I have a simple web application that I am using with Node.js and Express. This is my package structure:
The contents of my questions.json file are as follows:
[
{
"question": "What is your favorite color?",
"id": 1
},
{
"question": "How old are you?",
"id": 2
},
]
And operations.json contains this:
var fs = require('fs');
const questions = 'public/questions.json';
class Operations{
constructor() {
fs.readFile(questions, (err, data) => {
if (err) throw err;
this.questions = JSON.parse(data);
});
}
findID(id) {
for (let key in this.questions) {
if (this.questions[key].id == id) {
console.log('found it!');
}
}
console.log("can't find it!...");
}
}
var test = new Operations();
test.findID(1);
This code used to work before but now for some odd reason, it is broken. The output of test.findID(1); Always returns can't find it... And I cannot figure out why. If I do a console.log(this.questions) outside of my constructor, it always prints undefined, but if I were to console.log(JSON.parse(data)) inside the callback function of the fs.readFile it will display the contents of the file.
Probably test.findID(1) is being executed before the actual IO reading happens, so at that moment, questions is undefined.
Try using fs.readFileSync instead of fs.readFile. This should be actually be fine, as you are still within the constructor of the object.
Related
A perplexing question. I am writing a node based command line tool that has a source json file, and then will take a changes JSON file (i.e. add, update, delete, etc) and I need to basically make the operation into a new JSON file and output to a new file. Not as simple as it sounds. With no command line arguments, etc. you would need to have a directive field in the JSON like so?
The app would work like this:
$ myapp source.json changes.json newfile.json
{
"action": "addRecord",
"payload": {
"id": "1",
"name": "James Hetfield",
"guitar": "More Beer"
}
},
"action": "deleteRecord",
"payload": {
"id": "3",
"name": "Dave Mustaine",
"guitar": "Ole Faithful"
}
}
My JSON structure is probably wrong as well, but wondering how you would use JSON.parse, JSON.stringify to read the file in with the fs library and actually make actions happen when identifying action and then execute a CRUD like statement with payload
Here is what I have so far:
#!/usr/bin/env node
// using fs for parsing for small example
const fs = require('fs');
// We do not simply require the file due to scaling.
// Large file will cause event locking. To handle
// even greater files we would use Node streams.
const file = './changes.json';
// target filename for output
const target = 'output.json';
fs.readFile(file, 'utf8', function(err, data) {
if (err) {
console.log('Error' + err);
return;
}
let obj = JSON.parse(data, (key, value) => {
if (key === 'action') {
if (value === 'addSong') {
return value = "Song Added";
}
if (value === "addPlaylist") {
return value = "Playlist added";
}
if (value === "deletePlaylist") {
return value = "Playlist deleted";
}
}
return value;
});
console.dir(obj);
});
fs seems to just read through the file and pick up the last value read. Not good. Wondering how to do the compare and possibly structure the JSON to make the action happen and then append? or transform the JSON into a new file with the update. Stuck.
I'm currently working on a NodeJS project, this takes data from a JSON and then use it to take weather stuff form an API, after that I want to save it to a DB, I already asked about it and that question helped me fixing some problems but now I have some others, I'm sending the data to a constant but the issue is that I don't know why am I getting an error in the JSON Parse, I want to use the lat and lon from the JSON (I have like a hundred data coords) and insert it into the const, any help would help, This is the error I'm getting
Successful connection
[]
undefined:1
^
SyntaxError: Unexpected token in JSON at position 0
at JSON.parse (<anonymous>)
here is my function that takes data from JSON and gets data from the API:
async function calcWeather() {
fs.readFile("./json/data.json","utf8", function (err, data) {
if(err) throw err;
data2 = JSON.parse(data);
console.log(typeof data2);
for (let item of data2) {
let base = `https://api.openweathermap.org/data/2.5/weather?lat=${item.latjson}&lon=${item.lonjson}&appid=${api_key}&units=metric&lang=sp`;
fetch(base)
.then((responses) => {
return responses.json();
})
.then((data) => {
var myObject = {
Id_Oficina: item.IdOficina,
Humedad: data.main.humidity,
Nubes: data.clouds.all,
Sensacion: data.main.feels_like,
Temperatura: data.main.temp,
Descripcion: data.weather.description,
};
// validation and saving data to array
if (myObject.Temperatura < 99) {
lstValid.push(myObject);
}
});
}
});
console.log(lstValid);
}
here is the JSON where I take the data:
[
{
"latjson": 1,
"lonjson": 1,
"IdOficina": "1"
},
{
"latjson": 2,
"lonjson": 2,
"IdOficina": "2"
}
]
I think the issue is in the parse, but I don't get what I am doing wrong
Since you are reading the file with fs.readFile, you are getting a string and not a JavaScript object. You would need to parse it entirely in order to be able to manipulate the content (you seem to be parsing the first character only):
const fs = require('fs')
let rawdata = fs.readFileSync('./data.json')
let data = JSON.parse(rawdata)
Personally, I think it's way easier to require it (no need to use fs):
const jsonData = require('./json/data.json')
async function calcWeather() {
for (let item of jsonData) {
// ...
}
}
Basically, this shouldn´t be a very difficult question, but I´ve tried for like 2 or 3 hours and couldnt reach my goal, especially for such an "easy" question. Im using Node.js and my goal is, to load data from a Json file into a variable, add some new data to this and store my data into the same json file again.
Herefor, my json file looks like this:
[
{
"name": "Max",
"date": "1.1.2020"
}, {
"name": "Henry",
"date": "2.2.2020"
}
]
Here´s my code:
const fs = require('fs');
const filename = './jsonFile.json';
const data = loadJSON();
// console.log(data) keeps saying undefined (whithout using .toString in loadJSON)
function loadJSON() {
JSON.parse(fs.readFileSync(filename).toString); // toString doesnt work
}
function saveJSON(data) {
fs.writeFileSync(filename, JSON.stringify(data));
}
function adduser(username) {
var today = "3.3.2020"; // doesnt matter
let obj = {
name: username,
date: today
}
vipJson.push(obj);
saveVIP(vipJson);
}
It doesnt seem to be working. Could anyone help me, to fix my problem, so I can work with .json files ? Thanks a lot!
You need to specify the BufferEncoding options to read the file, something like this.
const fs = require("fs")
const data = fs.readFileSync("./myfile.json", { encoding: "utf8", flag: "r" })
If you are sure about json files, you can read data from file using require.
const fs = require('fs');
const filename = './jsonFile.json';
const data = loadJSON();
function loadJSON() {
return require(filename)
}
function saveJSON(data) {
fs.writeFileSync(filename, JSON.stringify(data));
}
function adduser(username) {
var today = "3.3.2020"; // doesnt matter
let obj = {
name: username,
date: today
}
data.push(obj);
saveJSON(data);
}
Try above code snippet.
I have an array of objects, each one is a file with properties name, path, extension, and so on, like this:
module.exports = {
logpath: "C:\\",
logsfiles: [
{
name: "log1", // file name
path: this.logpath, // path to log
extension: ".log", // log extension
type: "server", // component type (server, connector-hub, connector-component, gateway)
licensed: true, // boolean for license holder
iis: false, // boolean for iis exposure
application: "N/A" // solution
},
{
name: "log2", // file name
path: this.logpath, // path to log
extension: ".log", // log extension
type: "server", // component type (server, connector-hub, connector-component, gateway)
licensed: true, // boolean for license holder
iis: false, // boolean for iis exposure
application: "N/A" // solution
}
]
}
And I need to iterate through this list by reading the entire file, search for a specific string and, if this string exists, store some of the file properties into an array.
What I have so far is this:
function getFile(log) {
return new Promise((resolve, reject) => {
fs.readFile(
logConfig.logpath + log.name + log.extension,
"utf8",
(err, data) => {
if (err) {
console.log(`Error reading file ${log.name}`);
reject(err);
} else {
if (data.indexOf("String pattern to search") != -1)
resolve({ name: log.name, componentkey: "TODO" });
}
}
);
});
}
I know this piece of code is working if I call it standalone. But if I try to call it inside of a loop like this:
async function getAllFiles(logs) {
const finalArray = [];
const promises = logs.map(async log => await getFile(log));
const results = await Promise.all(promises);
finalArray.push(results);
console.log(finalArray); //not printing
console.log("Done"); //not printing
}
Nothing happens... The last two prints doesn't show on the console...
Can anyone help me by showing me what am I doing wrong?
Noob with promises here, sorry... :) And many thanks in advance!
Ah! Got it!
Stupid!
The getFile(log) return promise was not resolving all of the items since I didn't had an else statement to the if (data.indexOf("String pattern to search") != -1).
Covered that and now I get results!
Thank you!
I have the below json response after running a postMan test of a Rest API:
{
"glossary": {
"title": "example glossary",
"GlossDiv": {
"title": "S",
"GlossList": {
"GlossEntry": {
"ID": "SGML",
"SortAs": "SGML",
"GlossTerm": "Standard Generalized Markup Language",
"Acronym": "SGML",
"Abbrev": "ISO 8879:1986",
"GlossDef": {
"para": "A meta-markup language, used to create markup languages such as DocBook.",
"GlossSeeAlso": ["GML", "XML"]
},
"GlossSee": "markup"
}
}
}
}
}
Now I would like to compare the above json against a predefined json. Say, its the same as above.
How can I compare two jsons via the Postman test?
I had a similar problem to solve except that my JSON also contained an array of objects. I used the following technique that can be modified to deal with the simple array of strings in your question.I created an array of global functions called "assert", which contained helper functions such as "areEqual" and "areArraysOfObjectsEqual" and saved these under the "Tests" tab at a top folder level of my tests.
assert = {
areEqual: (actual, expected, objectName) => {
pm.test(`Actual ${objectName} '` + actual + `' matches Expected ${objectName} '` + expected + `'`, () => {
pm.expect(_.isEqual(actual, expected)).to.be.true;
});
},
areArraysOfObjectsEqual: (actual, expected, objectName) => {
if (!_.isEqual(actual, expected)) {
// Arrays are not equal so report what the differences are
for (var indexItem = 0; indexItem < expected.length; indexItem++) {
assert.compareArrayObject(actual[indexItem], expected[indexItem], objectName);
}
}
else
{
// This fake test will always pass and is just here for displaying output to highlight that the array has been verified as part of the test run
pm.test(`actual '${objectName}' array matches expected '${objectName}' array`);
}
},
compareArrayObject: (actualObject, expectedObject, objectName) => {
for (var key in expectedObject) {
if (expectedObject.hasOwnProperty(key)) {
assert.areEqual(expectedObject[key], actualObject[key], objectName + " - " + key);
}
}
}
};
Your "Pre-request Script" for a test would set your expected object
const expectedResponse =
{
"id": "3726b0d7-b449-4088-8dd0-74ece139f2bf",
"array": [
{
"item": "ABC",
"value": 1
},
{
"item": "XYZ",
"value": 2
}
]
};
pm.globals.set("expectedResponse", expectedResponse);
Your Test would test each item individually or at the array level like so:
const actualResponse = JSON.parse(responseBody);
const expectedResponse = pm.globals.get("expectedResponse");
assert.areEqual(
actualResponse.id,
expectedResponse.id,
"id");
assert.areArraysOfObjectsEqual(
actualResponse.myArray,
expectedResponse.myArray,
"myArrayName");
This technique will give nice "property name actual value matches expected value" output and works with arrays of objects being part of the JSON being compared.
Update:
To test your array of strings "GlossSeeAlso", simply call the supplied global helper method in any of your tests like so:
assert.compareArrayObject(
actualResponse.glossary.GlossDiv.GlossList.GlossEntry.GlossDef.GlossSeeAlso,
expectedResponse.glossary.GlossDiv.GlossList.GlossEntry.GlossDef.GlossSeeAlso,
"glossary.GlossDiv.GlossList.GlossEntry.GlossDef.GlossSeeAlso");
Primitive types in JSON key value pairs can be tested like so:
assert.areEqual(
actualResponse.glossary.title,
expectedResponse.glossary.title,
"glossary.title");
I got it after a while. Add test into your request and use Runner to run all your requests in the collection.
Postman info: Version 7.10.0 for Mac.
Test scripts:
pm.test("Your test name", function () {
var jsonData = pm.response.json();
pm.expect(jsonData).to.eql({
"key1": "value1",
"key2": 100
});
});
You can paste this code into your collection or single request tests tab.
What this code do is to save the request into a global variable with a key for that request. You can change your enviroment and hit the same request and if the response are different the test will fail.
const responseKey = [pm.info.requestName, 'response'].join('/');
let res = '';
try {
res = JSON.stringify(pm.response.json());
} catch(e) {
res = pm.response.text();
}
if (!pm.globals.has(responseKey)) {
pm.globals.set(responseKey, res);
} else {
pm.test(responseKey, function () {
const response = pm.globals.get(responseKey);
pm.globals.unset(responseKey);
try {
const data = pm.response.json();
pm.expect(JSON.stringify(data)).to.eql(response);
} catch(e) {
const data = pm.response.text();
pm.expect(data).to.eql(response);
}
});
}
Hope this help.
You can write javascript code inside Tests tab of Postman. Just write simple code to compare and check result in Tests.
var serverData = JSON.parse(responseBody);
var JSONtoCompare = {}; //set your predefined JSON here.
tests["Body is correct"] = serverData === JSONtoCompare;
Looks like the same question asked at POSTMAN: Comparing object Environment variable with response's object which also lists a solution that works, which is to use JSON.stringify() to turn the objects into strings and then compare the strings.
Came across this issue when migrating from a legacy API to a new one and wanting to assert the new API is exactly the same as the old under different scenarios
For context this clones params of the original get request to the legacy endpoint and validates both match up
LEGACY_API_URL should be defined in the environment and the Request is going to the new API
const { Url } = require('postman-collection');
// Setup the URL for the Legacy API
const legacyRequestUrl = new Url({ host: pm.variables.replaceIn("http://{{LEGACY_API_HOST}}/blah")});
// Add All Parameters From the Source Query
legacyRequestUrl.addQueryParams(pm.request.url.query.all());
// Log out the URL For Debugging Purposes
console.log("URL", legacyRequestUrl.toString());
pm.sendRequest(legacyRequestUrl.toString(), function (err, response) {
pm.test('New API Response Matches Legacy API Response', function () {
// Log Out Responses for Debugging Purposes
console.log("New API Response", pm.response.json())
console.log("Legacy API Response", response.json())
// Assert Both Responses are Equal
pm.expect(_.isEqual(pm.response.json(), response.json())).to.be.true
});
});
Link to an example collection
https://www.getpostman.com/collections/4ff9953237c0ab1bce99
Write JavaScript code under 'Tests' section. Refer below link for more info.
Click Here