[base-controller] ControllerMessenger selectors skip initial value #3649
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Gudahtt
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Dec 22, 2023
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
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Gudahtt
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Dec 22, 2023
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
Gudahtt
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Dec 22, 2023
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
Gudahtt
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Jan 3, 2024
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
Gudahtt
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Jan 8, 2024
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
Gudahtt
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Jan 9, 2024
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
Gudahtt
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Jan 9, 2024
The "selectors" feature of the `ControllerMessenger` did not work correctly for the first event published after subscribing, because the original value of the payload (at time of subscribing) was not available for comparison. To address this, a `registerInitialEventPayload` method has been added to the `ControllerMessenger` and `RestrictedControllerMessenger`. This allows registering a function that returns the "event payload state" at a given time, which is used internally by the `subscribe` method to correctly initialize the payload cache when a subscriber with a selector is added. This ensures that the selector workds correctly even for the initial state change, in that it will return the correct previous value, and not fire at all if the selected piece of state is unchanged. In a later PR, `BaseControllerV2` can be updated to register an event payload for the `stateChange` event. This will fix this flaw for the `stateChange` event of each controller. Fixes #3649
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The ControllerMessenger
subscribefunction accepts an optional "selector" which can act like a Redux selector in that it narrows the state to just the subset that is of interest to that subscriber. The subscriber isn't invoked unless that specific piece of state is updated.However, these selectors don't consider the initial state. They will always run upon the first state change, regardless what has changed.
We should update the
ControllerMessengerto cache the initial state as well, so that we can use that for a point of comparison even on the first update.The text was updated successfully, but these errors were encountered: