How to get JSON array from file with getJSON? - javascript

How could I get an array json of a json file with javascript and jquery
I was triyng with the next code, with it doesnt work:
var questions = [];
function getArray(){
$.getJSON('questions.json', function (json) {
for (var key in json) {
if (json.hasOwnProperty(key)) {
var item = json[key];
questions.push({
Category: item.Category
});
}
}
return questions;
})
}
this is the json file called: questions.json
{
"Biology":{
"Category":{
"cell":{
"question1":{
"que1":"What is the cell?"
},
"option1":{
"op1":"The cell is the basic structural and functional unit",
"op2":"is a fictional supervillain in Dragon Ball"
},
"answer1":"opt1"
}
}
},
"Astronomy":{
"Category":{
"Mars":{
"question1":{
"que1":"How many moons does Mars?"
},
"option1":{
"op1":"5",
"op2":"2"
},
"answer1":"opt2"
}
}
}
}
I want to get an array with this format {Biology:{Category:{cell:{question1....}}}}

$.getJSON is an asynchronous function, so returning something inside that function does nothing, as it's not in scope, or received yet. You should probably do something like:
function getArray(){
return $.getJSON('questions.json');
}
getArray().done(function(json) {
// now you can use json
var questions = [];
$.each(json, function(key, val) {
questions[key] = { Category: val.Category };
});
});

Your conditional within the for loop prevents anything from being added to your array. Instead, check if your json object has the property, then get the value and add it to your array. In other words:
if (questions.hasOwnProperty(key)) should be if (json.hasOwnProperty(key))
Also, you can't simply return the result of an AJAX call like that, because the method runs asynchronously. That return is actually applied to the inner success function callback, not getArray. You have to use a callback pattern in order to pass the data only once it has been received, and operate on it accordingly.
(Of course since the array is defined in the outer scope you wouldn't have to return it anyway, but if you attempted to use it before the AJAX method ended it would be empty.)
Assuming you are going to render it to the DOM using a method called renderJSON:
var questions = [];
function getArray(){
$.getJSON('questions.json', function (json) {
for (var key in json) {
if (json.hasOwnProperty(key)) {
var item = json[key];
questions.push({
Category: item.Category
});
}
}
renderJSON(questions);
});
}

Related

Pass a javascript function as part of a JSON [duplicate]

I've been looking around for a way to do this but can't seem to find anything, I have different configuration objects that I need to save as a text in variables for some processing later on, here is a sample:
object:
args.config.config = {
next: null,
final:[],
delimiter: '~', header: false,
step: function (row) {
var item = {
'line_code': row.data[0][0],
'order': row.data[0][1]
}
args.config.config.final.push(item);
},
complete: function (result) {
console.log('Reading data completed. Processing.');
return args.config.config.next(null, args.config.config.final);
},
error: function () {
console.log('There was an error parsing');
}'
}
I need to save this as a string, so something like:
args.config.config = "{object goes here}";
Without putting everything on one giant line or adding break line characters as this will be parsed later to be used in a config, and that will mess things up, any ideas?
UPDATE:
So changing them into text may not be the best solution, these configs will be stored in a mongo database, so it may take them as is (I have not tried it yet).
One of the other problems I was running into was that in the config object I had this:
final.push(item)
and
return next(null, final)
Which will be defined in another file using the config object:
other file:
exports.parse = function(args, next){//next is what I need to call in the config
var final = []; //this is the final referred to in the config object
....
Baby.parse(data, args.config)
}
So the return next(null, final) and final.push(result) have to refer the the var / function in the new file, but I have no idea how to get that to work, that't why I had to add a final array in the config object and a null next function, then assign it like so:
exports.parse = function(args, next){
args.config.next = next;
....
Baby.parse(data, args.config)
}
the object was calling it with the ugly line:
return args.config.config.next(null, args.config.config.final);
If anyone has a way around this, it would be much appreciated.
If you use JSON.stringify with a "replacer" function and
JSON.parse with a "reviver" function along with new Function(), you can do it:
I'm not sure I'm following the second (updated) question you have. Once the object is parsed back into an object, why can't you just initialize the next and final properties to valid objects before calling any of the object's methods? You can even add tests into that method that checks for the existence of final and next before returning anything.
var myObj = {
next: null,
final:[],
delimiter: '~',
header: false,
step: function (row) {
var item = {
'line_code': row.data[0][0],
'order': row.data[0][1]
};
args.config.config.final.push(item);
},
complete: function (result) {
console.log('Reading data completed. Processing.');
return args.config.config.next(null, args.config.config.final);
},
error: function () {
console.log('There was an error parsing');
}
};
// Stringify the object using a replacer function that will explicitly
// turn functions into strings
var myObjString = JSON.stringify(myObj, function(key, val) {
return (typeof val === 'function') ? '' + val : val;
});
// Now, parse back into an object with a reviver function to
// test for function values and create new functions from them:
var obj = JSON.parse(myObjString, function(key, val){
// Make sure the current value is not null (is a string)
// and that the first characters are "function"
if(typeof val === "string" && val.indexOf('function') === 0){
// Isolate the argument names list
var start = val.indexOf("(") + 1;
var end = val.indexOf(")");
var argListString = val.substring(start,end).split(",");
// Isolate the body of the function
var body = val.substr(val.indexOf("{"), val.length - end + 1);
// Construct a new function using the argument names and body
// stored in the string:
return new Function(argListString, body);
} else {
// Non-function property, just return the value
return val;
}
}
);
// Test the method:
obj.error(); // 'There was an error parsing' is written to console.
// Examine the object:
console.log(obj);

Javascript Array.prototype.filter() not working

I have this piece of code running on the client that filters a list of events:
if (res)
{
eventList.filter(function(event) {
const out = res.find(function(visibility) { return visibility.ID == event.id; }) == undefined;
return out;
});
alert(eventList);
}
displayEvents(eventList);
The problem is that even when out is false the element is not filtered out.
Just for debug I tried to return false in any case and the resulting array still had all the initial elements:
eventList.filter(function(event) {
return out;
});
What am I doing wrong here??
EDIT:
res is an array of JSON objects (containg only ID field) returned by the server, while eventList is a list of Facebook events, passed to this callback function from a Facebook API request
Array.prototype.filter does not change array inplace, it returns new array made of items that satisfies the provided predicate. It should look like this
var result = eventList.filter(function(event) {
return res.find(function(visibility) { return visibility.ID == event.id; }) === undefined;
});
You don't need to declare and assign variable and then return it from function, you can simply return expression

Have a recursive function call on each key in a for loop parsing json

Say I have a json object that looks like
"bounds":{
"coordinatetop":{
"x":143,
"y":544
},
"coordinatebottom":{
"x":140,
"y":510
}
}
I am trying to parse the JSON currently with this code, where data is the json data and target is just an tag id.
$.each(data, function(index, value) {
if (typeof(value) == 'object') {
processBounds(value, target);
} else {
console.log(value);
}
});
When I loop through this, the function call takes the values coordinatetop and target, followed by the value of x and y which are 143 and 544. However, this function does not loop far enough to get the values of coordinatebottom.
What are other ways of implementation to make that possible? Thanks
In fact you aren't calling the function recursively, you are just binding a callback function that calls processBounds() function.
You need to declare the processBounds function separately then bind it in the .each callback:
var processBounds = function(index, value) {
if (typeof(value) == 'object') {
processBounds(value, target);
} else {
console.log(value);
}
}
$.each(data, processBounds);
Edit:
$.each(data.bounds, processBounds);

JavaScript - Save object with methods as a string

I've been looking around for a way to do this but can't seem to find anything, I have different configuration objects that I need to save as a text in variables for some processing later on, here is a sample:
object:
args.config.config = {
next: null,
final:[],
delimiter: '~', header: false,
step: function (row) {
var item = {
'line_code': row.data[0][0],
'order': row.data[0][1]
}
args.config.config.final.push(item);
},
complete: function (result) {
console.log('Reading data completed. Processing.');
return args.config.config.next(null, args.config.config.final);
},
error: function () {
console.log('There was an error parsing');
}'
}
I need to save this as a string, so something like:
args.config.config = "{object goes here}";
Without putting everything on one giant line or adding break line characters as this will be parsed later to be used in a config, and that will mess things up, any ideas?
UPDATE:
So changing them into text may not be the best solution, these configs will be stored in a mongo database, so it may take them as is (I have not tried it yet).
One of the other problems I was running into was that in the config object I had this:
final.push(item)
and
return next(null, final)
Which will be defined in another file using the config object:
other file:
exports.parse = function(args, next){//next is what I need to call in the config
var final = []; //this is the final referred to in the config object
....
Baby.parse(data, args.config)
}
So the return next(null, final) and final.push(result) have to refer the the var / function in the new file, but I have no idea how to get that to work, that't why I had to add a final array in the config object and a null next function, then assign it like so:
exports.parse = function(args, next){
args.config.next = next;
....
Baby.parse(data, args.config)
}
the object was calling it with the ugly line:
return args.config.config.next(null, args.config.config.final);
If anyone has a way around this, it would be much appreciated.
If you use JSON.stringify with a "replacer" function and
JSON.parse with a "reviver" function along with new Function(), you can do it:
I'm not sure I'm following the second (updated) question you have. Once the object is parsed back into an object, why can't you just initialize the next and final properties to valid objects before calling any of the object's methods? You can even add tests into that method that checks for the existence of final and next before returning anything.
var myObj = {
next: null,
final:[],
delimiter: '~',
header: false,
step: function (row) {
var item = {
'line_code': row.data[0][0],
'order': row.data[0][1]
};
args.config.config.final.push(item);
},
complete: function (result) {
console.log('Reading data completed. Processing.');
return args.config.config.next(null, args.config.config.final);
},
error: function () {
console.log('There was an error parsing');
}
};
// Stringify the object using a replacer function that will explicitly
// turn functions into strings
var myObjString = JSON.stringify(myObj, function(key, val) {
return (typeof val === 'function') ? '' + val : val;
});
// Now, parse back into an object with a reviver function to
// test for function values and create new functions from them:
var obj = JSON.parse(myObjString, function(key, val){
// Make sure the current value is not null (is a string)
// and that the first characters are "function"
if(typeof val === "string" && val.indexOf('function') === 0){
// Isolate the argument names list
var start = val.indexOf("(") + 1;
var end = val.indexOf(")");
var argListString = val.substring(start,end).split(",");
// Isolate the body of the function
var body = val.substr(val.indexOf("{"), val.length - end + 1);
// Construct a new function using the argument names and body
// stored in the string:
return new Function(argListString, body);
} else {
// Non-function property, just return the value
return val;
}
}
);
// Test the method:
obj.error(); // 'There was an error parsing' is written to console.
// Examine the object:
console.log(obj);

MVC4 ModelState property name to JSON or Array

I am using a complex object graph serialized to JSON with MVC4/jQuery/Sammy/Rivets for SPA functionality.
I have a object graph that looks a bit like this when serialized to JSON (obviously mocked-up):
model =
{
Name: "Me",
Age: 22,
Hobbies:
[
{ Name: "Biking", IsActive: true },
{ Name: "Programming", IsActive: true }
]
}
Everything works quite well until I need Unobtrusive validation, since my Hobbies are in a SlickGrid and I am managing all the data myself. To handle this I am returning my ModelState with my JSON next to my model.
return JSON(new { model = model, modelState = this.ModelState });
From there I intend to iterate through the modelState and assign errors to the right place with some custom function, but there is one problem.
ModelState looks like this:
"Name",
"Age",
"Hobbies[0].Name",
"Hobbies[0].IsActive",
"Hobbies[1].Name",
"Hobbies[1].IsActive"
I need to separate the [0]'s into an object and [1]'s into their own objects so I can smoothly get the values. This gets confusing for me when I begin to account for a third level of complex object array.
Solution:
var ModelStateConverter = function ($, module) {
module = module || {};
// Convert The ModelState form style object to a standard JS object structure.
module.toObject = function (modelState) {
var ModelState = {};
$.each(modelState, function (key, value) {
AssignValuesToObjectStore(key, ModelState, value);
});
return ModelState;
}
// item is the full identifier ex. "Hobbies[0].Name"
// store is the object we are going to throw arrays, objects, and values into.
// value is the error message we want to get in the right place.
// index is an internal processing parameter for arrays only, setting it's value has no effect.
function AssignValuesToObjectStore(item, store, value, index) {
var periodMatch = item.match(/[\.]/);
if (periodMatch === null) {
if (Array.isArray(store)) {
if (store[index] === undefined) {
store[index] = {};
}
store[index][item] = value;
}
else {
store[item] = value;
}
}
else {
// This wasn't a simple property or end of chain.
var currentProperty = item.slice(0, periodMatch.index); // Get our property name up to the first period.
var container = {}; // We assume we are dealing with an object unless proven to be an array.
var arrayIndex; // This is irrelevant unless we have an array.
if (currentProperty.slice(-1, currentProperty.length) === "]") {
// We are dealing with an array! Hoo Ray?!
arrayIndex = parseInt(currentProperty.slice(currentProperty.indexOf("[") + 1, currentProperty.indexOf("]")));
currentProperty = currentProperty.slice(0, currentProperty.indexOf("[")); // remove the indexer ex. [0] so we are left with the real name
container = []; // We know we need an array instead;
}
if (store[currentProperty] === undefined) {
store[currentProperty] = container; // If this property isn't already created, then do so now.
}
//Recurseive nature here.
AssignValuesToObjectStore(item.slice(periodMatch.index + 1, item.length), store[currentProperty], value, arrayIndex);
}
}
return module;
}($, ModelStateConverter);
You can call this from:
ModelStateConverter.toObject(data.modelState);
Where data.modelState is assumed to be the ModelState from the server.
You could try a library like JSON.NET, or the class JavaScriptSerializer, to serialize the ModelState.

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