Performing regex Queries with PyMongo?

PyMongo is a Python distribution containing tools for working with MongoDB. To perform regex queries with PyMongo, you use the $regex operator to match documents where field values match a specified regular expression pattern.

Syntax

db.collection.find({
    "fieldName": {
        "$regex": "pattern",
        "$options": "flags"
    }
})

Sample Data

Let us create a collection with sample documents ?

db.performRegex.insertMany([
    {
        "ClientName": "Larry",
        "ClientFolderInformation": [
            "Folder 1", "Folder 2", "Folder 3", "Folder 4", "Folder 5"
        ],
        "MainFolderLocation": "/MainFolder/Details/ClientFolder"
    },
    {
        "ClientName": "Larry",
        "ClientFolderInformation": [
            "ClientFolder 1", "ClientFolder 2", "ClientFolder 3", "ClientFolder 4", "ClientFolder 5"
        ],
        "MainFolderLocation": "/MainFolder/Details/ClientFolder"
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5c8a8b186cea1f28b7aa07f2"),
        ObjectId("5c8a8b1d6cea1f28b7aa07f3")
    ]
}

Case 1: Find Array Elements Starting with "ClientFolder"

Find documents where array elements start with "ClientFolder" ?

db.performRegex.find({
    "ClientFolderInformation": {
        "$regex": "^ClientFolder"
    }
}).pretty();

{
    "_id": ObjectId("5c8a8b1d6cea1f28b7aa07f3"),
    "ClientName": "Larry",
    "ClientFolderInformation": [
        "ClientFolder 1",
        "ClientFolder 2",
        "ClientFolder 3",
        "ClientFolder 4",
        "ClientFolder 5"
    ],
    "MainFolderLocation": "/MainFolder/Details/ClientFolder"
}

Case 2: Find Array Elements Starting with "Folder"

Find documents where array elements start with "Folder" ?

db.performRegex.find({
    "ClientFolderInformation": {
        "$regex": "^Folder"
    }
}).pretty();

{
    "_id": ObjectId("5c8a8b186cea1f28b7aa07f2"),
    "ClientName": "Larry",
    "ClientFolderInformation": [
        "Folder 1",
        "Folder 2",
        "Folder 3",
        "Folder 4",
        "Folder 5"
    ],
    "MainFolderLocation": "/MainFolder/Details/ClientFolder"
}

PyMongo Implementation

Here's how to perform the same regex queries using PyMongo in Python ?

from pymongo import MongoClient
import re

client = MongoClient('mongodb://localhost:27017/')
db = client['your_database']
collection = db['performRegex']

# Method 1: Using $regex operator
result = collection.find({
    "ClientFolderInformation": {
        "$regex": "^ClientFolder"
    }
})

# Method 2: Using Python's re module
result = collection.find({
    "ClientFolderInformation": re.compile("^ClientFolder")
})

Conclusion

The $regex operator enables pattern matching in MongoDB queries. Use ^ for start-of-string matching and combine with PyMongo for powerful text search capabilities in Python applications.