Using Page State (Advanced)

Page State is in-memory storage that’s available during a page session. There are three Page State namespaces to isolate information:

• Private — accessible only for bricks attached to the starter brick

• Mod — accessible to all bricks in the mod

• Public — accessible to all bricks

There are two bricks to write/read directly from Page State:

• Set shared page state

• Get shared page state

Additionally, there are other bricks that can connect to the Page State

• Trigger Starter Brick: can listen for changes to Page State

• Sidebar Starter Brick: can re-render on changes to Page State

• Custom Form: can be synchronized to Mod Variables/Page State

• Display Temporary Information: can re-render on changes to Page State

• With Async Async Page State: runs one or more bricks asynchronously and keeps track of the result in a Mod Variable

Getting Page State

The “Get Shared Page State” brick retrieves all data for the chosen namespace and assigns it to a Local Variable.

Using “Get Shared Page State” can be useful to take a snapshot of multiple Mod Variables at a single point in time.

Setting Page State

The “Set Shared Page State” brick provides full control over how to update Page State, including Mod Variables stored in the mod namespace.

Merge Strategy

The Merge Strategy input of the “Set shared page state” brick controls how the values provided impact existing values:

• Shallow (default): properties provided overwrite existing properties. Other properties are preserved

• Replace: replace the page state with the new values

• Deep: merge properties, including nested objects. For arrays, items are merged pairwise. If two values are different types, the value is replaced

Example: Replace State

Before:

hasRun: false
message: "Some text"

Update

After

# The message field is removed, because the whole state is replaced
hasRun: true

Example: Shallow Merge

Before

hasRun: false
message: "Some text"

Update

After

hasRun: true
# The `message` key is not modified
message: "Some text"

Example: Deep Merge

In “deep” merge mode, arrays items are merged together pair-wise. (They are not appended)

Before: State

hasRun: false
exampleObject:
  key1: "Text value"  

Before: @data

exampleObject:
  key2: "Key from @data object"

Update

After

hasRun: false
exampleObject:
  key1: "Text value"
  # key2 is deep merged into exampleObject
  key2: "Key from @data object"