Query search element array in mongo

Question

[MONGO] I have a collection of places which is like this :

[
    { item: "journal",tags: ["blank", "red","blue","yellow"]},
    { item: "notebook",tags: ["red", "pink","green"]},
    { item: "paper", tags: ["red", "blank", "plain","black"]},
    { item: "planner",tags: ["blank", "blue","gray"]},
    { item: "postcard",tags: ["blue"] }
]

I want search for tags with 1 array search:["red", "blank","black"], how to get items, which the tags contains at least 1 element on aray search. and sorting .

expect result:

[
    { item: "paper",tags: ["red", "blank", "plain","black"]},
    { item: "journal",tags: ["blank", "red","blue","yellow"]},
    { item: "notebook",tags: ["red", "pink","green"]},
    { item: "planner", tags: ["blank", "blue","gray"]},
]

then please make your question clear and use proper tags, as it's confusing right now what exactly you want — Kristianmitk, Apr 24 '18 at 09:13
Please clarify: Do you want a search query that returns all items that match *any* ot these tags, i.e. any that are assigned to "red", "blank", *or* "black"? — Alexander, Apr 24 '18 at 09:17
Possible duplicate of [https://stackoverflow.com/questions/44182548/mongo-sort-by-count-of-matches-in-array ](Mongo Sort by Count of Matches in Array) — Afridi, Apr 24 '18 at 09:44

Alexander · Accepted Answer · 2018-04-24T10:09:23.830

If you want to find all documents in a collection myitems, you can use the $or operator, an projection and the sort function.

Here's the query how to find for any element that either has the tag "red", "blank" or "black":

db.myitems.aggregate([
  {$project : 
    {tags: 1, item: 1, tag_count: {$size: "$tags" } }
  }, 
  {$match: 
    {$or: [{tags: "red"}, {tags: "blank"}, {tags: "black"}]} 
  }, 
  {$sort: {"tag_count": -1} } 
]);

This will return something like this:

{ "item" : "journal", "tags" : [ "blank", "red", "blue", "yellow" ], "tag_count" : 4 }
{ "item" : "paper", "tags" : [ "red", "blank", "plain", "black" ], "tag_count" : 4 }
{ "item" : "notebook", "tags" : [ "red", "pink", "green" ], "tag_count" : 3 }
{ "item" : "planner", "tags" : [ "blank", "blue", "gray" ], "tag_count" : 3 }

Explanation:

This uses the Aggregation pipeline in MongoDB, makes a projection of the given database in order to get the "tags" size, filters using the match projection and an $or operator over the tags and finally sorts the array over the "tags" size.

Hope this helps.

[ { item: "paper",tags: ["red", "blank", "plain","black"]},// mactch 3 "red","blank","black" { item: "journal",tags: ["blank", "red","blue","yellow"]},//macth 2 "blank", "red" { item: "notebook",tags: ["red", "pink","green"]},// match 1 "red" { item: "planner", tags: ["blank", "blue","gray"]}, // match 1 "blank" ] sort decrease — VietUngIT, Apr 24 '18 at 09:40
updated it once more: added projection (`$project`, `$match`, `$sort`). — Alexander, Apr 24 '18 at 10:10

Query search element array in mongo

1 Answers1