MongoDB query on multiple array of objects

The query object should look like this for your example

{  $or: [    {      original: { name: "English", code: "en" },      target: {        $in: [{ name: "Japanese", code: "jp" }, { name: "Chinese", code: "cn" }]      }    },    {      original: { name: "Korean", code: "ko" },      target: {        $in: [{ name: "Japanese", code: "jp" }, { name: "English", code: "en" }]      }    }  ]}

So you will have to construct the condition from prefLang like this

const query = {  $or: perfLang.map(lang => ({    original: lang.main,    target: { $in: lang.secondary }  }))}const post = await Post.find(query)

Tip:

If the language objects have a strict schema, you can define them like this

const LanguageSchema = new mongoose.Schema({  name: String,  code: String}, {  _id: false})const UserSchema = new mongoose.Schema({  //...  googleId: String,  name: String,  Language: [{ main: LanguageSchema, secondary: [LanguageSchema] }]})

Sounds like the usage of basic boolean logic would suffice:

const prefLang = req.user.Language;let conditions = [];prefLang.forEach((langObj) => {    let tragetLangs = langObj.secondary.map(lang => lang.code);    conditions.push({        $and: [            {                "original.code": langObj.main.code,            },            {                "target.code": {$in: tragetLangs}            }        ]    })})// you should check conditions !== empty array.const post = await Post.find({$or: conditions})