sObjects: one weird little trick Trailhead doesn’t tell you

The Trailhead modules on “Apex Basics & Database” are – like most of the Trailhead modules – pretty fantastic but they do miss out one weird little trick: using sObjects as maps. This is another handy arrow in your ‘Dynamic DML’ quiver.

The “Manipulating Records with DML” unit has this code snippet:

// Create the account sObject 
Account acct = new Account(Name='Acme', Phone='(415)555-1212', NumberOfEmployees=100);
// Insert the account by using DML
insert acct;

Line 2 is what we’re interested in. It uses a field name and the value that is going to be inserted into the field as key-value pairs like this:

Name=’Acme’

Phone='(415)555-1212′

NumberOfEmployees=100

There’s a clue here. What this means is we can treat an sObject like a map with the field name as the key and the value that is going to be inserted into the field as the value. Like this:

// Create the account sObject 
Account acct = new Account();
acct.put('Name', 'Acme');
acct.put('Phone', '(415)555-1212');
acct.put('NumberOfEmployees', 100);
// Insert the account by using DML
insert acct;
}

Taking this one step further, you can create a utility method that takes a map consisting of field names and field values and creates an Account. Like so:

public static void createAccount(Map fieldValueMap) {
    // Get the metadata so we can do some data type checking
    Map finalMap =  
    Utils.getFieldMetaData(Account.getSObjectType().getDescribe(), fieldValueMap.keySet());
    // Create the account sObject 
    Account acct = new Account();
    for (String field : fieldValueMap.keySet()) {
        // check different data types
        if (finalMap.get(field).getType() == Schema.DisplayType.Integer) {
            acct.put(field, Integer.valueOf(fieldValueMap.get(field)));
        }
        if (finalMap.get(field).getType() == Schema.DisplayType.STRING || finalMap.get(field).getType() == Schema.DisplayType.PHONE) {
            acct.put(field, fieldValueMap.get(field));  
        }   
        // check for other data types ...
    }
    insert acct;
}

Then later on, you can call the method like this:

Map<String, String> dynamicRecord = new Map<String, String>();
dynamicRecord.put('Name', 'Acme4');
dynamicRecord.put('Phone', '(415)555-1212');
dynamicRecord.put('NumberOfEmployees', '100');
createAccount(dynamicRecord);

Good to know

– Utils.getFieldMetaData at line 4 of createAccount is a utility method for getting field metadata. It’s from Jeff Douglas’s excellent blog and the code can be found in the post “Getting Salesforce Field Metadata the Easy Way“.