VIsualForce Page which populates a Field

Question

I have an object called Sales_and_Marketing__c, and I would like to override the standard New button so that the field Sales_Contact__c (lookup to Contact) gets pre populated with the logged in User.

On the User object we have a field ContactId__c. This field is a of a data type of Text(18) and just holds the contact id.

I have looked on online for scenarios and have attempted to write this but i am a little confused and appreciate some help

Apex class :

public with sharing class NewMKtMaterialsRequest

{
    public Contact profileInfo {get;set;}
    public NewMKtMaterialsRequest(ApexPages.StandardController controller)
    //public NewMKtMaterialsRequest() 
{
        Id userId = UserInfo.getUserId();
        List<User> UserList = [select U.ContactId from User U where Id =: userId];
        Id contactId = UserList.get(0).ContactId;
//Contact profileInfo = [SELECT ID FROM Contact WHERE Id =: contactId LIMIT 1];

        Contact profileInfo = [SELECT 
            Id, 
            FirstName, 
            User__c, 
            User__r.Id, 
            User__r.Name 
        FROM Contact WHERE Id =: contactId LIMIT 1];

  }
public PageReference RedirectToMKTRequest()
    {
        return new PageReference('/a0R/e?Sales_Contact__c=contactId.id&nooverride=1');
  }
}

Visual Force Page ;

  <apex:page standardController="sales_and_marketing__c" extensions="NewMKtMaterialsRequest" action="{!RedirectToMKTRequest}">

        </apex:page>

Answer 1

You could create PageReference instance and put the parameters like this:

public PageReference RedirectToMKTRequest()
{
    PageReference pg = controller.edit();
    pg.getParameters().put('Sales_Contact__c', contactId);
    pg.getParameters().put('nooverride', '1');
    pg.setRedirect(true);
    return pg;
}

Answer 2

If I understand your issue correctly, I think I see the issue in here. The PageRef you're building:

return new PageReference('/a0R/e?Sales_Contact__c=contactId.id&nooverride=1');

You have the 'Sales_Contact__c=contactId.id' part, but it's inside quotes, meaning it will literally append the literal text 'contactId.id' in the URL.

Try this:

return new PageReference('/a0R/e?Sales_Contact__c=' + profileInfo.Id + '&nooverride=1');