How to insert into an array in MongoDB using Mongoose?

Question

How to insert into an array in MongoDB using Mongoose?

I have an issue with my model where I am attempting to push an array to an empty array, but for some reason the changes are not reflected in Compass.

Various approaches were tried to remedy this situation such as setting the type of user_list property to array and initializing it as an empty array using []. Additionally, deleting and recreating the entire database was done to rule out any memory-related problems.

Model:

const guildSchema = new Schema({
    guild_name: String,
    guild_id: { type: String, unique: true },
    ...
    user_list: []
})

Fetching the array and attempting to push:

bot.on("guildUpdate", (oldGuild, newGuild) => {
    let userList = newGuild.fetchMembers().then(function(results){ console.log(results.members.keyArray()); userList = results.members.keyArray();
        Guild.findOneAndUpdate({guild_id: oldGuild.id}, {"$set": {"guild_name": newGuild.name, "guild_icon": newGuild.iconURL}}, {"$push": {"user_list": userList}}, function(err) {
            if (err) throw (err);
        });
    }).catch(console.error)
})

console.log(results.members.keyArray())

displays the desired array without any issues. Furthermore, updates made using $set are visible in Compass. However, the problem lies specifically in pushing to user_list, as Compass fails to reflect these changes and continues to display a blank array post-update.

javascript mongodb mongoose discord.js

Answer 1

Answer №1

Issues are arising because the $push operator was mistakenly placed as a 3rd argument in the update query, when it should actually be included in the 2nd argument with $set. The 3rd argument is intended for update query options such as new and upsert.

Here is the revised code snippet:

Guild
    .findOneAndUpdate({
        guild_id: oldGuild.id
    }, {
        "$set": {"guild_name": newGuild.name, "guild_icon": newGuild.iconURL},
        "$push": {"user_list": userList} // This line should be part of the second argument
    }, function(err) {
        if (err) throw err;
    });

Additionally, ensure that you have defined your array in the schema along with its type.

const guildSchema = new Schema({
    guild_name: String,
    guild_id: { type: String, unique: true },
    ...
    user_list: [String]//if type is String
})

Answer 2

Issues are arising because the $push operator was mistakenly placed as a 3rd argument in the update query, when it should actually be included in the 2nd argument with $set. The 3rd argument is intended for update query options such as new and upsert.

Here is the revised code snippet:

Guild
    .findOneAndUpdate({
        guild_id: oldGuild.id
    }, {
        "$set": {"guild_name": newGuild.name, "guild_icon": newGuild.iconURL},
        "$push": {"user_list": userList} // This line should be part of the second argument
    }, function(err) {
        if (err) throw err;
    });

Additionally, ensure that you have defined your array in the schema along with its type.

const guildSchema = new Schema({
    guild_name: String,
    guild_id: { type: String, unique: true },
    ...
    user_list: [String]//if type is String
})

How to insert into an array in MongoDB using Mongoose?

Answer №1

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