Same Date, self reference? Work-around ideas

Question

I have got a lot of research and recherche done as this simple where clause doesn't work because of it self-reference.

I want to display all leads and opportunities who have the same "datefield x" as the actually shown lead in a visual force standard list controller. Has anybody an idea how to solve this?

Kind regards. Constantin

VF-Page

<apex:page controller="c2" extensions="extension_current_lead">
  <apex:pageBlock title="Leads" >
  <apex:PageBlockTable value="{!acts}" var="a">
  <apex:column value="{!a.Name}"/>
  <apex:column value="{!a.Budget__c}"/>
  <apex:column value="{!a.Eventart__c}"/>
  <apex:column value="{!a.Gaestezahl__c}"/>
  </apex:PageBlockTable>
  <apex:PageBlockTable value="{!acts2}" var="a">
  <apex:column value="{!a.Name}"/>
  <apex:column value="{!a.Amount}"/>
  <apex:column value="{!a.EventArtC__c}"/>
  <apex:column value="{!a.AnzahlDerGaeste_C__c}"/>
  </apex:PageBlockTable>

apex class

public class c2{

List<Lead> currentLeads = [SELECT DatumEvent__c FROM Lead WHERE Id = :currentId];

if (!currentLeads.isEmpty()) {
Date currentDate = currentLeads[0].DatumEvent__c;

List<Lead> acts = [SELECT Id, Name, Budget__c, Eventart__c, Gaestezahl__c FROM Lead WHERE DatumEvent__c = :currentDate];
List<Opportunity> acts2 = [SELECT Name, Amount, EventArtC__c, AnzahlDerGaeste_C__c FROM Opportunity WHERE DatumEvent__c = :currentDate];

public List<Lead> getacts(){
return acts;
}
public List<Opportunity> getacts2(){
return acts2;
}
}

Error: Kompilierungsfehler: Expecting '}' but was: 'if' in Zeile 5, Spalte 1

Update: I created an extension class as suggested.

public class extension_current_lead
{

public Lead lead{get;set;}
public extension_current_lead ()
{
    Id id=apexpages.curentPage().getParameters().get('ID');
    kead=[select Id, Name, Budget__c, Eventart__c, Gaestezahl__c from Lead where ID=:id];
    }
}   

Answer 1

As long as you have the ID for the currently displayed Lead, which you should be able to get from the standard controller passed to an extension controller, you can query its date then using this date query the Leads and Opportunities that have that same date.

List<Lead> currentLeads = [SELECT YourDate__c FROM Lead WHERE Id = :currentId];

if (!currentLeads.isEmpty()) {
    Date currentDate = currentLeads[0].YourDate__c;

    List<Lead> leads = [SELECT Id, ... FROM Lead WHERE YourDate__c = :currentDate];
    List<Opportunity> opps = [SELECT Name, ... FROM Opportunity WHERE YourDate__c = :currentDate];

    // Now process the leads and opportunities that matched in whatever way is required
}

If you have a page that starts something like:

<apex:page standardController="Lead" extensions="MyLeadExtension">
    ...

Then your MyLeadExtension can have a constructor that gets the current Lead ID:

public with sharing class MyLeadExtension {
    private Id currentId = null;

    public MyLeadExtension(ApexPages.StandardController controller) {
        currentId = controller.getRecord().Id;

        ...
    }

    ...
}