Firebase 实时数据库 - 过滤查询不在客户端 Web/React

Question

Quite new to Firebase and I'm facing some issue on the logic on querying/filtering the needed requests.

I have my users stored in the /users and they have a list of projects such as:

users : {
  userA : {
    projects: {
      projectId1: true,
      projectId2: true
    },
    ...
  }
...
}

And obviously I have the projects as such:

projects: {
  projectId1: {
    name: "bla"
  }
  ...
}

I want for a user to query all the projects that are in his projects list based on their Ids. Right now I only succeed to query every single projects of the database and their filter on the client side but obviously this has some serious security implication and loading time as well as I don't want anyone to query all the projects and get them. I can add security rules but then I have access to nothing as I can't query /projects/ anymore but need to be specific.

I'm using https://github.com/CSFrequency/react-firebase-hooks/tree/master/database

and getting the data as such:

  const [projects, loading, error] = useListVals(firebase.db.ref("projects"), {
    keyField: "uid",
  });

And so would like to be able to add an array of projected in this request like where({ id is included in [projectsId]})

Answer 1

You'll need to load each individual project for the user separately, pretty much like a client-side join operation. This is not nearly as slow as you may think, as Firebase pipelines the operations over a single connection .

I don't see anything built into the library you use for such client-side joins, but in regular JavaScript it's something like this:

let userRef = firebase.database().ref('users').child(firebase.auth().currentUser.uid);
userRef.once('value').then((projectKeys) => {
  let promises = [];
  projectSnapshot.forEach((projectKey) => {
    let key = projectKey.key;
    let projectRef = firebase.database().ref('projects').child(key);
    promises.push(projectRef.once('value');
  });
  Promise.all(promises).then((snapshots) => {
    console.log(snapshots.map(snapshot => snapshot.val()));
  });
});