Mongodb unwind nested documents

Question

I have a document in MongoDB and I'm trying to unwind it in PHP. I want to unwind a document that has a subdocument that contains yet anothersubdocument. I was able to do this succesfully if the document only contains strings and numbers, but if it contains another subdocument then I can't get it to work. I get this error: ``` exception: $unwind: value at end of field path must be an array ``` Can you not unwind a subdocument that contains another level of subdocument? If not, how would you go about doing this? Thanks in advance! This is the query: ``` $project = array( '$project' => array( '_id' => 1, 'items' => 1, ) ); $unwind = array( '$unwind' => '$items' ); $query = $mongo->store->aggregate($project,$unwind_items); ``` This is the structure: ``` { "_id": { "$oid": "526fdc1fd6b0a8182300009c" }, "items": [ { "quantity": "1", "category_id": { "$oid": "526fdc1fd6b0a81823000029" }, "category": "test", "images": [ { "name": "9by9easy.PNG", "path": "upload_files/nibh-vulputate-mauris-co…

Accepted Answer

I know that what you're trying to do is possible with MongoDB. The `aggregate()` command can take as many arguments as you need.

In the mongo shell, a command like this

```
db.collection.aggregate(
  { $project: {
    _id: 1,
    items: 1
  } },
  { $unwind: '$items' },
  { $unwind: '$items.images' }
);
```

will unwind the `items` subdocument, then the `images` subdocument.

Based on the code in your question, perhaps this will work

```
$project = array(
  '$project' => array(
    '_id' => 1,
    'items' => 1,
  )
);

$unwind_items = array(
  '$unwind' => '$items'
);

$unwind_images = array(
  '$unwind' => '$items.images'
);

$query = $mongo->store->aggregate($project,$unwind_items,$unwind_images);
```

Mongodb unwind nested documents

Solution

Problem