The data layer is a map holding generic information about the application. It uses a standard set of keys so it can be read by any party that understands the specification. The data layer state is updated through its API. For example, an app might start with the following dataLayer:
{
"title": "Original screen title"
}
As the state/data of an app can change, the app can update the dataLayer with a call such as:
dataLayer.push(DataLayer.mapOf( "title", "New screen title" ));Now the data layer contains:
{
"title": "New screen title"
}
After another push happens:
dataLayer.push(DataLayer.mapOf( "xyz", 3));The dataLayer contains:
{
"title": "New screen title",
"xyz": 3
}
The following example demonstrates how array and map merging works. If the original dataLayer
contains:
{
"items": [ "item1", null, "item2", { "a": "aValue", "b": "bValue" }]
}
After this push happens:
dataLayer.push( "items", DataLayer.listOf(null, "item6", DataLayer.OBJECT_NOT_PRESENT, DataLayer.mapOf( "a", null)));The dataLayer contains:
{
"items": [null, "item6", "item2", { "a": null, "b": "bValue" }]
}
Pushes happen synchronously; after the push, changes have been reflected in the model.
When an event is pushed to the data layer, rules for tags are evaluated and any tags matching this event will fire. For example, given a container with a tag whose firing rule is that "event" is equal to "openScreen", after this push:
dataLayer.pushEvent( "openScreen", DataLayer.mapOf());that tag will fire.
Note: Updates to the DataLayer that include the key 'gtm.lifetime' may be persisted. Because of this, it is unsafe to push instances of your own types, or instances outside of your control.
Constant Summary
| String | EVENT_KEY | If a map is pushed containing this key, it's treated as an event, and tags are evaluated. |
Field Summary
| public static final Object | OBJECT_NOT_PRESENT | Values of this type used in a List causes the List to be sparse when merging; it's as if there were no element at that index. |
Public Method Summary
| Object | |
| static List<Object> | |
| static Map<String,Object> | |
| void | |
| void | |
| void | |
| String |
toString()
Returns a human readable string representing the Data Layer object.
|
Inherited Method Summary
Constants
public static final String EVENT_KEY
If a map is pushed containing this key, it's treated as an event, and tags are evaluated.
Fields
public static final Object OBJECT_NOT_PRESENT
Values of this type used in a List causes the List to be sparse when merging; it's as if there were no element at that index.
Public Methods
public Object get (Stringkey)
Returns the object in the model associated with the given key. If the key is not found,
nullis returned.
The key can can have embedded periods. For example: a key of"a.b.c"
returns a map with key"c"in a map with key"b"
in a map with key"a"in the model.
public static List<Object> listOf (Object...objects)
Utility method that creates a list.
For example, the following creates a list containing"object1"and
"object2":
List<Object> list = DataLayer.listOf( "object1", "object2" );
public static Map<String,Object> mapOf (Object...objects)
Utility method that creates a map. The parameters should be pairs of key values.
For example, the following creates a map mapping"key1"to
"value1"and"key2"
to"value2":
Map<String, Object> map = DataLayer.mapOf( "key1", "value1", "key2", "value2" );
Throws
| IllegalArgumentException | if there are an odd number of parameters or a key is not a string |
|---|
public void push (Map<String,Object> update)
Merges the givenupdateobject into the existing data model, calling any listeners
with the update (after the merge occurs).
If you want to represent a missing value (like an empty index in a List), use the
OBJECT_NOT_PRESENTobject.
If another thread is executing a push, this call blocks until that thread is finished.
This is normally a synchronous call. However, if, while the thread is executing the push, another push happens from the same thread, then that second push is asynchronous (the second push will return before changes have been made to the data layer). This second push from the same thread can occur, for example, if a data layer push is made in response to a tag firing.
If theupdatecontains the keyevent,rules will be evaluated and
matching tags will fire.
Note: Updates to the DataLayer that include the key 'gtm.lifetime' may be persisted. Because of this, it is unsafe to push instances of your own types, or instances outside of your control.
Parameters
| update | the update object to process |
|---|
public void push (Stringkey,Objectvalue)
Pushes a key/value pair of data to the data layer. This is just a convenience method that calls
push(DataLayer.mapOf(key, value)).
A key with valueeventwill cause rules to be evaluated and matching tags to be
fired.
Note: Updates to the DataLayer that include the key 'gtm.lifetime' may be persisted. Because of this, it is unsafe to push instances of your own types, or instances outside of your control.
public void pushEvent (StringeventName,Map<String,Object> update)
Pushes an event, along with an update map, to the data layer.
This is just a convenience method that pushes a map containing a keyevent
whose value iseventNamealong with the contents ofupdatevia
push(Map.
Note: Updates to the DataLayer that include the key 'gtm.lifetime' may be persisted. Because of this, it is unsafe to push instances of your own types, or instances outside of your control.