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CollectionUtils
Library of generic, type safe collection methods.
Group Collection Recipes
This is a generic, reusable but still typesafe method for generating a Map<Id, Some_SObject> from a list. This code is intended to prevent developers from writing countless for loops just to transform a list of sobjects into a map where the key is something other than the object's Id field. In order to maintain type safety, this accepts a generic list of sObjects. It then determines the concrete sObject type of the incoming lists' first object. This is used to create a new map of type Map<Id, firstItemsType> However, to maintain the generic nature of this, that concretely typed map is cast to a Map<id, sObject>. We then use generic sObject methods of .get() and .set() to construct the map. This works for two reasons: * Because we can always go from a concrete type, say Account to the generic sObject type * When you construct a concrete object but cast it to an sObject, even in a map context, the concrete sObject type is not lost.
| Param | Description |
|---|---|
key |
String representation of the field name to use as the Key. This must be of type Id for this method. |
incomingList |
Any list of objects that can be cast to a list of sObjects |
| Type | Description |
|---|---|
Map<Id,SObject> |
Map<Id, sObject> |
Contact[] contacts = [SELECT AccountId, firstName, lastName FROM Contact LIMIT 50];
Map<Id, Contact> contactsByAccountId = (Map<Id, Contact>) CollectionUtils.idMapFromCollectionByKey('accountId', contacts);public static Map<String,SObject> stringMapFromCollectionByKey(String key, List<SObject> incomingList)
Method functions as the above methods do, but returns a map whose keys are strings. The key parameter here must be something castable to string. Note, you are responsible for ensuring the uniqueness of the key's value when using this.
| Param | Description |
|---|---|
key |
String field name of a field who's value is castable to String. |
incomingList |
List of incoming sObjects to build the map from |
| Type | Description |
|---|---|
Map<String,SObject> |
Map<String, sObject> |
Contact[] contacts = [SELECT AccountId, firstName, lastName FROM Contact LIMIT 50];
Map<String, Contact> contactsByAccountId = (Map<String, Contact>) CollectionUtils.StringMapFromCollectionByKey('shippingStreet', contacts);public static Map<Id,List<SObject>> mapFromCollectionWithCollectionValues(String key, List<SObject> incomingList)
This method accepts an incoming List of sObjects and generates a Map<id,List<sObject>>. Useful for not littering your codebase full of for loops to, for instance, take a list of Contacts and get a Map of AccountIds to a List<Contacts>.
| Param | Description |
|---|---|
key |
String name of an field that is of the ID type. |
incomingList |
List of sObjects to build the map from. |
| Type | Description |
|---|---|
Map<Id,List<SObject>> |
Map<Id, List<sObject>> |
Contact[] contacts = [SELECT AccountId, firstName, lastName FROM Contact LIMIT 50];
Map<Id, List<Contact>> contactsByAccountId = (Map<Id, List<Contact>>) CollectionUtils.idMapFromCollectionByKey('accountId', contacts);