Iterate over queried lookup fields

Question

Example:

Opportunity Opp = [SELECT Name, Status__c, Zone__c, Invoice__r.Amount__c, Invoice__r.Date__c FROM Opportunity WHERE ID ='006a12nlfoenlew'];

I need to iterate over each field and see if the values are not null. If I want to check only Opportunity fields, I would do this:

Set<String> strFields = new Set<String>{'Name','Status__c','Zone__c'};

for(String s: strFields ){

//This prints the value of each field(included in the set) for the current Opportunity.
System.Debug(logginglevel.error,'*****'+Opportunity.get(s));

}

But, I need to get the values in lookup objects also. If I repeat the same,

Set<String> strFields = new Set<String>{'Invoice__r.Amount__c', 'Invoice__r.Date__c'};

for(String s: strFields ){

//This would throw "System.SObjectException: Invalid field Invoice__r.Amount__c for Opportunity" error.

System.Debug(logginglevel.error,'*****'+Opportunity.get(s));

}

Update: Even though the example I've give is very simple, In the code I'm working on, I've around 40 fields across 5 different look ups, ranging from 3-5 level deep relationships (Ex: Invoice__r.Task__r.Account.Contact.FirstName). I'm querying Opportunity(the base object) and I need to make sure the FirstName on contact is not null.

Is there a way I can iterate over, and get value in each field including lookup fields that are being queried?

Answer 1

You cannot call cross-object get. Take a look at the FieldReference class. It's open source, so you can just copy it into your org. Then you could do:

for (String invoiceField : invoiceFields)
    system.debug(FieldReference.build(invoiceField).getFrom(opportunity);

What you want probably cannot be accomplished in a clean way without recursive logic. If you want to do so without a helper class, you could do something along the lines of:

public with sharing class CrossObject
{
    public static Object get(SObject record, String field)
    {
        if (record == null) return null;
        if (!field.contains('.')) return record.get(field);
        record = record.getSObject(field.substringBefore('.'));
        field = field.substringAfter('.');
        return get(record, field);
    }
}

Answer 2

Try this:

Set<String> invoiceStrFields= new Set<String>{'Amount__c', 'Date__c'};
Invoice__c invoice = Opportunity.Invoice__r;


for(String s: invoiceStrFields){
    System.Debug(logginglevel.error,'*****'+invoice.get(s)); 
}

You should get the Lookup object then you can use the getter with String fields

Answer 3

You need to use dynamic SOQL:

Dynamic SOQL refers to the creation of a SOQL string at runtime with Apex code. Dynamic SOQL enables you to create more flexible applications. For example, you can create a search based on input from an end user, or update records with varying field names.

and the SObject getSObject() method:

Returns the value for the specified field. This method is primarily used with dynamic DML to access values for external IDs.

In your case, the solution will look something like this:

Set<String> strFields = new Set<String>{'Name', 'AccountId', 'Account.Name', 'Account.CreatedDate'};

// First query for the Opportunity record
String queryStr = 'SELECT Id, StageName, CloseDate FROM Opportunity LIMIT 1';
Opportunity opp;

// Now add the referenced fields to the query
for (String field : strFields) {

    queryStr = queryStr.replaceAll(' FROM', ', ' + field + ' FROM');
}

// Now remove the trailing comma if needed
queryStr = queryStr.replaceAll(', FROM', ' FROM');

opp = database.query(queryStr);

for (String field : strFields) {

    String fieldValue;

    if (!field.contains('.')) {

        fieldValue = String.valueOf(opp.get(field));

    } else {

        String objectName = field.replaceAll('__r', '__c').split('\\.')[0];
        String fieldName = field.replaceAll('__r', '__c').split('\\.')[1];

        fieldValue = String.valueOf(opp.getSObject(objectName).get(fieldName));
    }
}

There are some additional checks you should do like ensure no field names are duplicated in the query string, ensure all field names in the set are valid etc. etc.

But that should get you almost there, just tailor it for your custom fields etc.