Apex: Dynamically get fields for an SObject - no hardcoding

Question

It states in Salesforce Apex docs that I can get fields for a particular SObject (standard or custom) in the following way:

Map<String, Schema.SObjectField> M = Schema.SObjectType.Custom__c.fields.getMap();

But this requires hardcoding. as I need to hardcode the API name of the SObject : Schema.SObjectType.

Is there a way to access all fields on an SObject dynamically without hard coding? I am getting a list of all SObjects in my org by calling Schema.getGlobalDescribe(), but this leaves me with API names of individual SObjects. There is no way to get all those SObject's field info dynamically. Am I missing something or it is just not possible?

I want something like:

List <Schema.SObjectField> fieldList = Schema.SObjectType.get(SObject_API_Name).fields;

Answer 1

You don't need to hard code the Object name as you have specified, you can indeed do it dynamically, for example:

SObjectType accountType = Schema.getGlobalDescribe().get('Account');
Map<String,Schema.SObjectField> mfields = accountType.getDescribe().fields.getMap();

Answer 2

The docs suggest you use the newer Schema.describeSObjects(List) method - that lets you pass one or more names of objects as a list, and get back the results. Here's the sample code:

// sObject types to describe
String[] types = new String[]{'Account','Merchandise__c'};
// Make the describe call
Schema.DescribeSobjectResult[] results = Schema.describeSObjects(types);
System.debug('Got describe information for ' + results.size() + ' sObjects.');
// For each returned result, get some info
for(Schema.DescribeSobjectResult res : results) {
    System.debug('sObject Label: ' + res.getLabel());
    System.debug('Number of fields: ' + res.fields.getMap().size());
    System.debug(res.isCustom() ? 'This is a custom object.' : 'This is a standard object.');
    // Get child relationships
    Schema.ChildRelationship[] rels = res.getChildRelationships();
    if (rels.size() > 0) {
        System.debug(res.getName() + ' has ' + rels.size() + ' child relationships.');
    }
}

Answer 3

You can use Schema.SObjectType to get the object type dynamically:

String obj = 'Account';

Map<String,Schema.SObjectType> gd = Schema.getGlobalDescribe(); 
Schema.SObjectType sobjType = gd.get(obj); 
Schema.DescribeSObjectResult describeResult = sobjType.getDescribe(); 
Map<String,Schema.SObjectField> fieldsMap = describeResult.fields.getMap(); 

Answer 4

String sobjectname = 'Case' ; //object api name
String fieldapiName = 'Status'; //Field api name
String fieldTypeName = Schema.getGlobalDescribe().get(sobjectname).getDescribe().fields.getMap().get(fieldApiName).getDescribe().getType().name().toupperCase(); 
System.debug('*** fieldTypeName = ' + fieldTypeName);       

Answer 5

There is a way to access all fields on an SObject dynamically without hard coding:

Schema.SObjectField result = Schema.getGlobalDescribe().get('yourObjectName as a string').getDescribe().fields.getMap().get('yourFieldName as a string');

Did it not work in 2013 ?

#archeology

Answer 6

In some orgs with a lot of objects processing time for getGlobalDescribe can consume a lot of time. You can use this instead:

SObjectType accountType = ((SObject) Type.forName('Account').newInstance()).getSObjectType();

It is consumes 1 ms for my org instead of around 60 ms for getGlobalDescribe

Answer 7

The Summer '16 release has a nice function to retrieve populated fields from an object: getPopulatedFieldsAsMap()

I had a simple use case of generating a CSV file from an arbitrary list of sObjects for which it provided an easy solution.

Using getPopulatedFieldsAsMap() you can retrieve a map of field names and their corresponding values without knowing the object type.

sObject data = [SELECT Id, Name FROM Lead LIMIT 1];
Map<String, Object> fieldsAndValues = data.getPopulatedFieldsAsMap();