Implement custom logic after the graphql query has been parsed - node.js

Question

Is there a way to implement custom logic right after the graphql query has been parsed, but before any of the resolvers have executed?
Given this query schema
type Query {
products(...): ProductConnection!
productByHandle(handle: String!): Product
}
How can I accomplish the task of logging the info object for the products and productByHandle queries, before their resolvers have had a chance to execute?
I'm basically looking to "hook up" to an imaginary event like query:parsed, but it doesn't appear to exist. I'm using the express-graphql package.

Answer 1

Props to #xadm for figuring this out.
express-graphql package accepts a custom execute function, which is the function that gets called after the query has been parsed. Its return value is what gets returned from the /graphql endpoint.
import { graphHTTP } from 'express-graphql'
import { execute } from 'graphql'
app.use('/graphql', graphHTTP((req, res) => {
return {
...,
async customExecuteFn(ExecutionArgs) {
// The `info` object is available on ExecutionArgs
// { data: {...}, errors: [...] }
const result = await execute(ExecutionArgs)
return result
}
}
}))
I will still leave this here, as it might be useful for something more specific, but you should probably use the code above.
// This returns an object, whose keys are the query names and the values are the definitions ( name, resolve etc )
const queryFields = graphqlSchema.getQueryType().getFields()
// They can then be iterated, and the original `resolve` method can be monkey-patched
for (const queryName in queryFields) {
const queryInfo = queryFields[queryName]
// Grab a copy of the original method
const originalResolve = queryInfo.resolve
// Overwrite the original `resolve` method
queryInfo.resolve = function patchedResolve(src, args, context, info) {
// Your custom logic goes here
console.log(info);
// Call the original `resolve` method, preserving the context and
// passing in the arguments
return originalResolve.apply(this, arguments)
}
}