MongoDB find fields which are substring of a query text - mongodb

Question

I have been looking for a way to do that but couldn't find any.
I'd like to know if is possible to, from a given query, return all fields that are contained in that query.
For example my dataset is as follows:
{ "_id" : ObjectId("5d5c2b4cc1f74ace3a48a072"), "id" : 0, "term" : "shorts" }
{ "_id" : ObjectId("5d5c2b4cc1f74ace3a48a072"), "id" : 0, "term" : "jacket" }
{ "_id" : ObjectId("5d5c2b4cc1f74ace3a48a072"), "id" : 1, "term" : "yellow jacket" }
{ "_id" : ObjectId("5d5c2b56c1f74ace3a48a073"), "id" : 2, "term" : "blue jacket" }
{ "_id" : ObjectId("5d5c2b65c1f74ace3a48a074"), "id" : 3, "term" : "blue shorts" }
{ "_id" : ObjectId("5d5c2b71c1f74ace3a48a075"), "id" : 4, "term" : "red shorts" }
And now, given a text like: "I really love blue shorts", the return should be only:
{ "_id" : ObjectId("5d5c2b71c1f74ace3a48a075"), "id" : 3, "term" : "blue shorts" }
{ "_id" : ObjectId("5d5c2b4cc1f74ace3a48a072"), "id" : 0, "term" : "shorts" }
It's something like query.contains(field)

Answer 1

Using $where is generally discouraged in mongodb because of
javascript execution in the query system and can be slow.
You can try this out if the dataset is not very large. Its like doing reverse regex for the field value contained in the query.
db.collection.find({$where: "\""I really love blue shorts\".match(this.term)"});
Which outputs:
{ "_id" : ObjectId("5d5c32c1236f19364a8aad4d"), "id" : 0, "term" : "shorts"}
{ "_id" : ObjectId("5d5c32c1236f19364a8aad51"), "id" : 3, "term" : "blue shorts"}
NOTE: This takes the assumption that term is defined in the documents, else you can use a javascript function for the $where value to deal with edge cases such as not defined fields, etc.
{ $where: function() { return /* after edge cases dealt with*/ }

Answer 2

The following query can get us the expected output:
db.collection.aggregate([
{
$addFields:{
"searchString":"I really love blue shorts"
}
},
{
$match:{
$expr:{
$gt:[
{
$indexOfBytes:["$searchString","$term"]
},
-1
]
}
}
},
{
$project:{
"searchString":0
}
}
]).pretty()
Data set:
{
"_id" : ObjectId("5d5c2b4cc1f74ace3a48a070"),
"id" : 0,
"term" : "shorts"
}
{
"_id" : ObjectId("5d5c2b4cc1f74ace3a48a071"),
"id" : 0,
"term" : "jacket"
}
{
"_id" : ObjectId("5d5c2b4cc1f74ace3a48a072"),
"id" : 1,
"term" : "yellow jacket"
}
{
"_id" : ObjectId("5d5c2b56c1f74ace3a48a073"),
"id" : 2,
"term" : "blue jacket"
}
{
"_id" : ObjectId("5d5c2b65c1f74ace3a48a074"),
"id" : 3,
"term" : "blue shorts"
}
{
"_id" : ObjectId("5d5c2b71c1f74ace3a48a075"),
"id" : 4,
"term" : "red shorts"
}
Output:
{
"_id" : ObjectId("5d5c2b4cc1f74ace3a48a070"),
"id" : 0,
"term" : "shorts"
}
{
"_id" : ObjectId("5d5c2b65c1f74ace3a48a074"),
"id" : 3,
"term" : "blue shorts"
}