CODEWITHSUNDEEP
pythonregexmongodbpymongo
sudeepgupta90
sudeepgupta90

Reputation: 795

Creating $elemMatch query with multiple $regex clauses in python and mongo

I am implementing this tutorial How to Speed-Up MongoDB Regex Queries by a Factor of up-to 10 and I am using the query specified at the end

db.movies.find({
$and:[{
    $text: {
        $search: "Moss Carrie-Anne"
    }},{
    cast: {
        $elemMatch: {$regex: /Moss/, $regex: /Carrie-Anne/}}
    }]}
);

The problem where I am stuck with is how do I generate the sub-query

$elemMatch: {$regex: /Moss/, $regex: /Carrie-Anne/}

programmatically with python

My code so far

def regexGen(s):
  d={}
  for word in s.split(" "):
    d["$regex"]= "/"+word+"/"  # this will of course save only the last value into the dict

  return (d)


query= {
    "$and":[{
        "$text": {
            "$search": "Moss Carrie-Anne"
        }},{
        "cast": {
            "$elemMatch": regexGen("Moss Carrie-Anne")}
        }
    ]
}

print (query)

#actual
# {'$and': [{'$text': {'$search': 'Moss Carrie-Anne'}}, {'cast': {'$elemMatch': {'$regex': '/Carrie-Anne/'}}}]}

#expected
# {'$and': [{'$text': {'$search': 'Moss Carrie-Anne'}}, {'cast': {'$elemMatch': {'$regex': '/Carrie-Anne/'}, {'$regex': '/Moss/'} }}]}

I am obviously missing something here, but not able to figure out

Upvotes: 2

Views: 397

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627292

You may build a dynamic regex based on alternation:

{ "$regex" : "|".join([re.escape(word) for word in s.split()]) }

See the Python demo:

import re
s = "Moss Carrie-Anne"
print({ "$regex" : "|".join([re.escape(word) for word in s.split()]) })
# => {'$regex': 'Moss|Carrie\-Anne'}

Note that Moss|Carrie\-Anne will match either Moss or Carrie-Anne. re.escape will be helpful if you have (, + and other regex special chars in your literal input.

Upvotes: 1

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