History Service

Summary

The history service keeps track of lifecycle events in Dendron. It is defined here

Details

Lifecycle events have the following structure

export type HistoryEvent = {
  action: HistoryEventAction;
  source: HistoryEventSource;
  /**
   * Used to further narrow down the source.
   * This is used in {@link LookupProviderV3} as this can be embedded in multiple commands (eg. NoteLookup vs RenameNote)
   * For example, for [RenameNote](https://github.com/dendronhq/dendron/blob/6c98d466536632530399bd45f1220ae725ff3e2f/packages/plugin-core/src/commands/RenameNoteV2a.ts#L52-L52),
   * the id is "rename" whereas for NoteLookup, the id is "lookup"
   */
  id?: string;
  /**
   * Sometimes events have uris attached to them (eg. {@link HistoryEventAction.create})
   */
  uri?: URI;
  /**
   * Arbitrary data that can be passed to the event
  */
  data?: any;
};

Lifecycle Events

LookupProvider

The lookup provider emits events when items have been selected. If there is an error, it will yield an error event.

Source code here.

Consumers of the LookupProvider are usually commands that integrate lookup. You can see an example here.

HistoryService.instance().subscribev2("lookupProvider", {
    id: "lookup",
    listener: async (event) => {
      if (event.action === "done") {
        const data =
          event.data as NoteLookupProviderSuccessResp<OldNewLocation>;
        if (data.cancel) {
          resolve(undefined);
        }
        const _opts: CommandOpts = {
          selectedItems: data.selectedItems,
          ...opts,
        };
        resolve(_opts);
      } else if (event.action === "error") {
        const error = event.data.error as DendronError;
        this.L.error({ error });
        resolve(undefined);
      } else {
        const error = new DendronError({
          message: `unexpected event: ${event}`,
        });
        this.L.error({ error });
      }

      HistoryService.instance().remove("lookup", "lookupProvider");
    },
  });

The reason we use this pub/sub pattern is because the QuickInput widget we use for lookup is asynchronous and we can't just await on the result because QuickInput.show doesn't return anything.

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