Overriding Standard 'NEW' button using Visualforce or Creating custom button and replace standard button

Question

Using a Before trigger/ Workflow has not helped me fill in or provide a default value to a standard field(NAME) while saving a new record.

I was asked to build a Visual force page and then override the 'NEW' button to add a default value to the token field, type Name, which will then allow to save a record.

Visual force page code used to override 'NEW':

<apex:page standardController="Certification__c"
action="{!URLFOR($Action.Certification__c.New, NULL, ['Name'='DoNotEdit'], true)}"/>

My 'NEW' button before overriding:

My 'NEW' button after overriding.

My Contact look-up field value tends to disappear after i override the new button page. Token is the standard field, type Name. My 'Cancel' button is also not working after the override.

How can i bring everything from the default page, but only add a default value to the token(Name) field.

UPDATE - explained further

 Field Label = Token, Field Type = Name, Data Type = Text(80), Indexed, required (cannot be empty)

Name field is required in order to save the record, hence a before trigger won't work here. Name type fields don't take default values and is always a required/mandatory field. So the field Token is a 'text' field which goes like contact.Name, account.Name etc..(goes by .Name) This type of field requires a value upon saving. you cannot also provide a default value. I tried using a workflow, or a before trigger. But these work only after the record is saved but not just before it is saved. I want my user to not input this token every time they create a new record, but pull the value from it's parent object field.

SOLVED: As Brian suggests below, I created a new button. You can use this link URL Hacks My final button URL looks as follows (note always have the retURL or return url) :

/a09/e?CF00NE0000004Nt36={!Contact.Name}&CF00NE0000004Nt36_lkid={!Contact.Id}&Name={!Contact.C_Token__c}&retURL=/{!Contact.Id}

Answer 1

If you're trying to prepopulate fields on the UI when the user tries to insert a new record:

1. In Classic - try using the Web Link option in the new button override option and do some URL hacks as explained here
2. In Lightning (or Classic using Chatter Actions) - you can use Actions to prepopulate fields and that can be your main entry into inserting a new record. There's a great post on that here

---

If you're just trying to set the SObject.Name field, this can be achieved through a before trigger.

Here's a sample if you wanted to set the Opportunity Name to "{Account Name} - {Amount}" anytime the Opportunity was created or updated (i.e. it'll always overwrite the user's attempt to change the name):

trigger MyOppTrigger on Opportunity(before insert, before update) {
    for (Opportunity opp : Trigger.new)
        opp.Name = opp.Account.Name + ' - ' + opp.Amount;
}

Note that if you're trying to pull some other value from the Account lookup field, you'll need to do a separate query to grab that other field, or use a formula field to pull that lookup field's value to the opportunity. Then the opp.Name code would look like this:

opp.Name = opp.Cust_Field_on_Account__c + ' - ' + opp.Amount;

At this point, might as well just add the whole logic into the formula field and just do opp.Name = opp.Opp_Auto_Name_Formula_Field__c