Question

我有以下代码：

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));
}

点击此API时，出现以下错误

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.

对于其他模型和服务，我也有类似的代码，我缺少什么？

Answer 1

定义remoteMethod时，参数数量必须始终等于remoteMethod的accepts属性中定义的参数数量加上cb。在您的情况下，accepts属性中定义了两个参数，因此该函数应类似于：

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

我还建议您将Orders.history更改为异步函数，并完全摆脱回调。 Loopback supports async functions/promises从版本2开始。该函数可以定义如下：

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

这可能需要您进行一些代码重构，但是它使您可以编写更简洁的代码，而不必担心所有时间都在处理异常（Loopback为异步功能提供了开箱即用的支持）。

UnhandledPromiseRejectionWarning：TypeError：cb不是loopback.js中的函数

1 个答案: