Collection management functions collection-management-functions
About query collection functions
The expression language also introduces a set of functions to query collections. These functions are explained below.
In the following example, let鈥檚 use the event payload containing a collection:
{
"_experience":{
"campaign":{
"message":{
"profile":{
"pushNotificationTokens":[
{
"token":"token_1",
"application":{
"_id":"APP1",
"name":"MarltonMobileApp",
"version":"1.0"
}
},
{
"token":"token_2",
"application":{
"_id":"APP2",
"name":"MarketplaceApp",
"version":"1.0"
}
},
{
"token":"token_3",
"application":{
"_id":"APP3",
"name":"VendorApp",
"version":"2.0"
}
}
]
}
}
}
},
"timestamp":"1536160728"
}
The all(<condition>) function
The all function enables the definition of a filter on a given collection by using a boolean expression.
<listExpression>.all(<condition>)
For example, among all the app users, you can get the ones using IOS 13 (boolean expression 鈥渁pp used == IOS 13鈥). The result of this function is the filtered list containing items matching the boolean expression (example: app user 1, app user 34, app user 432).
In a Data Source Condition activity you can check if the result of the all function is null or not. You can also combine this all function with other functions such as count. For more information, see Data Source Condition activity.
Example 1
We want to check if a user has installed a specific version of an application. For this we get all the push notification tokens associated with mobile applications for which the version is 1.0. Then, we perform a condition with the count function to check that the returned list of tokens contains at least one element.
count(@event{LobbyBeacon._experience.campaign.message.profile.pushNotificationTokens.all(currentEventField.application.version == "1.0").token}) > 0
The result is true.
Example 2
Here we use the count function to check if there are push notification tokens in the collection.
count(@event{LobbyBeacon._experience.campaign.message.profile.pushNotificationTokens.all().token}) > 0
The result is true.
count(@event{LobbyBeacon._experience.campaign.message.profile.pushNotificationTokens.token})
The result of the expression is 3.
-
When the filtering condition in the all() function is empty, the filter will return all the elements in the list. **However, in order to count the number of elements of a collection, the all function is not required.
-
currentEventFieldis only available when manipulating event collections,currentDataPackFieldwhen manipulating data source collections andcurrentActionFieldwhen manipulating custom action response collections.When processing collections with
all,firstandlast, we loop on each element of the collection one by one.currentEventField,currentDataPackFieldandcurrentActionFieldcorrespond to the element being looped.
The first(<condition>) and last(<condition>) functions
The first and last functions also enable the definition of a filter on the collection while returning the first/last element of the list that meets the filter.
<listExpression>.first(<condition>)
<listExpression>.last(<condition>)
Example 1
This expression returns the first push notification token associated with mobile applications for which the version is 1.0.
@event{LobbyBeacon._experience.campaign.message.profile.pushNotificationTokens.first(currentEventField.application.version == "1.0").token}
The result is token_1.
Example 2
This expression returns the last push notification token associated with mobile applications for which the version is 1.0.
@event{LobbyBeacon._experience.campaign.message.profile.pushNotificationTokens.last(currentEventField.application.version == "1.0").token}
The result is token_2.
The at(<index>) function
The at function allows you to reference a specific element in a collection according to an index.
Index 0 is the first index of the collection.
<listExpression>.at(<index>)
Example
This expression returns the second push notification token of the list.
@event{LobbyBeacon._experience.campaign.message.profile.pushNotificationTokens.at(1).token}`
The result is token_2.