales Price</td>
            <td>Total Price</td>
        </thead>
        <tbody>
            <apex:repeat value="{!products}" var="p">
                <tr>
                    <td>{!p.Product_Name__c}</td>
                    <td>{!p.Product_Code__c }</td>
                    <td>{!p.Quantity__c}</td>
                    <td>0</td>
                    <td>0</td>
                </tr>
            </apex:repeat>
        </tbody>
    </table>

</apex:component>

Apex Controller

public without sharing class LeadProductsController {

    public List<Lead_Product__c> products { get; private set; }

    public String leadId;

    public void setLeadId(Id leadId) {
        this.leadId = leadId;
        products = [SELECT Id, Product_Name__c, Product_Code__c, Quantity__c FROM Lead_Product__c WHERE Lead__c = :leadId];
    }

    public Id getLeadId() {
        return leadId;
    } 
}

I then use the component in the email template like this:

<c:LeadProducts parentId="{!relatedTo.Id}" ></c:LeadProducts>

I've not used visualforce component's before, so I suspect I am doing many things wrong, but I cannot find a decent example of what I am trying to achieve.

How should I get a List of data from a controller when using a visualforce component?

Answer 1

You have three glaring problems which don't have anything to do with the error:

1. Your attribute name and assignTo use the same name.
   • You have to use different values, or you should get a compile fail.
   • See also: How to solve the apex:attribute and assignTo naming conflict?
2. Your query selects only Id.
   • Make sure you actually pull all the fields you need.
3. You make your query in your constructor.
   • Data retrieval needs to move to your leadId setter.
   • The constructor fires before this setter and as currently written will use null as the filter value.

Now for the actual cause:

1. Your products Apex variable is not an attribute.

   • Add { get; private set; } to the end of the line:

     public List<Lead_Product__c> products { get; private set; }
     

   • Always use a private setter unless you actually want the page to write to this variable.

2. You have included products as a conflicting <apex:attribute>.

   • Simply remove this line from your markup:

     <apex:attribute name="products" type="List" description="" />
     

   • You set the type as List, which I assume implicitly converts to Object[].
   • If you needed this <apex:attribute>, you would change the type to Lead_Product__c[]