删除嵌套的承诺

我不熟悉NodeJS中的使用请求和承诺的承诺和编写networking代码。

我想删除这些嵌套的承诺，并链接他们，但我不知道我会怎么做/是否是正确的路要走。

exports.viewFile = function(req, res) { var fileId = req.params.id; boxContentRequest('files/' + fileId + '/content', req.user.box.accessToken) .then(function(response) { boxViewerRequest('documents', {url: response.request.href}, 'POST') .then(function(response) { boxViewerRequest('sessions', {document_id: response.body.id}, 'POST') .then(function(response) { console.log(response); }); }); }); }; 

这是请求代码：

 var baseContentURL = 'https://api.box.com/2.0/'; var baseViewerURL = 'https://view-api.box.com/1/'; function boxContentRequest(url, accessToken) { return new Promise(function (resolve, reject) { var options = { url: baseContentURL + url, headers: { Authorization: 'Bearer ' + accessToken, } }; request(options, function (err, res) { if (err) { return reject(err); } else if (res.statusCode !== 200) { err = new Error("Unexpected status code: " + res.statusCode); err.res = res; return reject(err); } resolve(res); }); }); } function boxViewerRequest(url, body, method) { return new Promise(function (resolve, reject) { var options = { method: method, url: baseViewerURL + url, headers: { Authorization: 'Token ' + config.box.viewerApiKey }, json: body }; request(options, function (err, res, body) { if (err) { return reject(err); } else if (res.statusCode !== 200 && res.statusCode !== 201 && res.statusCode !== 202) { err = new Error("Unexpected status code: " + res.statusCode); err.res = res; return reject(err); } resolve(res, body); }); }); } 

任何有识之士将不胜感激。

Answer 1

从每一个callback中，你都需要返回新的承诺：

 exports.viewFile = function(req, res) { var fileId = req.params.id; boxContentRequest('files/' + fileId + '/content', req.user.box.accessToken) .then(function(response) { return boxViewerRequest('documents', {url: response.request.href}, 'POST'); }) .then(function(response) { return boxViewerRequest('sessions', {document_id: response.body.id}, 'POST'); }) .then(function(response) { console.log(response); }); }; 

然后由.then()调用返回的承诺将使用来自“内部”承诺的值来解决，以便您轻松链接它们。

通用模式：

 somePromise.then(function(r1) { return nextPromise.then(function(r2) { return anyValue; }); }) // resolves with anyValue || \||/ \/ somePromise.then(function(r1) { return nextPromise; }).then(function(r2) { return anyValue; }) // resolves with anyValue as well