How to query postgres on optional params?

Question

I am setting up an REST service and I am using postgres as the data store. I want to know how to set up a postgres query to use optional parameters. ie:

SELECT * from users  where hair_color = $1  and eye_color = $2 

Where $1 and $2 come from the request: [req.body.hair_color, req.body.eye_color]

What if the user didn't pass in eye_color and in that case I wanted all eye colors. I assume that I don't have to make a bunch of if/else statements here. What is the concise way of creating this query?

Answer 1

Here I've made both hair_color and eye_color optional. (Pass your language's equivalent of NULL).

SELECT * from users where    ($1 is null or hair_color = $1) and    ($2 is null or eye_color = $2);