sort orderby array

[giduya]

This are my documents:

{
"_id": "621113c8166924399446756e",
"metadata":
{
"country": "mexico",
"lenguage": "spanish",
"continent": "america",
"demographics":
[
"population": 3,000,000,
"minority" : "white people"
],
[
"population": 5,000,000,
"minority" : "indigenous people"
],
[
"population": 500,000,
"minority" : "black people"
],
}

how can i order by population:

$pagination = Countries::orderBy('continent'.'asc')->orderby('country','asc')->orderby('demographics.population','asc');

i get this error:
Executor error during find command :: caused by :: cannot sort with keys that are parallel arrays

[nicohell]

Hi Giduya,
Well the message tells you the issue "cannot sort with keys that are parallel arrays" demographics should be an array of objects and you should use project & unwind in aggregate.

You data should looks like :

{
  "_id": {
    "$oid": "62b02d3c0dcd9192dfcd3f29"
  },
  "metadata": {
    "country": "mexico",
    "lenguage": "spanish",
    "continent": "america"
  },
  "demographics": [
    {
      "population": 3000000,
      "minority": "white people"
    },
    {
      "population": 5000000,
      "minority": "indigenous people"
    },
    {
      "population": 500000,
      "minority": "black people"
    }
  ]
} 

and your aggregate :

db.DB.aggregate([{ "$match" : { 'metadata.continent': 'america' }},{"$project" : {demographics : 1 }}, { "$unwind" : "$demographics" }, { "$sort" : { "demographics.population" : -1 }}]);

Apply this in you PHP framework...