Não consigo acessar o banco depois de ter isolado a função

Tá o seguinte erro:

TypeError: Cannot read property 'query' of undefined
    at C:\Users\pedro\casadocodigo\app\routes\produtos.js:8:15
    at Layer.handle [as handle_request] (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\route.js:137:13)
    at Route.dispatch (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\pedro\casadocodigo\node_modules\express\lib\router\index.js:281:22
    at Function.process_params (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\index.js:335:12)
    at next (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\index.js:275:10)
    at expressInit (C:\Users\pedro\casadocodigo\node_modules\express\lib\middleware\init.js:40:5)
    at Layer.handle [as handle_request] (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\layer.js:95:5)

eis o código:

TypeError: Cannot read property 'query' of undefined
    at C:\Users\pedro\casadocodigo\app\routes\produtos.js:8:15
    at Layer.handle [as handle_request] (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\route.js:137:13)
    at Route.dispatch (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\pedro\casadocodigo\node_modules\express\lib\router\index.js:281:22
    at Function.process_params (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\index.js:335:12)
    at next (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\index.js:275:10)
    at expressInit (C:\Users\pedro\casadocodigo\node_modules\express\lib\middleware\init.js:40:5)
    at Layer.handle [as handle_request] (C:\Users\pedro\casadocodigo\node_modules\express\lib\router\layer.js:95:5)

e a exportação do módulo:

var mysql = require('mysql');

module.exports = function(){

      var connection = mysql.createConnection({

            host: "localhost",
            user:"root",
            password: "8016",
            database:"casadocodigo_nodejs",

        });

};