Modifying graphql query variable using express-gateway - express

Question

I'm trying to modify a graphql query variable using express-gateway.
The code on the gateway is as below,
const axios = require("axios");
const jsonParser = require("express").json();
const { PassThrough } = require("stream");
module.exports = {
name: 'gql-transform',
schema: {
... // removed for brevity sakes
},
policy: (actionParams) => {
return (req, res, next) => {
req.egContext.requestStream = new PassThrough();
req.pipe(req.egContext.requestStream);
return jsonParser(req, res, () => {
req.body = JSON.stringify({
...req.body,
variables: {
...req.body.variables,
clientID: '1234'
}
});
console.log(req.body); // "clientID": "1234" is logged in the body.variables successfully here
return next();
});
};
}
};
Now, when I hit the request from POSTMAN, the request goes through and returns a 200OK only when I include clientID, otherwise, it throws as error
"message": "Variable "$clientID" of required type "ID!" was not provided."
Any idea what could be going wrong here?

Answer 1

The only way I could get this working was by using node-fetch and then making a fetch request to the graphql-sever from my middleware instead of doing a return next() and following the middleware chain.
My setup is something like the following,
Client (vue.js w/ apollo-client) ---> Gateway (express-gateway) ---> Graphql (apollo-server) ---> Backend REST API (*)
When my client makes a graphql request to my gateway, I've modified my middleware to do the following (as opposed to what's in the question),
const jsonParser = require("express").json();
const fetch = require('node-fetch');
module.exports = {
name: 'gql-transform',
schema: {
... // removed for brevity sakes
},
policy: () => {
return (req, res) => {
jsonParser(req, res, async () => {
try {
const response = await fetch(`${host}/graphql`, {...}) // removed config from fetch for brevity
res.send(response);
} catch (error) {
res.send({ error });
}
});
};
}
};