You have a lot of cars reporting traffic signs, and you want to have an app so that they can submit (longitude, latitude, sign_type) data packets to a central database, and also query (longitude, latitude, radius) and get a set of signs within of the specified point. We only want to return one sign of each type within the radius, however.
The app is coded with Mongo, Node.js, and Express.js. You can go to https://radiant-cliffs-86975.herokuapp.com/ to submit, and https://radiant-cliffs-86975.herokuapp.com/view to view. There's both a human-facing and JSON-based interface. You access the human-facing interface by filling out the form and clicking submit - there's basic error handling that prevents invalid data from entering the database (and the human form will refresh with the error messages). The JSON interface (by submitting a PUSH request from a program to the same URL) will lead to the same behavior (where invalid data won't be inserted).
You can 'search' for traffic signs again with the /view human interface, or by making POST requests to /view (with the additional tag type=json). Instead of returning HTML, the backend will return a JSON of found traffic signs. An example can be found in store_data.py and test.py.
store_data.py puts some test data into the database (you shouldn't have to run this) and test.py just runs a sample query and prints the result to the command line.
The data is stored and retrieved from MongoDB.