Typing off for setPuckInitialHistory's histories

[mkilpatrick]

If you try to pass histories (type History[]) to setPuckInitialHistory when appendData is false, there is a type error.

Type 'History[]' is not assignable to type '[History<Partial<AppState<Data<DefaultComponentProps, DefaultRootFieldProps>>>>, ...History<...>[]]'.
  Source provides no match for required element at position 0 in target.

If appendData is true it works fine though.

The documentation shows the type as History[] too.

Why does InitialHistory's type need the InitialHistoryNoAppend version? The histories type between InitialHistoryNoAppend and InitialHistoryAppend are [History<AS>, ...History<AS>[]] and History<AS>[], respectively.

[chrisvxd]

I believe if appendData is false, then Puck assumes you need at least one item in the histories.

It would be useful to understand your use-case for this in particular

[mkilpatrick]

const [puckInitialHistory, setPuckInitialHistory] = useState<InitialHistory | undefined>();
const localHistories = JSON.parse(localHistoryArray) as History[];
const localHistoryIndex = localHistories.length - 1;
setPuckInitialHistory({
    histories: localHistories,
    index: localHistoryIndex,
    appendData: false,
});

[chrisvxd]

Puck always requires one initial item in the history. It derives an initial app state (called generatedAppState) based on default Puck state.

1. If appendData: true, the generatedAppState is always inserted after the initial histories provided by the user. This ensures there is always at least one item in the history.
2. If appendData: false, then the generatedAppState is not inserted at all. Instead, the user must specify at least one history item.

If you're not providing any history or appending data, then Puck will be unable to determine the initial state. To counter this, I suggest inserting an empty history item.