Question

有一个奇怪的问题。一直在寻找答案但没有任何结果。我正在做一个节点api教程，当我执行任何GET请求时它从我的终端中的mongoDB数据库返回JSON但是在我的浏览器或邮递员中我得不到任何回复，只有在终端我才得到任何响应。当我在邮递员中尝试POST时，它说它无法连接到后端。

这是我的代码：

var http = require('http');
var url = require('url');
var database = require('./database');


// Generic find methods (GET)

function findAllResources(resourceName, req, res) {
  database.find('OrderBase', resourceName, {}, function (err, resources) {
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end(JSON.stringify(resources));
  });
};

var findResourceById = function (resourceName, id, req, res) {
  database.find('OrderBase', resourceName, {'_id': id}, function (err, resource) {
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end(JSON.stringify(resource));
  });
};

// Product methods

var findAllProducts = function (req, res) {
  findAllResources('Products', req, res);
};

var findProductById = function (id, req, res) {
  findResourceById('Products', id, req, res);
};

// Generic insert/update methods (POST, PUT)

var insertResource = function (resourceName, resource, req, res) {
  database.insert('OrderBase', resourceName, resource, function (err, resource) {
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end(JSON.stringify(resource));
  });
};

// Product methods

var insertProduct = function (product, req, res) {
  insertResource('OrderBase', 'Product', product, function (err, result) {
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end(JSON.stringify(result));
  });
};


var server = http.createServer(function (req, res) {

  // Break down the incoming URL into its components
  var parsedURL = url.parse(req.url, true);

  // determine a response based on the URL
  switch (parsedURL.pathname) {
    case '/api/products':
    if (req.method === 'GET') {
      // Find and return the product with the given id
      if (parsedURL.query.id) {
        findProductById(id, req, res)
      }
      // There is no id specified, return all products
      else {
        findAllProducts(req, res);
      }
    }
    else if (req.method === 'POST') {

      //Extract the data stored in the POST body
      var body = '';
      req.on('data', function (dataChunk) {
        body += dataChunk;
      });
      req.on('end', function () {
        // Done pulling data from the POST body.
        // Turn it into JSON and proceed to store it in the database.
        var postJSON = JSON.parse(body);
        insertProduct(postJSON, req, res);
      });
    }
    break;
    default:
    res.end('You shall not pass!');
  }
});
server.listen(8080);

console.log('Up and running, ready for action!');

Answer 1

您有几个回调，err作为第一个参数，但您没有处理任何潜在的错误。这意味着如果出现问题，你就不会抓住它并返回错误。我不知道这是否与它有关，但作为一种做法（甚至不是“最佳”，而是一般做法）而不是这样做

function (err, resource) {
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end(JSON.stringify(resource));
  }

这样做

function (err, resource) {
  if(err){
    // do something to warn the client and stop here
  }
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end(JSON.stringify(resource));
  }

试一试，看看在尝试输出答案之前是否确实遇到了错误。

Answer 2

https://nodejs.org/api/http.html#http_response_end_data_encoding_callback

响应结束方法不将数据发送到响应套接字。也许你改变它

res.writeHead(200, {'Content-Type': 'application/json'});
res.end(JSON.stringify(resource));

res.writeHead(200, {'Content-Type': 'application/json'});
res.write(JSON.stringify(resource));
res.end();

如果你想让socket关闭做某事，你可以回调结束。

res.end(#logHandle());

Answer 3

var MongoClient = require('mongodb').MongoClient;

var assert = require('assert');


var connect = function  (databaseName, callback) {
var url = 'mongodb://localhost:27017/' + databaseName;

MongoClient.connect(url, function  (error, database) {
    assert.equal(null, error);

    console.log("Successfully connected to MongoDB instance!");

    callback(database);
})
};


exports.find = function  (databaseName, collectioName, query, callback) {
connect(databaseName, function  (database) {
    var collection = database.collection(collectioName);

    collection.find(query).toArray(
        function  (err, documents) {
            assert.equal(err, null);

            console.log('MongoDB returned the following documents:');
            console.dir(JSON.parse(JSON.stringify(documents)));
            //console.dir(documents);
            callback(null, documents);
        }
    )

    database.close();
})
};

我认为我们正在阅读相同的教程，这是我的解决方案＆＃39; database.js＆＃39;，对我有用。

Node.js API在终端中返回JSON但在浏览器中不返回

3 个答案: