Find n words inside a Mongodb document

Question

Im trying to create a query that finds a collection of documents that match a criteria, a simple search system. The problem is that the assets inside the collection are like this:

{ 
 fristName: "foo",
 lastName: "bar",
 description: "mega foo",
},
{ 
 fristName: "Lorem",
 lastName: "Ipsum",
 description: "mega Lorem bla bla",
},

If the user wants all the assets that contains the word bar i should show the asset 1 of the example, and that is not a problem, but what if he inputs foo mega?, in that case i need also to show the asset 1 because foo and mega are present in asset 1 (both of them), if he searchs only mega, the output is asset 1 and 2, and if he search mega ipsum, the result is asset 2. I have no idea how to write this query in mongoDb.

Answer 1

Mongodb 2.6+ has built in support for text searches using the $text operator. Here's how to use it.

1. Build an text index on the desired searchable fields. Note: For MongoDB 2.6 you can only have 1 text index on a collection.

   Create text index on one field

   db.test.ensureIndex({ 
       "field1" : "text"
    }, { name : "Field1TextIndex"});
   

   Create text index on two fields

   db.test.ensureIndex({ 
       "field1" : "text",
       "field2" : "text"
    }, { name : "Field12TextIndex"});
   

   Create text index for any string field

   db.test.ensureIndex({ 
       "$**" : "text" 
   }, { name : "AllTextIndex"});
   

2. Query the collection using the $text operator.

   Here's the format for $text

   { $text: { $search: <string of keywords>, $language: <string> } }
   

Example code

Setup

use test;
var createPerson = function(f,l,d){
    return { firstName : f, lastName: l, description : d};
};
db.test.remove({});
db.test.insert(createPerson("Ben", "Dover", "Real Estate Agent"));
db.test.insert(createPerson("James", "Bond", "secret agent, ben's friend"));

Creating an text index on all string fields in a document.

db.test.ensureIndex({ "$**" : "text" }, { name : "AllTextIndex"});

Query all fields for keywords

Searching for ben

db.test.find({  
    $text : {
        $search : "ben"
    }
});

Output

{ "_id" : "...", "firstName" : "James", "lastName" : "Bond", "description" : "secret agent, ben's friend" }
{ "_id" : "...", "firstName" : "Ben", "lastName" : "Dover", "description" : "Real Estate Agent" }

The search for "ben" returned both documents since one had Ben as the firstName, and the other had ben's in the description field.

Querying for real friend produces the same result.

db.test.find({  
    $text : {
        $search : "real friend"
    }
});

More info here:

• Doc: Create a text Index on multiple fields
• Video: Demo of MongoDB Text Search and Hashed Shard Keys
• Doc: $text operator

Answer 2

Possible solution is to search via keywords. I mean you have to add keywords field to each object, like:

{ 
 fristName: "foo",
 lastName: "bar",
 description: "mega foo",
 keywords: ["foo", "bar", "mega"]
},
{ 
 fristName: "Lorem",
 lastName: "Ipsum",
 description: "mega Lorem bla bla",
 keywords: ["mega", "Lorem", "Ipsum", "bla"]
},

The you have to split request string to keywords, e.g.

"foo mega"

will be converted into

["foo", "mega"]

and then you can search objects by keywords field.