[SalesForce] Get Custom Object full Id

You can start by defining an Account object that you would refer in your createShipment method.

public with sharing class ShipmentExtension {

    ApexPages.StandardController standardController;
    String accountId;
    public Account objAccount {get; set;}

Next, in your constructor you can initialize objAccount.

public ShipmentExtension(ApexPages.StandardController standardController) {
        this.standardController = standardController;
        this.accountId = ApexPages.currentPage().getParameters().get('accountid');
        this.carrier = 'Private Freight'; /* Default Option */

if(!string.isEmpty(this.accountId)){
            objAccount = [SELECT Id, Name, Owner.Name, ShippingStreet, ShippingCity, ShippingCountry, ShippingState, ShippingPostalCode FROM Account
                WHERE Id = :this.AccountId];
        } else {
            objAccount = new Account();
        }

    }

In your VF page, you would need to use {!objAccount.} instead of {!Account.}

In you createShipment() method, you would be able to get the updated values when you refer the objAccount object.

new_shipment.Account__c = objAccount.Id;

Finally, instead of returning null, you would return the PageReference of the new shipment record.

Ok, so I found the problem. It was in this line:

return new PageReference('/setup/ui/recordtypeselect.jsp?ent=Account&nooverride=1');

When I removed the override of the new button and tried to create a new Account, I saw this URL:

https://cs18.salesforce.com/setup/ui/recordtypeselect.jsp?ent=Account&retURL=%2F001%2Fo&save_new_url=%2F001%2Fe%3FretURL%3D%252F001%252Fo

Note this save_new_url parameter in there. After I added it to my PageReference everything works as it is supposed to(some profiles get a custom VF page and others go to standard record type selection and standard new layout):

return new PageReference('/setup/ui/recordtypeselect.jsp?ent=Account&nooverride=1&save_new_url=%2F001%2Fe');

And actually I don't even need this if anymore(that checks for RecordType parameter), so the code was reduced to this:

public PageReference redirect() {
    if (!shouldSkipRecordTypeSelection(u)) { // a simple if that checks user's profile and returns true if record type selection should be skipped
        return new PageReference('/setup/ui/recordtypeselect.jsp?ent=Account&nooverride=1&save_new_url=%2F001%2Fe');
    }
    return null;
}

EDIT

As sfdcweb mentioned is his comment, this will not work for custom objects by simple changing the ent property to MyCustomObject__c.

To make it work for custom objects too you will have to use the 15 character id of that custom object. To find it, go to:

• Setup
• Create
• Objects
• Select your object and check the URL in your browser(for example: https://cs87.salesforce.com/01I8E0000008XjE?setupid=CustomObjects)
• This is the id that we need(01I8E0000008XjE)

Then, just replace the ent=Account with ent=01I8E0000008XjE