Dynamically get required fields with JS Remote Objects

Question

I'm designing a VF SPA that uses remote objects. Much of the page is dynamic, and I use user input to define which sObjects I look up. I wanted to know how, given a user input for a sObj, I can return the fields on that object as well as which are "nillable"/required.

A simple example of this would be a page that allows a user to create a new sObj. The user can select the type of sObj they would like to create, i.e. Contact, and the page would render all of the required fields on that sObj.

Can this be done solely via remote objects?

If not, perhaps the way to go is to use remoting and pass an apex method an object type and have the method return an array of fields that are required? In that case, how do I use javascript remote objects where you have to define which fields you want to pull from each object ()? Is it possible to just pull all fields and then, depending on the results from the remote apex class, use only a subset of them?

Thank you!

Answer 1

I approach a similar problem in my SObjectFactory test utility with a RequiredFieldsCache, but you can adopt a somewhat simpler approach because you don't care about the values for a particular field.

public class NonNillableFields
{
    public List<SObjectField> get(SObjectType sObjectType)
    {
        return cache.containsKey(sObjectType) ?
            cache.get(sObjectType) : new List<SObjectField>();
    }
    public List<String> getFieldPaths(SObjectType sObjectType)
    {
        List<String> fields = new List<String>();
        for (SObjectField field : get(sObjectType)
            fields.add(String.valueOf(field));
        return fields;
    }
    static Map<SObjectType, List<SObjectField>> cache = 
        new Map<SObjectType, List<SObjectField>>
    {
        Account.sObjectType => new List<SObjectField>
        {
            Account.Name, Account.ContactId // etc.
        }
    }
}

Then you can use this cache in a variety of ways, but particularly in your controller/extension.

public with sharing class MyExtension
{
    @RemoteAction
    public static List<String> getRequiredFields(String requestedType)
    {
        SObjectType sObjectType = Schema.getGlobalDescribe().get(requestedType);
        return NonNillableFields.getFieldPaths(sObjectType);
    }
}

I think you need to use List<String> because JSON.serialize won't work on SObjectField.