Question

我试图绕过承诺，但到目前为止，我似乎无法得到简单的例子。这是一个从服务器请求JSON的代码：

module.exports = function (app, options) {
var promise = require('bluebird');
var request = require('request-json');

var module = {
    url: options.url,
    httpClient: promise.promisifyAll(request.createClient(options.url))
};

module.getSample = function() {
    return this.httpClient.getAsync('sample/')
        .then(function(error, response, body) {
            console.log(body);
        })
        .catch(function(e) {
            console.log('error');
            console.log(e);
        });
};

return module;

};

但是当我这样称呼时：

var backendClient = require('./utils/backendClient.js')(app, {
    url: 'http://localhost:8080/'
});

backendClient.getSample()

在运行时我收到一条错误，说“＆＃39; [SyntaxError：Unexpected token o]＆＃39;。没有承诺的版本工作正常。我错过了什么？

Answer 1

module.getSample = function() {
    return this.httpClient.getAsync('sample/')
        .then(function(error, response, body) {
            // not sure what Promise library you are using, but in the Promise/A+ spec, the function in then only receives a single argument, the resolved value of the Promise
            console.log(body);
            // this returns equivalent to Promise.resolve(undefined);
            // you really want to return something meaningful here
        })
        .catch(function(e) {
            console.log('error');
            console.log(e);
            // this also returns equivalent to Promise.resolve(undefined);
            // to propagate the "error" condition, you want to either throw e, or return Promise.reject(something here);
        });
};

这将始终返回一个完整的承诺，其中 undefined 为值，绝不会被拒绝。上面评论的其他错误

request-json与bluebird承诺的奇怪行为

1 个答案: