How to use $in in array of embed array mongodb - php

Question

I have photos_comments collection:
{
"_id" : ObjectId(""),
"photo_id" : ObjectId(""),
"content" : "Comment 1",
"is_approved" : "1",
"user" : {
"user_id" : ObjectId(""),
"name" : "",
"avatar" : ".jpg"
},
"likes" : [
{
"user_id" : ObjectId("")
}
],
"like_count" : 1,
"reply_count" : 5,
"replies" : [
{
"reply_id" : ObjectId(""),
"content" : "Reply 1",
"is_approved" : "1",
"user" : {
"user_id" : ObjectId(""),
"name" : "",
"avatar" : ".jpg"
},
"likes" : [
{
"user_id" : ObjectId("")
}
],
"like_count" : 1
},
]
}
I use $in to check if current user like reply comment:
$collection->aggregate(
[
[
'$match' => [
'_id' => new ObjectId($comment_id)
]
],
[
'$project' => [
'replies.reply_id' => 1,
'replies.like_count' => 1,
'replies.content' => 1,
'replies.is_liked' => ['$in' => [['user_id' => $user_id], '$replies.likes']],
'replies.user' => 1,
'replies.created_at' => 1
]
],
['$sort' => ["replies.reply_id" => 1]],
['$limit' => 5]
]);
But replies.is_liked alway return false, although it exist user_id in likes array from replies array embed.
How to fix it? Thanks!
It looks like your post is mostly code; please add some more details.

Answer 1

If you want to alter the array content to add a new field based on a condition, then you want the $map operator, and probably using $addFields if you don't want to restrict or change the rest of the document returned:
$collection->aggregate([
[ '$match' => [
'_id' => new ObjectId($comment_id)
]],
[ '$addFields' => [
'replies' => [
'$map' => [
'input' => '$replies',
'in' => [
'reply_id' => '$$this.reply_id',
'content' => '$$this.content',
'is_approved' => '$$this.is_approved',
'is_liked' => [ '$in' => [ $user_id, '$$this.likes.user_id' ] ],
'like_count' => '$$this.like_count'
]
]
]
]],
... # any other pipeline
])
Or using $mergeObjects if your MongoDB supports it and you prefer:
$collection->aggregate([
[ '$match' => [
'_id' => new ObjectId($comment_id)
]],
[ '$addFields' => [
'replies' => [
'$map' => [
'input' => '$replies',
'in' => [
'$mergeObjects' => [
'$$this',
[ 'is_liked' => [ '$in' => [ $user_id, '$$this.likes.user_id' ] ] ]
]
]
]
]
]],
... # any other pipeline
])
In both cases of course where $user_id is your PHP variable as the singular value in argument to $in, and where the '$$this.likes.user_id' is the MongoDB representation of the array of user_id values in that inner array. Note the array is the second argument and the singular is the first.
The $map operator uses the '$$this' to represent the current element of the array being processed. In both examples this allows re-mapping of the array content, just as the operator name implies.