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Youngho Chaa cha cha

Using Regex Search for MongoDB Queries

mongodb, regex2 min read

As a developer, I often find myself in situations where I need to perform case-insensitive searches on data stored in MongoDB. This can be particularly useful when dealing with user information, such as names or emails. Fortunately, MongoDB provides a powerful feature called "regular expressions search" that can help us achieve this goal.

Here's the code snippet I wrote:

function getSearchFilter(queryStringParameters: APIGatewayProxyEventQueryStringParameters) {
const params = [
let filter = new Map<string, string | number | object>();
params.forEach((key) => {
if (queryStringParameters && queryStringParameters[key]) {
const value = queryStringParameters[key];
if (typeof value === 'number') {
filter.set(key, parseInt(queryStringParameters[key]));
} else {
filter.set(key, { $regex: new RegExp(queryStringParameters[key], 'i') });
return filter;

In this code snippet, we define a function getSearchFilter that takes an object queryStringParameters as input. This object contains the parameters passed in the query string of a request.

The function first defines an array params containing the keys we want to search for. Then, it creates an empty Map called filter.

Next, we loop through each key in the params array. If the queryStringParameters object contains a value for the current key, we check if the value is a number or not.

If the value is a number, we simply add it to the filter map with the corresponding key.

However, if the value is not a number, we create a regular expression object using the new RegExp() constructor. We pass the value from queryStringParameters as the first argument and the 'i' flag as the second argument. The 'i' flag makes the regular expression case-insensitive.

We then add this regular expression object to the filter map, using the $regex operator provided by MongoDB. This tells MongoDB to perform a regular expression search for the given key and value.

Finally, we return the filter map, which can be used in a MongoDB query to perform a case-insensitive search.

By leveraging regular expressions in this way, I was able to easily search for user names and emails, regardless of their capitalization. This approach can be applied to various scenarios where case-insensitive searches are required, making it a valuable tool in a developer's arsenal.

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