Here is a simple express router, I want to give it query params and search the DB for them.
so, if the URL is like this api?x=value1 the app should query the DB for { x:value1 }
if the URL is api?x=value1&y=value2 the app should query the DB for { x:value1, y:value2 }
Since I don't know the number of params in advance, I have created an empty object and appended it with the params if existed.
if there are no params I want to retrieve all documents in DB.
.get(function (req, res){
let update_issue= {}; /*empty object*/
if(req.query.issue_title){update_issue["issue_title"] = req.query.issue_title}
if(req.query.issue_text){update_issue["issue_text"] = req.query.issue_text}
if(req.query.created_by){ update_issue["created_by"] = req.query.created_by }
/*append object if param exists*/
if(Object.keys(update_issue).length !== 0 ){ /*check if that object is not empty*/
db.collection('issues').find(update_issue, (err, data)=>{
res.json(data);
})
}
db.collection('issues').find().toArray((err, data)=>{
res.send(data);
})
this solution keeps giving me TypeError: Converting circular structure to JSON.
I understand that the object is in the form { x : "value" } and it should be JSON object like this { "x": "value" }
I tried flatted, JSON-stringify-safe still the same problem.
can you give me a solution to this problem, or an alternative way to continue the work.
I have solved the problem using node package called Api query params.
here is my code:
var aqp = require('api-query-params');
.get(function (req, res){
let update_issue= aqp(req.query);
if(Object.keys(update_issue).length !== 0 ){ /*check if that object is not empty*/
db.collection('issues').find(update_issue, (err, data)=>{
res.json(data);
})
}
db.collection('issues').find().toArray((err, data)=>{
res.send(data);
})
here is the package : https://www.npmjs.com/package/api-query-params
Related
var express = require("express")
let PersonModel = require('./PersonModel')
let mongodbConnected=require('./MongodbConnect')
var app =express()
var bodyparser=require("body-parser")
const { format } = require("path")
const { count } = require("console")
const { countDocuments } = require("./PersonModel")
const { exec } = require("child_process")
const { get } = require("http")
const { ALL } = require("dns")
app.use(bodyparser.urlencoded({extended:false}))
app.get('/',function(req,res){
res.sendFile('Person.html', { root: __dirname });
})
app.get('/about',function (req,res){
res.send("This is a simple express application using mongodb express html and mongoose")
PersonModel.countDocuments().exec()
.then(count=>{
console.log("Total documents Count before addition :", count)
}) .catch(err => {
console.error(err)
})
})
app.post('/add', function(req,res){
Pname=req.body.empname
console.log('Pname',Pname)
PAge=req.body.Age
PGender=req.body.gender
PSalary=req.body.salary
const doc1 = new PersonModel(
{
name:Pname,age:33,Gender:PGender,Salary
:PSalary}
)
doc1.save(function(err,doc){
if (err) return console.error(err)
else
console.log("doc is added ",doc)
//res.send("Record is added"+doc)
res.send({
'status':true,
'Status_Code':200,
'requested at': req.localtime,
'requrl':req.url,
'request Method':req.method,
'RecordAdded':doc});
}
)
})
app.post('/findperson', function(req,res){
PAge=req.body.Age
console.log("Page",PAge)
PersonModel.find({age:{$gte:PAge}})
// find all users
.sort({Salary: 1}) // sort ascending by firstName
.select('name Salary age')// Name and salary only
.limit(10) // limit to 10 items
.exec() // execute the query
.then(docs => {
console.log("Retrieving records ",docs)
res.send(docs)
})
.catch(err => {
console.error(err)})
})
app.post('/delete', function(req,res){
Pgender=req.body.gender
PersonModel.findOneAndDelete({Gender:Pgender }
).exec()
.then(docs=>{
console.log("Deleted")
console.log(docs); // Success
}).catch(function(error){
console.log(error); // Failure
});
})
app.post('/update', function(req,res){
Pname=req.body.empname
Pnewname=req.body.newname
PnewAge=req.body.newage
PersonModel.findOneAndUpdate({ name: Pname },{"$set":{name:Pnewname,age:PnewAge}}).exec()
.then(docs=>{
console.log("Update for what i get is ",Pname
,Pnewname,PnewAge)
console.log(docs); // Success
}).catch(function(error){
console.log(error); // Failure
});
})
var docnum=PersonModel.countDocuments(ALL)
app.post('/count', function(req, res){
res.send('Total number of documents: ', docnum)
})
app.listen(5000,function(){
console.log("Server is running on the port 5000")
})
Hello.
First time posting on stackoverflow, dont know what kind of information to post, please let me know.
Im trying to make a page (/count) to simply display the number of documents. I've tried different code but nothing is working. This error keeps coming up "TypeError: Converting circular structure to JSON".
This is school work so the code is given to me by a teacher and I have to add a POST method to add a page that displays total number of documents.
Any ideas?
Thanks.
Circular structure is not about mongo but how JS read the JSON object.
For example, if you have this object:
var object = {
propA: "propA",
propB: object
}
When JS try to deserialize JSON object, will handle that: One object contains the object that contain again the object and again and again... that is a circular dependence.
Not only with one object itself, aslo with more objects:
var objectA = {
propA: objectB
}
var objectB = {
propA: objectA
}
Is the same case.
Using node.js you can use util.inspecet() which automatically show [Circular] when a circular dependence is found.
You can use like this:
var util = require('util')
console.log(util.inspect(objectA))
I am trying to convert a table to JSON, to search for data easily, the URL is: http://www.tppcrpg.net/rarity.html
I found this package:
https://www.npmjs.com/package/tabletojson
I tried to use it like:
'use strict';
const tabletojson = require('tabletojson');
tabletojson.convertUrl(
'http://www.tppcrpg.net/rarity.html',
{ useFirstRowForHeadings: true },
function(tablesAsJson) {
console.log(tablesAsJson[1]);
}
);
However it returns undefined in the console, are there any alternative options or am I using the package wrong?
Hey you are actually getting data, change the console.log
Your output have total one array only but you are putting tablesAsJson[1] in console, but array index starts with [0].
'use strict';
const tabletojson = require('tabletojson');
tabletojson.convertUrl(
'http://www.tppcrpg.net/rarity.html',
function(tablesAsJson) {
console.log(tablesAsJson[0]);
}
);
For better looking code:
const url = 'http://www.tppcrpg.net/rarity.html';
tabletojson.convertUrl(url)
.then((data) => {
console.log(data[0]);
})
.catch((err) => {
console.log('err', err);
}); // to catch error
Basically, I am setting up a web server via Node.js and Express (I am a beginner at this) to retrieve data by reading a JSON file.
For example, this is my data.json file:
[{
"color": "black",
"category": "hue",
"type": "primary"
},
{
"color": "red",
"category": "hue",
"type": "primary"
}
]
I am trying to retrieve all of the colors by implementing this code for it to display on localhost:
router.get('/colors', function (req, res) {
fs.readFile(__dirname + '/data.json', 'utf8', function (err, data) {
data = JSON.parse(data);
res.json(data); //this displays all of the contents of data.json
})
});
router.get('/colors:name', function (req, res) {
fs.readFile(__dirname + '/data.json', 'utf8', function (err, data) {
data = JSON.parse(data);
for (var i = 0; i < data.length; i++) {
res.json(data[i][1]); //trying to display the values of color
}
})
});
How do I go about doing this?
What you are trying to do is actually pretty simple once you break it into smaller problems. Here is one way to break it down:
Load your JSON data into memory for use by your API.
Define an API route which extracts only the colours from your JSON data and sends them to the client as a JSON.
var data = [];
try {
data = JSON.parse(fs.readFileSync('/path/to/json'));
} catch (e) {
// Handle JSON parse error or file not exists error etc
data = [{
"color": "black",
"category": "hue",
"type": "primary"
},
{
"color": "red",
"category": "hue",
"type": "primary"
}
]
}
router.get('/colors', function (req, res, next) {
var colors = data.map(function (item) {
return item.color
}); // This will look look like: ["black","red"]
res.json(colors); // Send your array as a JSON array to the client calling this API
})
Some improvements in this method:
The file is read only once synchronously when the application is started and the data is cached in memory for future use.
Using Array.prototype.map Docs to extract an array of colors from the object.
Note:
You can structure the array of colors however you like and send it down as a JSON in that structure.
Examples:
var colors = data.map(function(item){return {color:item.color};}); // [{"color":"black"},{"color":"red"}]
var colors = {colors: data.map(function(item){return item.color;})} // { "colors" : ["black" ,"red"] }
Some gotchas in your code:
You are using res.json in a for loop which is incorrect as the response should only be sent once. Ideally, you would build the JS object in the structure you need by iterating over your data and send the completed object once with res.json (which I'm guessing internally JSON.stringifys the object and sends it as a response after setting the correct headers)
Reading files is an expensive operation. If you can afford to read it once and cache that data in memory, it would be efficient (Provided your data is not prohibitively large - in which case using files to store info might be inefficient to begin with)
in express, you can do in this way
router.get('/colors/:name', (req, res) => {
const key = req.params.name
const content = fs.readFileSync(__dirname + '/data.json', 'utf8')
const data = JSON.parse(content)
const values = data.reduce((values, value) => {
values.push(value[key])
return values
}, [])
// values => ['black', 'red']
res.send(values)
});
and then curl http://localhost/colors/color,
you can get ['black', 'red']
What you're looking to do is:
res.json(data[i]['color']);
If you don't really want to use the keys in the json you may want to use the Object.values function.
...
data = JSON.parse(data)
var values = []
for (var i = 0; i < data.length; i++) {
values.push(Object.values(data[i])[0]) // 0 - color, 1 - category, 2 - type
}
res.json(values) // ["black","red"]
...
You should never use fs.readFileSync in production. Any sync function will block the event loop until the execution is complete hence delaying everything afterwords (use with caution if deemed necessary). A few days back I had the worst experience myself and learnt that in a hard way.
In express you can define a route with param or query and use that to map the contents inside fs.readFile callback function.
/**
* get color by name
*
* #param {String} name name of the color
* #return {Array} array of the color data matching param
*/
router.get('/colors/:name', (req, res) => {
const color = req.params.name
const filename = __dirname + '/data.json';
fs.readFile('/etc/passwd', 'utf8', (err, data) => {
if(err){
return res.send([]); // handle any error returned by readFile function here
}
try{
data = JSON.parse(data); // parse the JSON string to array
let filtered = []; // initialise empty array
if(data.length > 0){ // we got an ARRAY of objects, right? make your check here for the array or else any map, filter, reduce, forEach function will break the app
filtered = data.filter((obj) => {
return obj.color === color; // return the object if the condition is true
});
}
return res.send(filtered); // send the response
}
catch(e){
return res.send([]); // handle any error returned from JSON.parse function here
}
});
});
To summarise, use fs.readFile asynchronous function so that the event loop is not clogged up. Inside the callback parse through the content and then return the response. return is really important or else you might end up getting Error: Can't set headers after they are sent
DISCLAIMER This code above is untested but should work. This is just to demonstrate the idea.
I think you can’t access JSON without key. You can use Foreach loop for(var name : object){} check about foreach it may help you
I have a webserver with JSON data in it. This is what my data looks like
[
{
iduser: 1,
username: "joe",
password: "****"
},
{
iduser: 2,
username: "gina",
password: "****"
}
]
In my app I take some user input and wish to compare it to the username and password field. Here is where I check the data
.service('LoginService', function ($q, $http) {
return {
loginUser: function (name, pw) {
var deferred = $q.defer();
var promise = deferred.promise;
var user_data = $http.get("http://<my ip address>:<port>/login");
user_data.then(function ($scope, result) {
$scope.user = result.data;
})
for (var x in $scope.user) {
if (name == x.username && pw == x.password) {
deferred.resolve('Welcome ' + name + '!');
} else {
deferred.reject('Wrong credentials.');
}
}
promise.success = function (fn) {
promise.then(fn);
return promise;
}
promise.error = function (fn) {
promise.then(null, fn);
return promise;
}
return promise;
}
}
})
I am still learning angularJS and I know this is not a secure way to check the data I just want this loop to work.
My understanding of what I have here is that $scope.user holds my JSON data. Then the data is cycled through with the for loop and the user input name is compared to the field username of each iteration. But this is not the case as I am getting a fail every time.
I'm almost certain its a syntax error, but I don't know JavaScript or AngularJS well enough to find the problem. Any help is really appreciated, Thanks.
Edit 1
After what Nujabes said I made some changes since I don't need $scope.
//previous code the same
user_data.then(function (result) {
var user = result.data;
})
for (var x in user) {
if (name == x.username && pw == x.password) {
//prior code the same
I don't think var can hold the data and thats why I'm still getting errors. I think it should be in an array.
I think your syntax error is that you omit $scope.
You should inject $scope service to this line:
.service('LoginService',function($q,$http,$scope){ ...
});
And this code :
user_data.then(function ($scope, result) {
$scope.user = result.data;
});
Omit the $scope.
->
user_data.then(function (result) {
$scope.user = result.data;
});
like this.
Give it a try.
I hope it work.
(However, why do you want to use $scope service in your 'service'?
I think, defining local value and returning some method is a better choice.
and you use the $scope service in your 'controller'.)
$scope.user you are trying to loop through is array right ?
using (for/in) will store the key in the variable x which is in your case the index of each element (0,1,2,..) , to loop through arrays use (for/of) like this :
for (var value of array)
this will give you the values ...
Im using express, body-parser and moongose to build a RESTful web service with Node.js. Im getting json data in the body of a POST request, that function looks like this:
router.route('/match')
// create a match (accessed at POST http://localhost:3000/api/match)
.post(function(req, res) {
if (req._body == true && req.is('application/json') == 'application/json' ) {
var match = new Match(); // create a new instance of the match model
match.name = req.body.name; // set the match name and so on...
match.host = req.body.host;
match.clients = req.body.clients;
match.status = req.body.status;
// save the match and check for errors
match.save(function(err) {
if (err) {
//res.send(err);
res.json({ status: 'ERROR' });
} else {
res.json({ status: 'OK', Match_ID: match._id });
}
});
} else {
res.json({ status: 'ERROR', msg: 'not application/json type'});
}
});
The model Im using for storing a match in the database looks like this:
// app/models/match.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var MatchSchema = new Schema({
name: String,
host: String,
clients: { type: [String]},
date: { type: Date, default: Date.now },
status: { type: String, default: 'started' }
});
module.exports = mongoose.model('Match', MatchSchema);
But how do I validate that the json data in the body of the POST request has the key/value fields I want? For clarification, I dont want to insert data in the database that is incomplete. If I test to skip a key/value pair in the json data I get a missing field in the database and when I tries to read req.body.MISSING_FIELD parameter in my code I get undefined. All fields except date in the model is required.
Im using json strings like this to add matches in the database
{"name": "SOCCER", "host": "HOST_ID1", "clients": ["CLIENT_ID1", "CLIENT_ID2"], "status": "started"}
I use a very simple function that takes an array of keys, then loops through it and ensures that req.body[key] is not a falsy value. It is trivial to modify it to accommodate only undefined values however.
In app.js
app.use( (req, res, next ) => {
req.require = ( keys = [] ) => {
keys.forEach( key => {
// NOTE: This will throw an error for ALL falsy values.
// if this is not the desired outcome, use
// if( typeof req.body[key] === "undefined" )
if( !req.body[key] )
throw new Error( "Missing required fields" );
})
}
})
in your route handler
try{
// Immediately throws an error if the provided keys are not in req.body
req.require( [ "requiredKey1", "requiredKey2" ] );
// Other code, typically async/await for simplicity
} catch( e ){
//Handle errors, or
next( e ); // Use the error-handling middleware defined in app.js
}
This only checks to ensure that the body contains the specified keys. IT won't validate the data sent in any meaningful way. This is fine for my use case because if the data is totally borked then I'll just handle the error in the catch block and throw an HTTP error code back at the client. (consider sending a meaningful payload as well)
If you want to validate the data in a more sophisticated way, (like, say, ensuring that an email is the correct format, etc) you might want to look into a validation middle-ware, like https://express-validator.github.io/docs/