I have been having a bit of trouble appending new dynamic data to a JSON file. To sum up my project, I take in the projectName from an input form at the /new page.
My API is then using the node.js's fs module to create a new JSON file with which I can then append the new dynamic data upon subsequential requests to my form. The variables are 1) projectName (is taken in from my form), 2) activeUser (which is programmed in through an environmental variable), 3) is the date of the request which I am acquiring through a timestamp variable with this function:
const timestamp = (JSON.parse(JSON.stringify(new Date())));
All three of these variables seem to print correctly for 2 subsequent requests and then on the third form submission there seems to be no new data appending to the JSON file. However i am relatively new to node.js and I can't seem to figure out where I am messing this up.
This is my API
pages/api/demos/index.js
import dbConnect from '../../../lib/dbConnect';
import Demo from '../../../models/Demo';
import fs from 'fs';
export default async function handler(req, res) {
const {
query: { id },
method,
} = req
await dbConnect()
switch (method) {
case 'POST':
try {
//check if file exist
if (!fs.existsSync('projects.json')) {
//create new file if not exist
fs.closeSync(fs.openSync('projects.json', 'w'));
}
// read file
const timestamp = (JSON.parse(JSON.stringify(new Date())));
const newFileName = req.body.projectName;
const activeUser = process.env.ACTIVE_USERNAME;
const file = fs.readFileSync('projects.json')
const data = {
"projects": [
{
"username": activeUser,
"pages": [
{
"display": "routes",
"subpages": [
{
"date": timestamp,
"route": newFileName,
"display": newFileName
}
]
}
]
}
]
}
//check if file is empty
if (file.length == 0) {
//add data to json file
fs.writeFileSync("projects.json", JSON.stringify([data]))
} else {
//append data to jso file
const json = JSON.parse(file.toString())
//add json element to json object
json.push(data);
fs.appendFileSync("projects.json", JSON.stringify(data))
}
const demo = await Demo.create(
req.body
)
res.status(201).json({ success: true, data: demo })
} catch (error) {
res.status(400).json({ success: false })
}
break
default:
res.status(400).json({ success: false })
break
}
}
After the first form submission my JSON file projects.json looks like
[
{
"projects": [
{
"username": "projectmikey",
"pages": [
{
"display": "routes",
"subpages": [
{
"date": "2022-09-12T19:03:09.547Z",
"route": "1",
"display": "1"
}
]
}
]
}
]
}
]
and then after the 2nd form submission
[
{
"projects": [
{
"username": "projectmikey",
"pages": [
{
"display": "routes",
"subpages": [
{
"date": "2022-09-12T19:03:09.547Z",
"route": "1",
"display": "1"
}
]
}
]
}
]
}
]{
"projects": [
{
"username": "projectmikey",
"pages": [
{
"display": "routes",
"subpages": [
{
"date": "2022-09-12T19:03:24.466Z",
"route": "2",
"display": "2"
}
]
}
]
}
]
}
Oddly it seems to work for two form submissions and then the data stops appending to my file. This is after the third attempt, (no change to the file)
[
{
"projects": [
{
"username": "projectmikey",
"pages": [
{
"display": "routes",
"subpages": [
{
"date": "2022-09-12T19:03:09.547Z",
"route": "1",
"display": "1"
}
]
}
]
}
]
}
]{
"projects": [
{
"username": "projectmikey",
"pages": [
{
"display": "routes",
"subpages": [
{
"date": "2022-09-12T19:03:24.466Z",
"route": "2",
"display": "2"
}
]
}
]
}
]
}
It seems to stop working at all when I remove the pair of brackets around the initial JSON object. The line I am refering to is fs.writeFileSync("projects.json", JSON.stringify([data]))
I could really use another pair of eyes on this so I can see where I am messing this up! lol Thanks in advance for your time...
Although it feels like you are "appending" to the file, you are actually doing something more complicated.
e.g. before state:
[ "one", "two" ]
desired after-state:
[ "one", "two", "three" ]
Notice that you can't just append text to the before-state JSON because there's already that pesky ] terminating the whole object.
Some failed attempts might look like:
failed attempt to append another entire array
[ "one", "two" ][ "three" ]
This is invalid because there are two root objects.
failed attempt to append just the rest of the array
[ "one", "two" ], "three" ]
That's no good either. The ] at the end of the original file needs to be overwritten or removed, so there's no way to just append. I suppose technically you could seek to the position of the final ] and then continue writing an incomplete object from there. But this is very awkward to remove the final ] from the source and to remove the initial [ from the chunk you're trying to append. It's just a difficult approach.
What you actually want to do is:
read the entire JSON file
parse the JSON into a JavaScript object (or create an empty object if the file didn't exist)
Modify the JavaScript object as necessary (e.g. push into the array to add another element)
stringify the JavaScript object into new JSON
overwrite the entire file with the new JSON.
/* In Node.js:
const fs = require('fs');
try {
initialJSON = fs.readFileSync('example.json');
} catch (ignore) {
initialJSON = '[]';
}
*/
/* Mocked for this example: */
initialJSON = '["one","two"]';
// Common
obj = JSON.parse(initialJSON);
obj.push("three");
finalJSON = JSON.stringify(obj);
/* In Node.js:
fs.writeFileSync('example.json', finalJSON);
*/
/* Mocked for this example: */
console.log(finalJSON);
Related
I am using mongoose in nodejs(express) in backend. My array structure has THREE levels. At third level, some files are present. But I need to add entries at any level as per user demand.
[
{
"name": "A folder at",
"route": "level1_a"
},
{
"name":"Another folder at Level1",
"route": "level1_b",
"children":
[
{
"name": "A folder at Level2",
"route": "level1_b/level2_a",
"children":
[
{
"name": "A folder at Level3",
"route": "level1_b/level2_a/level3_a",
"children":
[
{
"name": "A file at last level",
"route": "level1_b/level2_a/level3_a/file1"
},
{
"name": "Add a new File",
"route":"level1_b/level2_a/level3_a/new_file"
}
]
},
{
"name": "Add Folder at Level3",
"route":"level1_b/level2_a/new_folder"
}
]
},
{
"name": "Add Folder at level2",
"route":"level1_b/new_folder"
}
]
},
{
"name": "Add Folder at Level1",
"route":"new_folder"
}
]
Now I have to add an entry at a specified position. Suppose at level2, I need to add a folder. For adding, two parameters are sent from angular to the backend. These will be 'name' and a 'route'. So my entry would be having {name: 'Products', route: 'level1_a/products'} and similarily should be placed at correct position i.e. inside the children of level1_a.
My backend has a schema which would be like:
const navSchema = mongoose.Schema({
name:{type:String,required:true},
route:{type:String},
children:{
type: {
name:{type:String,required:true},
route:{type:String},
}}
});
module.exports = mongoose.model('NatItems',navSchema);
And the API would be like:
router.post('/navlist',(req,res,next)=>{
const name= req.body.folder;
const route= req.body.url;
console.log(folder,url);//it will be required parameters like name: 'Products', route:'level1_a/products'
//let pathArray = route.split('/'); //if you want you can split the urls in the array
//Help me write the code here
res.status(201).json({
message:"Post added successfully!"
})
})
Please help me in adding entries in db. I know navlist.save() adds an entry directly but I am not able to add entries in a nested manner.
PS: I can't change the array structure because this array is easily read by angular and a complete navigation menu is made!! I am working for first time in nodejs and mongoose, so I am having difficulty in writing code with mongoose function.
For the scenario you've provided ({name: 'Products', route: 'level1_a/products'}) the update statement is pretty straightforward and looks like this:
Model.update(
{ route: "level1_a" },
{ $push: { children: {name: 'Products', route: 'level1_a/products'} } })
Things are getting a little bit more complicated when there are more than two segments in the incoming route, e.g.
{ "name": "Add a new File", "route":"level1_b/level2_a/level3_a/new_file2" };
In such case you need to take advantage of the positional filtered operator and build arrayFilters and your query becomes this:
Model.update(
{ "route": "level1_b"},
{
"$push": {
"children.$[child0].children.$[child1].children": {
"name": "Add a new File",
"route": "level1_b/level2_a/level3_a/new_file2"
}
}
},
{
"arrayFilters": [
{
"child0.route": "level1_b/level2_a"
},
{
"child1.route": "level1_b/level2_a/level3_a"
}
]
})
So you need a function which loops through the route and builds corresponding update statement along with options:
let obj = { "name": "Add a new File", "route":"level1_b/level2_a/level3_a/new_file2" };
let segments = obj.route.split('/');;
let query = { route: segments[0] };
let update, options = {};
if(segments.length === 2){
update = { $push: { children: obj } }
} else {
let updatePath = "children";
options.arrayFilters = [];
for(let i = 0; i < segments.length -2; i++){
updatePath += `.$[child${i}].children`;
options.arrayFilters.push({ [`child${i}.route`]: segments.slice(0, i + 2).join('/') });
}
update = { $push: { [updatePath]: obj } };
}
console.log('query', query);
console.log('update', update);
console.log('options', options);
So you can run:
Model.update(query, update, options);
I have to construct a JSON payload that looks like this, can someone help me? I am able to get the straight forward one but unable to build a nested payload. How do I go about adding more nested keys, one inside the other. Also some of the keys and values are dynamic and have to replaced with variables.
{
"format_version": "0.2.19",
"alliances": {
"xyz": {
"environments": {
"prd": {
"teams": {
"abc": {
"action": "edit",
"team": "abc",
"projects": {
"prjabc": {
"project": "prjabc",
"cost_center": "0",
"custom_iam_policies": [],
"iam": {
"view_group_email_name": "abc#email.com",
"sre_admin_group_email_name": "xyz#email.com"
},
"allowed_apis": [
"api1",
"api2"
],
"networks": {
"network1": {
"flags": [
"VM"
],
"region": "sample-region",
"preferred-suffix": "routable"
}
}
}
}
}
}
}
}
}
}
}
Let say you have an object as such
items = {
foo: "bar",
something: "useful"
}
and if you wanted to add other properties or add nested object you can do so like this
subitems = { name: "Johnson" };
items['subitem'] = subitems;
After you've added and finalized the object, you can just use JSON.stringify(items) to convert your object into "payload"
I am trying to gain access within the last array of the json file and return the value from the "data" array of the json file and put it into the choiceSelection array. However, on my local host, it returns an undefined value and the images would not load. Can anyone help me out? I apologise if I haven't clearly explained my problem/logic and so please ask me for more details, if you're not sure. Thanks!
javascript code
$.getJSON('data.json', function(json) {
if(json[2].data){
for (i = 0; i < json[3].data.length; i++) {
choiceSelection[i] = new Array;
choiceSelection[i][0] = json[2].data[i].question;
choiceSelection[i][1] = json[2].data[i].correctChoice;
choiceSelection[i][2] = json[2].data[i].choice1;
choiceSelection[i][3] = json[2].data[i].choice2;
}
// choiceSelection.length = choiceSelection.length;
displayQuestion();
console.log(json[2]);
}
})
json file
[
{
"name": "match numbers 1",
"template": "matching",
"data": [
[
"six",
"Images/Number6.jpg"
],
[
"eight",
"Images/Number8.jpg"
],
[
"nine",
"Images/Number9.jpg"
]
]
},
{
"name": "order numbers 1",
"template": "ordering",
"data": [
[
"Images/Number6.jpg"
],
[
"Images/Number8.jpg"
],
[
"Images/Number9.jpg"
]
]
},
{
"name": "animal",
"template": "picture game",
"data": [
{
"question": "Where is the cat?",
"correctChoice": "Images/5cats.jpg",
"choice1": "Images/squirrel.png",
"choice2": "Images/beagle.png"
},
{
"question": "Where is the cat?",
"correctChoice": "Images/5cats.jpg",
"choice1": "Images/squirrel.png",
"choice2": "Images/beagle.png"
}
]
}
]
Edit 1: change json[i] to json[2].data. Still undefined
Edit 2: changed json[2].data. to json[2].data[i] and used json[3].data.length in the for statement. It works perfectly now. Thank you everyone for the help!:)
You could take the hassle out of your code and use some ES6 destructuring to get at your data more easily.
const json = '[{"name":"match numbers 1","template":"matching","data":[["six","Images/Number6.jpg"],["eight","Images/Number8.jpg"],["nine","Images/Number9.jpg"]]},{"name":"order numbers 1","template":"ordering","data":[["Images/Number6.jpg"],["Images/Number8.jpg"],["Images/Number9.jpg"]]},{"name":"animal","template":"picture game","data":[{"question":"Where is the cat?","correctChoice":"Images/5cats.jpg","choice1":"Images/squirrel.png","choice2":"Images/beagle.png"},{"question":"Where is the cat?","correctChoice":"Images/5cats.jpg","choice1":"Images/squirrel.png","choice2":"Images/beagle.png"}]}]'
function getJSON(endpoint, callback) {
setTimeout(() => callback(JSON.parse(json)), 1000);
}
// grab the third object from the response data
getJSON('data.json', function([ ,,obj ]) {
// grab the data array from that object but relabel it
// `choiceSelection
const { data: choiceSelection } = obj;
// then use the object property keys to get access
// to the data instead of indexes. Much easier.
console.log(choiceSelection[0].question);
console.log(choiceSelection[1].question);
});
The server I'm working with changed the REST format from plain JSON:
{
"removedVertices": [
{
"id": "1",
"info": {
"host": "myhost",
"port": "1111"
},
"name": "Roy",
"type": "Worker"
}
],
"id": "2",
"time": 1481183401573
}
To Jackson format:
{
"removedVertices": [
"java.util.ArrayList",
[
{
"id": "1",
"info": [
"java.util.HashMap",
{
"host": "myhost",
"port": "1111"
}
]
"name": "Roy",
"type": "Worker",
}
]
"id": "2",
"time": 1482392323858
}
How can I parse it the way it was before in Angular/Javascript?
Assuming only arrays are affected, I would use underscore.js and write a recursive function to remove the Jackson type.
function jackson2json(input) {
return _.mapObject(input, function(val, key) {
if (_.isArray(val) && val.length > 1) {
// discard the Jackson type and keep the 2nd element of the array
return val[1];
}
else if (_.isObject(val)) {
// apply the transformation recursively
return jackson2json(val);
}
else {
// keep the value unchanged (i.e. primitive types)
return val;
}
});
}
If the api should be restful, then the server should not return none plain json results. I think the server site need to fix that.
I think it is because the server enabled the Polymorphic Type Handling feature.
Read Jackson Default Typing for object containing a field of Map and JacksonPolymorphicDeserialization.
Disable the feature and you will get result identical to plain json.
The main difference i see is that in arrays you have an additional string element at index 0.
If you always get the same structure you can do like this:
function jacksonToJson(jackson) {
jackson.removedVertices.splice(0, 1);
jackson.removedVertices.forEach((rmVert) => {
rmVert.info.splice(0, 1);
});
return jackson;
}
I'm creating a JSON object from an array and I want to dynamically push data to this JSON object based on the values from array. See my code for a better understanding of my problem...
for(i=0;i<duplicates.length; i++) {
var request = {
"name": duplicates[i].scope,
"id": 3,
"rules":[
{
"name": duplicates[i].scope + " " + "OP SDR Sync",
"tags": [
{
"tagId": 1,
"variables":[
{
"variable": duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
}
],
"condition": false,
},
{
"tagId": 1,
"condition": false,
}
],
"ruleSetId": 3,
}
]
}
}
I take object properties from the duplicates array that can have the following elements:
[{scopeDef=.*, scope=Global, variable=[trackingcode, v1, v2]}, {scopeDef=^https?://([^/:\?]*\.)?delta.com/products, scope=Products Section, variable=[v3]}]
As you can see, an object contain variable element that can have multiple values. I need to push to the JSON object all those values dynamically (meaning that there could be more than 3 values in an array).
For example, after I push all the values from the duplicates array, my JSON object should look like this:
name=Products Section,
rules=
[
{
name=Products Section OP SDR Sync,
tags=[
{
variables=
[
{
matchType=Regex,
variable=v3,
value=^https?://([^/:\?]*\.)?delta.com/products
},
{
matchType=Regex,
variable=trackingcode,
value=.*
},
{
matchType=Regex,
variable=v1,
value=.*
},
{
matchType=Regex,
variable=v2,
value=.*
}
],
condition=false,
},
{
condition=false,
tagId=1
}
],
ruleSetId=3
}
]
}
I tried the following code but without success:
for(var j in duplicates[i].variable) {
var append = JSON.parse(request);
append['variables'].push({
"variable":duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
})
}
Please let me know if I need to provide additional information, I just started working with JSON objects.
First of all, you dont need to parse request, you already create an object, parse only when you get JSON as string, like:
var json='{"a":"1", "b":"2"}';
var x = JSON.parse(json);
Next, you have any property of object wrapped in arrays. To correctly work with it you should write:
request.rules[0].tags[0].variables.push({
"variable":duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
})
If you want to use your code snippet, you need some changes in request:
var request = {
"name": duplicates[i].scope,
"id": 3,
"variables":[
{
"variable": duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
}
],
"rules":[
{
"name": duplicates[i].scope + " " + "OP SDR Sync",
"tags": [
{
"tagId": 1,
"condition": false,
},
{
"tagId": 1,
"condition": false,
}
],
"ruleSetId": 3,
}
]
}
}
To understand JSON remember basic rule: read JSON backward. It means:
property
object.property
arrayOfObfects['id'].object.property
mainObject.arrayOfObfects['id'].object.property
and so on. Good luck!