You're missing my point because you're focused on the database query. I'm talking about the web application framework. If this was written in Asp.Net, for example, the password field would be declared as a string and the data binding code within Asp.Net would validate that the field was in fact a string as part of instantiating a model for the strongly typed request body. If someone passed in an object for that field your code for the endpoint, including all of the database interaction, would never be called because the framework would automatically return a 400 response when data binding failed.