Complex JSON string Parsing in JavaScript - javascript

This is my sample JSON file , which im trying to parse and read the values ....
C = {{
"Travel": {
"ServiceProvider": {
"Name": "SRS",
"Rating": "3 stars",
"Rates": "Nominal",
"Features": {
"OnlineBooking": "Yes",
"SMS_Ticket": "No"
},
"UserDetails": {
"Name": "Jack",
"Age": "33",
"Gender": "Male"
}
},
"BusProvider": {
"Name": "SRS",
"Rating": "3 stars",
"Rates": "Nominal",
"Features": {
"OnlineBooking": "Yes",
"SMS_Ticket": "No"
},
"UserDetails": {
"Name": "Jack",
"Age": "33",
"Gender": "Male"
}
}
}
}
I'm pretty new to JS , and i need to access the nested elements in a generic fashion.
Im not able to extract the details properly. Im getting stuck accessing nested the child elements.
The problem for me is that i wont always know the names of the "key's' to acess them , the JSON will be dynamic , hence i need a generic mechanism to acess the nested child elements. The Nesting can go upto 3 -4 levels.
what notation do we use to access the key / value pairs when the nesting is deep.
Any Help would be appreciated.

ater desirializing your object you can do this
var resultJSON = '{"name":"ricardo","age":"23"}';
var result = $.parseJSON(resultJSON);
$.each(result, function(k, v) {
//display the key
alert(k + ' is the key)
}
you can do it using recursively offcourse like this - Link Here
the way is the same just adapt to your example

For dynamic access you can use brackets notation i.e. var json = {nonKnown: 1}; now you can access it like that:
var unknowPropertyName = "nonKnown";
var value = json[unknownPropertyName];
But if you can not even define dynamically name of the property, then you should use
for(variableName in json){
if(json.hasOwnProperty(variableName)){
console.log(variableName);
}
}
You should get the basic idea from this. Good luck

Related

How do you index incomplete strings to JSON keys?

I would like to be able to type in "Hammerhead" to call the "Hammerhead Shark" object without its full name. Is this possible and if so how?
I tried using array.indexOf(string) though it doesn't really seem to help since it requires an exact match such as typing "Hammerhead Shark"
JS:
const JSON = require('animals.json');
var animals = Object.keys(JSON);
if (animals.indexOf("Hammerhead")) {
console.log(JSON["Hammerhead"].name);
}
JSON:
{
"Hammerhead Shark": {
"name": "Shark",
"age": "300"
},
"Duck": {
"name": "Duck",
"age": "1000"
}
}
I expect the output to be "Shark" instead of undefined.
It seems you want to get access the value in object. By its partial name.
Get the entries of object using Object.entries()
Find the key which includes() the given partial key.
return the second element of the found entry.
const obj = { "Hammerhead Shark": { "name": "Shark", "age": "300" }, "Duck": { "name": "Duck", "age": "1000" } }
function getValueByPartialKey(obj,key){
return (Object.entries(obj).find(([k,v]) => k.includes(key)) || [])[1]
}
console.log(getValueByPartialKey(obj,"Hammerhead"))
You can use string.includes(word) to return the name that matches the string that you're searching for, along with Array.filter iterates over the values too, and returns the result(s) you want.

Search in json file with Node JS

I have several objects like this and wonder how I can search between these, say that we got the number 1 and want to figure out what the name is.
Should I loop it or what do you guys suggest?
To make things clear, I do want to get the other objects by using the number. Is it possible?
{
"room": [
{
"number": "1",
"name": "room1"
},
{
"number": "2",
"name": "room2"
}
]
}
You could use a map and use the room number as identifier. This way you can access the room data via the room number like that:
var data = {
"room": [
{
"number": "1",
"name": "room1"
},
{
"number": "2",
"name": "room2"
}
]
};
// or load it from a file:
// var data = require('./data.json');
var rooms = new Map();
for(room of data.room) {
rooms.set(Number(room.number), room);
}
// access data for room with number 1
alert(rooms.get(1).name);
Firstly, bring in the file. Make sure to include the './' before the file name to show that it's from the current directory.
const data = require('./data.json');
Now the JSON data is stored inside the variable data. To access the members, use the dot operator. data.room will return the array of rooms.
To access the individual room, use data.room[i] where i is the numbered element in the array (starting from 0). For example, to access the first room:
const first_room = data.room[0];
This first_room variable can now be used to access the name.
console.log(first_room.name);
This will log "room1" to the console.
You can try this. This will help you.
var roomData = {
"room": [
{
"number": "1",
"name": "room1"
},
{
"number": "2",
"name": "room2"
}
]
}
for(key in roomData.room){
console.log("Room Number - " + roomData.room[key].number);
console.log("Room Name - " + roomData.room[key].name);
}

JSON list optimization

I want to create a JSON API that returns a list of objects. Each object has an id, a name and some other information. API is consumed using JavaScript.
The natural options for my JSON output seems to be:
"myList": [
{
"id": 1,
"name": "object1",
"details": {}
},
{
"id": 2,
"name": "object2",
"details": {}
},
{
"id": 3,
"name": "object3",
"details": {}
},
]
Now let's imagine that I use my API to get all the objects but want to first do something with id2 then something else with id1 and id3.
Then I may be interested to be able to directly get the object for a specific id:
"myList": {
"1": {
"name": "object1",
"details": {}
},
"2": {
"name": "object2",
"details": {}
},
"3": {
"name": "object3",
"details": {}
},
}
This second option may be less natural when somewhere else in the code I want to simply loop through all the elements.
Is there a good practice for these use cases when the API is used for both looping through all elements and sometime using specific elements only (without doing a dedicated call for each element)?
In your example you've changed the ID value from 1 to id1. This would make operating on the data a bit annoying, because you have to add and remove id all the time.
If you didn't do that, and you were relying on the sorted order of the object, you may be in for a surprise, depending on JS engine:
var source = JSON.stringify({z: "first", a: "second", 0: "third"});
var parsed = JSON.parse(source);
console.log(Object.keys(parsed));
// ["0", "z", "a"]
My experience is to work with arrays on the transport layer and index the data (i.e. convert array to map) when required.

Can a JSON array contain objects of different key/value pairs?

Can a JSON array contain Objects of different key/value pairs. From this tutorial, the example given for JSON array consists of Objects of the same key/value pair:
{
"example": [
{
"firstName": "John",
"lastName": "Doe"
},
{
"firstName": "Anna",
"lastName": "Smith"
},
{
"firstName": "Peter",
"lastName": "Jones"
}
]
}
If I want to change it to have different key/value pairs inside the JSON array, is the following still a valid JSON?
{
"example": [
{
"firstName": "John",
"lastName": "Doe"
},
{
"fruit": "apple"
},
{
"length": 100,
"width": 60,
"height": 30
}
]
}
Just want to confirm this. If so, how can I use JavaScript to know if the JSON "example" field contains the first homogeneous objects or the second heterogeneous objects?
You can use any structure you like. JSON is not schema based in the way XML is often used and Javascript is not statically typed.
you can convert your JSON to a JS object using JSON.parse and then just test the existence of the property
var obj = JSON.parse(jsonString);
if(typeof obj.example[0].firstName != "undefined") {
//do something
}
It doesn't matter you can mix and match as much as you want.
You could just test it
typeof someItem.example !== 'undefined' // True if `example` is defined.
It's perfectly valid JSON. Personally I prefer this syntax better, because it reads easier:
{
"example": [
{
"firstName": "John",
"lastName": "Doe"
},
{
"fruit": "apple"
},
{
"length": 100,
"width": 60,
"height": 30
}
]
}
As to answer your second question, you can read data from a JSON string by using var data = JSON.parse(datastring);. Then simply use it by calling data.property.secondlevel. Any variable can be an object, array, string or number, allowing for nested structures.
You are free to do what you want with the contents of the array. Jus remember about this before you try to iterate an access properties of each item in your array.
one thing: you won't be able to deserialize this to anything else than an array of object in your server side, so don't have surprises later.
as a hint, maybe you could include a common field in the objects specifying the "type" so later is easy to process.
var array = [{"type":"fruit", "color":"red"},
{"type":"dog", "name":"Harry"}];
var parser = {
fruit:function(f){
console.log("fruit:" + f.color);
},
dog: function(d){
console.log("dog:"+d.name);
}};
for(var i=0;i<array.length;i++){
parser[array[i].type](array[i]);
}

How to search and select an object in JSON

Consider a JSON like this:
[{
"type": "person",
"name": "Mike",
"age": "29"
},
{
"type": "person",
"name": "Afshin",
"age": "21"
},
{
"type": "something_else",
"where": "NY"
}]
I want to search in the JSON value with a key (for example type='person') and then select a whole object of matched item in JSON. For example when I search for type='person' I expect this value:
[{
"type": "person",
"name": "Mike",
"age": "29"
},
{
"type": "person",
"name": "Afshin",
"age": "21"
}]
Because it's a really big JSON value, I don't want to do a brute-force search in all nodes, so I think the only way is using Regular Expressions but I don't know how can I write a Regex to match something like above.
I'm using NodeJs for the application.
Using underscore.js#where:
var results = _(yourObject).where({ type: 'person' })
If your data set is very very big [e.g. 10k or so], consider filtering / paginating stuff server side.
Plain javascript :
var results = dataset.filter(function(p) {
if(p.type == 'person')
return true;
});
If the requirement is to scan multiple times through the collection, the following one time construction overhead might be of worth.
Use hashing based on values of type.Convert the current data structure to hash map.
var hashMap ={
};
hashMap['person'] =[{},{}];
Hope this helps you.
Use
$.grep(jsonarrayobj,function(n, i){
if(n.type==="person")
{}
})

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