PersistDataValue

The PersistDataValue transformation stores a value from the dispatch payload (or a constant) into the data layer with a configurable expiry and update policy. On the same dispatch, the effectively persisted value is also injected back into the payload so it is immediately available downstream. If the persistence fails or the update policy prevents the write, the dispatch is returned unchanged.

Requires: TealiumPrismExtensions

Registration

The PersistDataValue transformer is registered automatically when the TealiumPrismExtensions library is linked to your app (via the Objective-C +load mechanism). No additional setup is required.

Programmatic Configuration

Use PersistDataValueSettingsBuilder to configure the transformation:

// Persist a payload value to the data layer (session-scoped by default)
let persistUserId = PersistDataValueSettingsBuilder(id: "persist-user-id")
    .persistFrom(.key("user_id"), to: .key("persisted_user_id"))
    .setScope(.dispatchers(["Analytics", "Collect"]))
    .setOrder(1)

config.setTransformation(persistUserId)

// Persist a constant value, never expire it, and never overwrite once set
let persistAppVersion = PersistDataValueSettingsBuilder(id: "persist-app-version")
    .persistConstant("2.4.0", to: .key("first_seen_version"))
    .setExpiryPolicy(.forever)
    .setUpdatePolicy(.keepFirstValue)
    .setScope(.afterCollectors)
    .setOrder(1)

config.setTransformation(persistAppVersion)

// Persist for a custom duration
let persistCampaign = PersistDataValueSettingsBuilder(id: "persist-campaign")
    .persistFrom(.key("utm_campaign"), to: .key("last_campaign"))
    .setExpiryPolicy(.duration(30.days))
    .setScope(.afterCollectors)
    .setOrder(1)

config.setTransformation(persistCampaign)

Builder methods:

ExpiryPolicy options:

UpdatePolicy options:

JSON Configuration

{
  "transformation_id": "persist-user-id",
  "transformer_id": "PersistDataValue",
  "scope": ["Analytics", "Collect"],
  "order": 1,
  "configuration": {
    "input": { "key": "user_id" },
    "destination": { "key": "persisted_user_id" },
    "duration": -2,
    "update_policy": "allowUpdate"
  }
}

duration encoding:

update_policy values: "allowUpdate" or "keepFirstValue" (case-insensitive).

Constant input:

{
  "configuration": {
    "input": { "value": "2.4.0" },
    "destination": { "key": "first_seen_version" },
    "duration": -1,
    "update_policy": "keepFirstValue"
  }
}