Confused with using action and subAction

[jembach]

Hi,

I'm confused with using the action and subAction. Sometimes it works and sometimes not.

For example this batch delete does not work: await database.action(action => action.subAction(() => database.batch(allRecords))); It will throw every time the error: Unhandled Promise Rejection: Diagnostic error: Database.batch() can only be called from inside of an Action. See docs for more details.

Also this piece of code doesn't work: await database.action(action => action.subAction(() => currentUser.addChats(result))); Running it the first time it will crash. But when it runs seconds, it runs. but I don't know why.

Can anyone give me a good example and explanation, how to run actions correctly.

[rkrajewski]

Hi @jembach,

Not sure what currentUser.addChats does, but at first look, it seems the subAction callbacks don't return an action.

const subAction = () => database.action(() => {
  database.batch(allRecords)
})

await database.action(action => action.subAction(subAction))

docs -> https://nozbe.github.io/WatermelonDB/Actions.html?highlight=subAction#calling-actions-from-actions

[jembach]

Hi @rkrajewski,

the currentUser.addChats contains the following code:

    for (let i = 0; i < chats.length; i += 1) {
      const chat = chats[i];
      let [chatLocal] = await this.chats.extend(Q.where('remote_id', chat.id)).fetch();

      if (!chatLocal) {
        chatLocal = await chatsCollection.create(newChat => {
          newChat.remoteId = chat.id;
          newChat.name = chat.name;
          newChat.type = chat.type;
          newChat.role = chat.role;
          newChat.invited_at = chat.invitedAt;
          newChat.created_at = chat.createdAt;
          newChat.account.set(this);
        });
        await this.subAction(() => chatLocal.setAvatar(chat.avatar));
      } else {
        await this.subAction(() => chatLocal.setAvatar(chat.avatar));
      }
    }

Not sure what currentUser.addChats does, but at first look, it seems the subAction callbacks don't return an action.

I doesn't know, that it has to return an action. Does this code returns an action? I'm not sure

[rkrajewski]

I assume currentUser is a model, so you can simply decorate addChats method with @action decorator.

class CurrentUser extends Model {
  /* ... class definition */

  @action addChats() {
     // your code goes here
  }
}

[jembach]

Yes of course. I have also done this. Nevertheless the error occures.

[rkrajewski]

And how about setAvatar - is it an @action as well? Besides, I'm sure what does the code of setAvatar do. Does it work if chatLocal has been found, or doesn't for both cases? Can you provide more specific example of your code?