我如何 return json 被 {} 而不是 [] 包围 Node.js(express) returning 使用 knex 和 postgresql 的查询结果

Question

如果我对我的 node.js(EXPRESS) API curl http://127.0.0.1:3000/api/events/user/id/1 发出 curl 请求，我会得到以下结果：

[{"id":"1","name":"casamiento 1","description":"el casamiento del tio claudio","mode_id":1,"initial_date":"2016-05-28T22:14:57.000Z","end_date":"2016-05-28T22:14:58.000Z","state_id":1,"user_id":"1","location":"0101000020E61000000000000000805BC00000000000003E40"},{"id":"2","name":"casamiento 2","description":"el casamiento del tio claudio 2","mode_id":1,"initial_date":"2016-05-28T22:14:57.000Z","end_date":"2016-05-28T22:14:58.000Z","state_id":1,"user_id":"1","location":"0101000020E61000000000000000405BC00000000000003D40"},{"id":"3","name":"fiesta del sandwich de miga","description":"Nos juntamos a comer sandwiches de miga hasta reventar","mode_id":1,"initial_date":"2016-05-28T22:15:58.000Z","end_date":"2016-05-28T22:15:58.000Z","state_id":1,"user_id":"1","location":"0101000020E610000000000000000000000000000000804840"}]

我需要将输出用大括号括起来，例如：

 {{"id":"1","name":"casamiento 1","description":"el casamiento del tio claudio","mode_id":1,"initial_date":"2016-05-28T22:14:57.000Z","end_date":"2016-05-28T22:14:58.000Z","state_id":1,"user_id":"1","location":"0101000020E61000000000000000805BC00000000000003E40"},{"id":"2","name":"casamiento 2","description":"el casamiento del tio claudio 2","mode_id":1,"initial_date":"2016-05-28T22:14:57.000Z","end_date":"2016-05-28T22:14:58.000Z","state_id":1,"user_id":"1","location":"0101000020E61000000000000000405BC00000000000003D40"},{"id":"3","name":"fiesta del sandwich de miga","description":"Nos juntamos a comer sandwiches de miga hasta reventar","mode_id":1,"initial_date":"2016-05-28T22:15:58.000Z","end_date":"2016-05-28T22:15:58.000Z","state_id":1,"user_id":"1","location":"0101000020E610000000000000000000000000000000804840"}}

我的模型 "event" 文件是这样的，它对 knex 进行查询，然后 return 结果：

var express = require('express');
var router = express.Router();
var Promise = require("bluebird");
var connectionString = 'postgres://postgres:postgres@localhost:5432/flock';
var knex = require('knex')({
  client: 'pg',
  connection: connectionString,
  searchPath: 'knex,public'
});

//Get all events from a particular user
exports.getUserEvents=function(id_user){



    console.log("Retrieving data from id_user: "+id_user);

    var promise1 = Promise.try(function () {
    return knex('events')
      .select('*')
      .where('user_id', id_user);
     });

    var promise2=promise1.then(function (rows) { // this creates a new promise, and the promise created here is what gets returned to the caller
      console.log('Returning '+rows.length+' rows from the user with id '+id_user);
      return rows;

    });

    return promise2;
}

我的路由文件，调用了模型文件函数getUserEvents，是这样的：

var express = require('express');
var router = express.Router();
var Event=require('../models/event');


//get all events from a user

router.get('/user/id/:id_user', function(req, res, next) {

   var id_user= req.params.id_user;

   var promise = Event.getUserEvents(id_user);

    promise.then(function (result) {
     console.log('Sending response');
     return res.json(result);  //<---this line builds the JSON response
   });

   promise.catch(function (err) {


     return res.sendStatus(500); 

   });

});




module.exports = router

我的问题是，如何发送被 {} 包围的 json 对象列表，而不是像现在 returning 那样被 [] 包围？非常感谢

编辑：这解决了我的问题，最终格式为 {"rows":[{row1},{row2},etc]}

exports.getUserEvents=function(id_user){



    console.log("Retrieving data from id_user: "+id_user);

    var promise1 = Promise.try(function () {
    return knex('events')
      .select('*')
      .where('user_id', id_user);
     });

    var promise2=promise1.then(function (rows) { // this creates a new promise, and the promise created here is what gets returned to the caller
      console.log('Returning '+rows.length+' events from the user with id '+id_user);
      return {rows};//<----This solved the issue

    });

    return promise2; }

Answer 1

您的 api 请求是 return 对象数组

arrayOfObjects = [
    {objkey: objvalue},
    {objkey: objvalue}
]

您可以像这样将数组嵌套在对象中

newObj = {
    nestedarray: result
}

或者您可以return将对象作为单独的值

newObj = {
    1: result[0],
    2: result[1],
    3: result[2]
}

但是所有对象都需要一个键值对。

请注意，Javascript 中的数组实际上是一种特殊类型的对象，它仍然使用属性恰好是整数的名称，但经过优化以允许使用特殊方法。

所以在你的情况下：

var express = require('express');
var router = express.Router();
var Event=require('../models/event');


//get all events from a user

router.get('/user/id/:id_user', function(req, res, next) {

    var id_user= req.params.id_user;

    var promise = Event.getUserEvents(id_user);

    promise.then(function (result) {
    console.log('Sending response');

    // Option One
    var newObj = {
        nestedarray: result
    }

    // Option Two
    var newObj = {}
    response.forEach(function(elem, index) {
        newObj[index] = elem;
    });

    return res.json(newObj);  //<---this line builds the JSON response
});

   promise.catch(function (err) {

        return res.sendStatus(500); 

   });
});

请注意，在这两个选项中，您最终都不会得到所需的格式，这仅仅是因为这是不可能的，但任一选项都摆脱了数组语法。

Answer 2

假设您想单独处理每个对象，您可以使用：

for (i in result){
  console.log(result[i]);
}

那将 return，对于您提供的示例：

{"id":"1","name":"casamiento 1","description":"el casamiento del tio claudio","mode_id":1,"initial_date":"2016-05-28T22:14:57.000Z","end_date":"2016-05-28T22:14:58.000Z","state_id":1,"user_id":"1","location":"0101000020E61000000000000000805BC00000000000003E40"}
and
{"id":"2","name":"casamiento 2","description":"el casamiento del tio claudio 2","mode_id":1,"initial_date":"2016-05-28T22:14:57.000Z","end_date":"2016-05-28T22:14:58.000Z","state_id":1,"user_id":"1","location":"0101000020E61000000000000000405BC00000000000003D40"}
and
{"id":"3","name":"fiesta del sandwich de miga","description":"Nos juntamos a comer sandwiches de miga hasta reventar","mode_id":1,"initial_date":"2016-05-28T22:15:58.000Z","end_date":"2016-05-28T22:15:58.000Z","state_id":1,"user_id":"1","location":"0101000020E610000000000000000000000000000000804840"}

注意：{{stuff: 1}}，如您所提议的那样，是无效的JSON。

Answer 3

在 JSON 中，[] 方括号包围着数组。您的查询 return 是一个数组，而在您的行 return res.json(result) 中，结果变量是一个数组。将其设为 return 单个对象而不是数组，[] 将消失。如果您希望查询包含多个结果但仍然不需要数组，请将数组包装在另一个对象中，例如 {newResult: result} 和 return。

我如何 return json 被 {} 而不是 [] 包围 Node.js(express) returning 使用 knex 和 postgresql 的查询结果

How do I return a json surrounded by {} instead of [] on Node.js(express) returning a result of a query using knex and postgresql

json

node.js

express

knex.js