i have a webservice like this:
{"person":{"name account":"Jhon Doe","Image":"image/test","Adress":"New York 43","Recomendations":"40"}}
this is what i'm trying to do, when i print datos i get the whole json but when i try to print just the name or Image i don't get anything
var urll = "example.com/example";
var json;
var xhrr = Ti.Network.createHTTPClient({
onload: function() {
json = JSON.parse(this.responseText);
var datos = JSON.stringify(json);
var medicos = datos;
Ti.API.info("Json! "+datos);
}
});
xhrr.open('GET', urll);
xhrr.send();
i tried with datos[0].person, datos.person but nothing
You have to understand the difference between a string that contains a JSON representation of an object - and the object itself.
Your json variable contains the object (which is what JSON.parse(...) does - convert a text string to an object). On the object you can refer to the attributes as you discovered. You can do this in two ways:
json.person.Address
json.person['name account']
I would suggest that you try to avoid attributes with names that are not valid identifiers (as the latter of the two) as this makes it a little more difficult to use them - e.g. by not allowing the dot notation.
Your datos variable on the other hand contains the string representation of the json object (as JSON.stringify(...) does exactly that - convert an object to its string representation). This means that datos is the same as this.responseText (since you first parse it and then stringify it back).
So JSON.stringify(...) is a brilliant way to make the object "human readable" but you need the object to work with the data.
Hope this clarifies the terms a little ;-)
/John
i just find the solution:
Ti.API.info("Json! "+json.person.Recomendations);
Related
I am having output in following format as
"[{"a":"a1"},{"a":"a2"}]"
I want to actually extract it in array of json:
[
{
"a":"a1"
},
{
"a":"a2"
}
]
How to convert it?
You have tagged this with Node-RED - so my answer assumes that is the environment you are working in.
If you are passing a message to the Debug node and that is what you see in the Debug sidebar, that indicates your msg.payload is a String with the contents of [{"a":"a1"},{"a":"a2"}] - the Debug sidebar doesn't escape quotes when displaying strings like that.
So you likely already have exactly what you want - it just depends what you want to do with it next.
If you want to access the contents you need to parse it to a JavaScript Object. You can do this by passing your message through a JSON node.
Assuming your input contains the double quotes in the beginning and end, it is not possible to directly JSON.parse() the string.
In your case, you need to remove the first and last character (the double quotes) from your string before parsing it.
const unformattedString = '"[{"a":"a1"},{"a":"a2"}]"'
const formattedString = unformattedString.substr(1, unformattedString.length - 2)
const json = JSON.parse(formattedString)
The variable json now contains your JSON object.
I would suggest a different method which will get your work done without using any third party library.
var a = '[{"a":"a1"},{"a":"a2"}]';
var b = JSON.parse(a);
console.log(b); // b will return [{"a":"a1"},{"a":"a2"}]
Another way which is eval function which is generally not recommended
var d = eval(a);
If you want to use JQuery instead use :
var c = $.parseJSON(a);
I have a JSON file that contains what I believe to be a correct JSON string:
{"title": "exampleTitle", "tipTitle": "exampleTipTitle", "tip": "exampleTip"}
I'm trying to parse said file and take out the 3 values then store them in variables, however currently, it parses each individual character as a separate object, therefore:
JSONobj[1] = "
and so on. Assuming that currentLocation = the directory location of the json file.
Code
var jsonLocation = currentLocation + "json.txt";
var request = new XMLHttpRequest();
request.open("GET", jsonLocation, false);
request.send(null);
var returnValue = request.responseText;
var JSONobj = JSON.parse(JSON.stringify(returnValue));
var headerTitle = JSONobj[0];
A few clarifications, the stringify is in because it was throwing an unexpected token error. I've tried changing the file tile to .json instead but that also makes no difference. "It also gives off a XMLHttpRequest on the main thread is deprecated" but I'm not particularly sure how to solve that issue. Any help would be appreciated.
var returnValue = request.responseText;
Here returnValue is a string of JSON.
"{\"title\": \"exampleTitle\", \"tipTitle\": \"exampleTipTitle\", \"tip\": \"exampleTip\"}
var JSONobj = JSON.parse(JSON.stringify(returnValue));
Here you convert the string of JSON to JSON. So you have a JSON string representing a string, and that string is a representation of a data structure in JSON.
"\"{\\"title\\": \\"exampleTitle\\", \\"tipTitle\\": \\"exampleTipTitle\\", \\"tip\\": \\"exampleTip\\"}"
Then you parse it and convert it back to the original string of JSON.
"{\"title\": \"exampleTitle\", \"tipTitle\": \"exampleTipTitle\", \"tip\": \"exampleTip\"}
So you end up back where you start.
Just don't use JSON.stringify here, and you'll convert your JSON to a JavaScript object:
var javascript_object = JSON.parse(returnValue);
Then you have an object, but it doesn't have a 0 property so it doesn't make sense to access it with javascript_object[0]. The properties have names, such as javascript_object.title.
Your JSON doesn't describe an array, so indexing into it with an index like 0 doesn't make sense. Your JSON describes an object, which will have properties with the names title, tipTitle, and tip.
Additionally, you're overdoing your parsing: You just want to parse, not stringify (which is the opposite of parsing):
var JSONobj = JSON.parse(returnValue);
So:
var JSONobj = JSON.parse(returnValue);
var headerTitle = JSONobj.title;
console.log(headerTitle); // "exampleTitle"
Side note: By the time you've assigned it to the variable you've called JSONobj, it isn't JSON anymore, it's just a normal JavaScript object, so that name is a bit misleading. If you're writing source code, and you're not dealing with a string, you're not dealing with JSON anymore. :-)
This question is multipart-
(1a) JSON is fundamental to JavaScript, so why is there no JSON type? A JSON type would be a string that is formatted as JSON. It would be marked as parsed/stringified until the data was altered. As soon as the data was altered it would not be marked as JSON and would need to be re-parsed/re-stringified.
(1b) In some software systems, isn't it possible to (accidentally) attempt to send a plain JS object over the network instead of a serialized JS object? Why not make an attempt to avoid that?
(1c) Why can't we call JSON.parse on a straight up JavaScript object without stringifying it first?
var json = { //JS object in properJSON format
"baz":{
"1":1,
"2":true,
"3":{}
}
};
var json0 = JSON.parse(json); //will throw a parse error...bad...it should not throw an error if json var is actually proper JSON.
So we have no choice but to do this:
var json0= JSON.parse(JSON.stringify(json));
However, there are some inconsistencies, for example:
JSON.parse(true); //works
JSON.parse(null); //works
JSON.parse({}); //throws error
(2) If we keep calling JSON.parse on the same object, eventually it will throw an error. For example:
var json = { //same object as above
"baz":{
"1":1,
"2":true,
"3":{}
}
};
var json1 = JSON.parse(JSON.stringify(json));
var json2 = JSON.parse(json1); //throws an error...why
(3) Why does JSON.stringify infinitely add more and more slashes to the input? It is not only hard to read the result for debugging, but it actually puts you in dangerous state because one JSON.parse call won't give you back a plain JS object, you have to call JSON.parse several times to get back the plain JS object. This is bad and means it is quite dangerous to call JSON.stringify more than once on a given JS object.
var json = {
"baz":{
"1":1,
"2":true,
"3":{}
}
};
var json2 = JSON.stringify(json);
console.log(json2);
var json3 = JSON.stringify(json2);
console.log(json3);
var json4 = JSON.stringify(json3);
console.log(json4);
var json5 = JSON.stringify(json4);
console.log(json5);
(4) What is the name for a function that we should be able to call over and over without changing the result (IMO how JSON.parse and JSON.stringify should behave)? The best term for this seems to be "idempotent" as you can see in the comments.
(5) Considering JSON is a serialization format that can be used for networked objects, it seems totally insane that you can't call JSON.parse or JSON.stringify twice or even once in some cases without incurring some problems. Why is this the case?
If you are someone who is inventing the next serialization format for Java, JavaScript or whatever language, please consider this problem.
IMO there should be two states for a given object. A serialized state and a deserialized state. In software languages with stronger type systems, this isn't usually a problem. But with JSON in JavaScript, if call JSON.parse twice on the same object, we run into fatal exceptions. Likewise, if we call JSON.stringify twice on the same object, we can get into an unrecoverable state. Like I said there should be two states and two states only, plain JS object and serialized JS object.
1) JSON.parse expects a string, you are feeding it a Javascript object.
2) Similar issue to the first one. You feed a string to a function that needs an object.
3) Stringfy actually expects a string, but you are feeding it a String object. Therefore, it applies the same measures to escape the quotes and slashes as it would for the first string. So that the language can understand the quotes, other special characters inside the string.
4) You can write your own function for this.
5) Because you are trying to do a conversion that is illegal. This is related to the first and second question. As long as the correct object types are fed, you can call it as many times as you want. The only problem is the extra slashes but it is in fact the standard.
We'll start with this nightmare of your creation: string input and integer output.
IJSON.parse(IJSON.stringify("5")); //=> 5
The built-in JSON functions would not fail us this way: string input and string output.
JSON.parse(JSON.stringify("5")); //=> "5"
JSON must preserve your original data types
Think of JSON.stringify as a function that wraps your data up in a box, and JSON.parse as the function that takes it out of a box.
Consider the following:
var a = JSON.stringify;
var b = JSON.parse;
var data = "whatever";
b(a(data)) === data; // true
b(b(a(a(data)))) === data; // true
b(b(b(a(a(a(data)))))) === data; // true
That is, if we put the data in 3 boxes, we have to take it out of 3 boxes. Right?
If I put my data in 2 boxes and take it out of 1, I'm not holding my data yet, I'm holding a box that contains my data. Right?
b(a(a(data))) === data; // false
Seems sane to me...
JSON.parse unboxes your data. If it is not boxed, it cannot unbox it. JSON.parse expects a string input and you're giving it a JavaScript object literal
The first valid call to JSON.parse would return an object. Calling JSON.parse again on this object output would result in the same failure as #1
repeated calls to JSON.stringify will "box" our data multiple times. So of course you have to use repeated calls to JSON.parse then to get your data out of each "box"
Idempotence
No, this is perfectly sane. You can't triple-stamp a double-stamp.
You'd never make a mistake like this, would you?
var json = IJSON.stringify("hi");
IJSON.parse(json);
//=> "hi"
OK, that's idempotent, but what about
var json = IJSON.stringify("5");
IJSON.parse(json);
//=> 5
UH OH! We gave it a string each time, but the second example returns an integer. The input data type has been lost!
Would the JSON functions have failed us here?
var json = JSON.stringify("hi");
JSON.parse(json);
//=> "hi"
All good. And what about the "5" ?
var json = JSON.stringify("5");
JSON.parse(json));
//=> "5"
Yay, the types have been preseved! JSON works, IJSON does not.
Maybe a more real-life example:
OK, so you have a busy app with a lot of developers working on it. It makes
reckless assumptions about the types of your underlying data. Let's say it's a chat app that makes several transformations on messages as they move from point to point.
Along the way you'll have:
IJSON.stringify
data moves across a network
IJSON.parse
Another IJSON.parse because who cares? It's idempotent, right?
String.prototype.toUpperCase — because this is a formatting choice
Let's see the messages
bob: 'hi'
// 1) '"hi"', 2) <network>, 3) "hi", 4) "hi", 5) "HI"
Bob's message looks fine. Let's see Alice's.
alice: '5'
// 1) '5'
// 2) <network>
// 3) 5
// 4) 5
// 5) Uncaught TypeError: message.toUpperCase is not a function
Oh no! The server just crashed. You'll notice it's not even the repeated calling of IJSON.parse that failed here. It would've failed even if you called it once.
Seems like you were doomed from the start... Damned reckless devs and their careless data handling!
It would fail if Alice used any input that happened to also be valid JSON
alice: '{"lol":"pwnd"}'
// 1) '{"lol":"pwnd"}'
// 2) <network>
// 3) {lol:"pwnd"}
// 4) {lol:"pwnd"}
// 5) Uncaught TypeError: message.toUpperCase is not a function
OK, unfair example maybe, right? You're thinking, "I'm not that reckless, I
wouldn't call IJSON.stringify or IJSON.parse on user input like that!"
It doesn't matter. You've fundamentally broken JSON because the original
types can no longer be extracted.
If I box up a string using IJSON, and then unbox it, who knows what I will get back? Certainly not you, and certainly not the developer using your reckless function.
"Will I get a string type back?"
"Will I get an integer?"
"Maybe I'll get an object?"
"Maybe I will get cake. I hope it's cake"
It's impossible to tell!
You're in a whole new world of pain because you've been careless with your data types from the start. Your types are important so start handling them with care.
JSON.stringify expects an object type and JSON.parse expects a string type.
Now do you see the light?
I'll try to give you one reason why JSON.parse cannot be called multiple time on the same data without us having a problem.
you might not know it but a JSON document does not have to be an object.
this is a valid JSON document:
"some text"
lets store the representation of this document inside a javascript variable:
var JSONDocumentAsString = '"some text"';
and work on it:
var JSONdocument = JSON.parse(JSONDocumentAsString);
JSONdocument === 'some text';
this will cause an error because this string is not the representation of a JSON document
JSON.parse(JSONdocument);
// SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data
in this case how could have JSON.parse guessed that JSONdocument (being a string) was a JSON document and that it should have returned it untouched ?
I want to store the result from a call to a Domino Access Service (DAS) in a localStorage however when I try to convert the result object to a JSON string I get an error.
With DAS you get the result as an Array e.g.:
[
{
"#entryid":"1-CD90722966A36D758025725800726168",
"#noteid":"16B46",
Does anyone know how I get rid of the square brackets or convert the Array quickly to a JSON object?
Here is a snippet of my code:
var REST = "./myREST.xsp/notesView";
$.getJSON(REST,function(data){
if(localStorage){
localStorage.setItem('myCatalog',JSON.stringify(data));
}
});
Brackets are part of the JSON syntax. They indicate that this is an array of objects. And as you point to a view it is very likely that you would get more than one object back (one for each entry in the view).
So if you are only interested in the first element you could do this:
var REST = "./myREST.xsp/notesView";
$.getJSON(REST,function(data){
if(localStorage){
var firstRecord = data[0] || {};
localStorage.setItem('myCatalog',JSON.stringify(firstRecord));
}
});
Otherwise, you would need to define a loop to handle each of the objects :-)
/John
what is the difference between json string and parsed json string?
for eg in javascript suppose i have a string in the json format say [{},{}]
parsing this string will also produce the same thing.
So why do we need to parse?
It's just serialization/deserialization.
In Javscript code you normally work with the object, as that lets you easily get its properties, etc, while a JSON string doesn't do you much good.
var jsonobj = { "arr": [ 5, 2 ], "str": "foo" };
console.log(jsonobj.arr[1] + jsonobj.str);
// 2foo
var jsonstr = JSON.stringify(jsonobj);
// cannot do much with this
To send it to the server via an Ajax call, though, you need to serialize (stringify) it first. Likewise, you need to deserialize (parse) from a string into an object when receiving JSON back from the server.
Great question. The difference is transfer format.
JSON is only the 'Notation' of a JavaScript Object, it is not actually the JavaScript 'object-literal' itself. So as the data is received in JSON, it is just a string to be interpreted, evaluated, parsed, in order to become an actual JavaScript 'Object-Literal.
There is one physical difference between the two, and that is quotation marks. It makes sense, that JSON needs to be a string to be transferred. Here is how:
//A JavaScript Object-Literal
var anObj = { member: 'value'}
//A JSON representation of that object
var aJSON = { "member":"value" }
Hope that helps. All the best! Nash
I think a parsed json string should be the string data into the actual javascript objects and data arrays (or whichever language the json string contains)
The JSON object contains methods for parsing JSON and converting values to JSON.
It can't be called or constructed, and aside from its two method properties it has no interesting functionality of its own.
JSONParser parser = new JSONParser();
Object object = parser.parse(Message.toString());
JSONObject arObj = (JSONObject) object;