CODEWITHSUNDEEP
node.jsloopbackjs
kosta
kosta

Reputation: 4750

UnhandledPromiseRejectionWarning: TypeError: cb is not a function in loopback.js

I have the following code:

Orders.js

'use strict';

var OrderService = require('../services/OrderService');

module.exports = function(Orders) {

    var orderService = new OrderService(Orders);

    Orders.history = function(data, cb) {
        console.log("getting history");
        orderService.getHistory(data, cb)
            .catch(err => cb(err));
    };

    Orders.remoteMethod('history', {
        http: { verb: 'get', path: '/:token/history' },
        accepts: [
            { arg: "token", type: "string", required: true },
            { arg: "base_token", type: "string", required: true }
        ],
        returns: { type: 'object', root: true }
    });

};

Orderservice.js

function OrderService(Orders){
}

OrderService.prototype.getHistory = async function(token, baseToken,  callback){

    <some operation>

    callback(null, this.validatorService.finalize(buyResult));
}

When I hit this API, I get the following error

node:1996) UnhandledPromiseRejectionWarning: TypeError: cb is not a function
   at orderService.getHistory.catch.err (/usr/app/server/models/orders.js:12:18)
   at processTicksAndRejections (internal/process/next_tick.js:81:5)
 (node:1996) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
| (node:1996) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

I have similar code for other models and services, what am I missing?

Upvotes: 1

Views: 3875

Answers (1)

Peter Liapin
Peter Liapin

Reputation: 1275

When you define a remoteMethod the amount of arguments must always be equal to a number of arguments defined in the accepts property of your remoteMethod plus one which is cb. In your case there are two arguments defined in the accepts property, so the function should look like:

Orders.history = function(token, base_token, cb) {
    console.log("getting history");
    orderService.getHistory(token, cb)
        .catch(err => cb(err));
};

I would also recommend you to change your Orders.history to an async function and move away from callbacks completely. Loopback supports async functions/promises starting from version 2. The function can be defined as following:

Orders.history = async function(token, base_token) {
    console.log("getting history");
    return orderService.getHistory(token); // must return a promise
};

It may require a bit of code refactoring on your side but it allows you to write a cleaner code and you do not have to worry about the exceptions handling all the time (Loopback supports it out of the box for async functions).

Upvotes: 4

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