Prevent Duplicate Submissions in a Web Project

Preventing duplicate submissions is a common function in a web project. In this post, I will cover the principle of the implementation of preventing duplicate submissions.

The process

1. Create a Filter or Interceptor in the web project to check whether the request is a duplicate submission.
2. Get the request information and determine whether it is a duplicate submission.
   • If it’s a duplicate submission, return an error message to the client.
   • If not, save the request information to cache (Redis) and set expiration time to 2-3 seconds.

Filter or Interceptor is a common component in a web framework of the web backend, which can check the request data before handling the request.

Details

How to save the request information to Redis

• Type: string
• Key: duplicate_submit:{user_id}:{request_uri}:{request_method}
• Value: {request_query_string} + {request_body or filename}
• Expiration time: 2-3 seconds

How to determine whether the request is a duplicate submission

1. Get the userId of the current login user.
2. Get requestURI, requestMethod, requestQueryString, requestBody from the Request.
3. Get previous request data: get the value of the key duplicate_submit:{user_id}:{request_uri}:{request_method} from Redis.
4. Compare current request data with previous request data.