how to loop over an array and get data for each element? - with mongoose & node.js-CodePudding

I am trying to build a social network. I have a collection of "connections"/"friend requests". the schema is as follows:

  {
    senderId: { type: String },
    receiverId: { type: String },
    approved: { type: Boolean },
  },

when the person didn't approve the connection yet, the connection is marked with "pending". when the user enter to the website, i get all the pending connections people sent him, with this command:

    const requestsPending = await Connection.find({
      receiverId: userId,
      approved: false,
    });

the thing is, in the backend, I want to get the details of the people who send the friend requests (so I can show their name picture). I want to loop over the pending requests array, and get the extra data of the user who sent the request.

  await User.findById(requestsPending[0][senderId]);

any idea how to do it for each element? what's the best approach? or any idea how to do it more efficiently?

thank you.

CodePudding user response：

this seems to work:

var requestsPendingWithUsersData = await Promise.all(
  requestsPending.map(async (item) => {
    const userData = await User.findById(item.senderId);
    return {
      item,
      senderData: { picture: userData.picture, name: userData.username },
    };
  })
);

CodePudding user response：

await User.find({
'senderId': { $in: [
    101,102,103,...
    ]}
})

You can try something like the above, where you pass an array of senderID to $in. The $in clause is similar to like operator in SQL.

If the senderId is an ObjectId, pass them as ObjectID types

await User.find({
'senderId': { $in: [
    mongoose.Types.ObjectId(<senderID>),
    ]}
})

If the mongo Document is heavier/larger, use lean() at the end of the query. Enabling the lean option tells Mongoose to skip instantiating a full Mongoose document.

await User.find({
'senderId': { $in: [
    101,102,103,...
    ]}
}).lean()