[{"_id":ObjectId("61223b3c88e21fe0ee69d689"),"username":"randomUserName","email":"random@email.com","pictureUrl":"some/url/to/the/user/picture/username","role":"admin","candidates":[{"_id":ObjectId("612242cd11a7f1ebc6a18661"),"candidateName":"some candidates name","candidateId":123,"candidateInfo":[{"_id":ObjectId("612242cd11a7f1ebc6a18662"),"currentSituation":"3","motivationToChange":"3","postSavingDate":ISODate("2021-08-22T12:27:57.490Z")},{"_id":ObjectId("612242cd11a7f1ebc6a04854"),"currentSituation":"6","motivationToChange":"7","postSavingDate":ISODate("2021-08-22T13:56:57.490Z")}],"availableNow":false,"mainSkills":"MM"},{"_id":ObjectId("612261abf7b68bfaf56345df"),"candidateName":"some other guy","candidateId":1234,"candidateInfo":[{"_id":ObjectId("612261abf7b68bfaf56345e0"),"currentSituation":"dunno","motivationToChange":"no idea","postSavingDate":ISODate("2021-08-22T14:39:39.161Z")}],"availableNow":false,"mainSkills":"JavaScript"}],"__v":0},{"_id":ObjectId("61223b3c88e21fe0ee69d699"),"username":"randomUserName","email":"random1@email.com","pictureUrl":"some/url/to/the/user/picture/username","role":"admin","candidates":[{"_id":ObjectId("612242cd11a7f1ebc6a18661"),"candidateName":"some candidates name","candidateId":123,"candidateInfo":[{"_id":ObjectId("612242cd11a7f1ebc6a18662"),"currentSituation":"3","motivationToChange":"3","postSavingDate":ISODate("2021-08-22T12:27:57.490Z")},{"_id":ObjectId("612242cd11a7f1ebc6a04854"),"currentSituation":"6","motivationToChange":"7","postSavingDate":ISODate("2021-08-22T13:56:57.490Z")}],"availableNow":false,"mainSkills":"MM"},{"_id":ObjectId("612261abf7b68bfaf56345df"),"candidateName":"some other guy","candidateId":1234,"candidateInfo":[{"_id":ObjectId("612261abf7b68bfaf56345e0"),"currentSituation":"dunno","motivationToChange":"no idea","postSavingDate":ISODate("2021-08-22T14:39:39.161Z")}],"availableNow":false,"mainSkills":"JavaScript"}],"__v":0}]

db.collection.aggregate([{"$match":{email:"random@email.com"}},{"$unwind":"$candidates"},{"$match":{"candidates.candidateId":1234}}])