I am working on a Node.js application that needs to handle JSON strings and work with the objects.
Mostly all is well and JSON.parse(myString) is all I need.
The application also gets data from third parties. One of which seems to be developed with Python.
My application repeatable chokes on boolean values since they come captialized.
Example:
var jsonStr = "{'external_id': 123, 'description': 'Run #2944', 'test_ok': False}";
try{
var jsonObj = JSON.parse(jsonStr);
}catch(err){
console.err('Whoops! Could not parse, error: ' + err.message);
}
Notice the test_ok parameter - it all is good when it follows the Javascript way of having a lower case false boolean instead. But the capitalized boolean does not work out.
Of course I could try and replace capitalized boolean values via a string replace, but I am afraid to alter things that should not get altered.
Is there an alternative to JSON.parse that is a little more forgiving?
I don't mean to be rude but according to json.org, its an invalid json. That means you'll have to run a hack where you have to identify stringified boolean "True" and convert it to "true" without affecting a string that lets say is "True dat!"
First of all, I would not recommend using the code below. This is just to demonstrate how to convert your input string into a valid JSON. There were problems, one is the Boolean False, and another is the single quotes around property names. I'm not positive but I believe those need to be double quotes.
I don't believe having to convert a string into a valid JSON is a good choice. If you have no alternative, meaning you don't have access to the code generating this string, then the code below is still not a good choice because it will have issues if you have embedded quotes in the string values. i.e. you would need different string replace logic.
Keep all this in mind before using the code.
var jsonStr = "{'external_id': 123, 'description': 'Run #2944', 'test_ok': False}";
try {
jsonStr = jsonStr.replace(/:[ ]*False/,':false' ).replace( /'/g,'"');
var jsonObj = JSON.parse(jsonStr);
console.log( jsonObj );
} catch (err) {
console.err('Whoops! Could not parse, error: ' + err.message);
}
Related
Consider the following event payload data returned via WS:
{
id: "1",
foo: "{"bar":"baz"}"
}
The current output of JSON.stringify(event.foo):
"{\"bar\":\"baz\"}"
Also consider the backend have no real way to return the foo value formatted differently and I need to find a way to parse the string associated to this foo key in order to access it's value of bar.
The identified problem is the fact that the quotes used to wrap the whole supposed object are the sames used in the object itself, resulting in making JSON.parse() impossible.
I'm wondering if there is a "clean" way to achieve this.
So far, I tried:
using JSON.parse() which fails due to the format of the string raising Unexpected end of JSON input
trimming external quotes and converting inner ones to single then parsing, results in same error.
using new Object(...) based on the string (trimmed of external quotes)
replacing all quotes with single ones and wrapping it again in double ones to parse it.
Any input appreciated
The problem here is the backend should really be fixed, but some reason you can not do it. Next issue is you can "fix it" on the front end, but you are putting a band aid on the problem and it will fall off when the data that comes back is not what you expect. So the solutions will be error prone unless you know the data coming back will be a specific type.
With this said, you can fix the invalid JSON that you have in your simple example with a couple of regular expressions. Problem is, if your data contains characters such as } in the text, this is going to fail.
var response = `
{
id: "1",
foo: "{"bar":"baz"}",
goo: "{"gar":"gaz"}"
}
`
var reObj = /"(\{[^}]*})"/
while (response.match(reObj)) {
response = response.replace(reObj, '$1')
}
var reKey = /^\s+(\S+):/m
while (response.match(reKey)) {
response = response.replace(reKey,'"$1":')
}
var obj = JSON.parse(response)
console.log(obj)
I have a site and I used AJAX. And I got some problems.
Server return JSON string something like this {a:"x48\x65\x6C\x6C\x6F"}.
Then in xx.responseText, we have this string '{a:"\x48\x65\x6C\x6C\x6F"}'.
But if I create JavaScript string "\x48\x65\x6C\x6C\x6F" then I have "Hello" and not HEX!
Is it possible get in xx.responseText "real" text from HEX (automatically, without .replace())?
If the output is at all regular (predictable), .replace() is probably the simplest.
var escapeSequences = xx.responseText.replace(/^\{a:/, '').replace(/\}$/, '');
console.log(escapeSequences === "\"\\x48\\x65\\x6C\\x6C\\x6F\""); // true
Or, if a string literal that's equivalent in value but may not otherwise be the same is sufficient, you could parse (see below) and then stringify() an individual property.
console.log(JSON.stringify(data.a) === "\"Hello\""); // true
Otherwise, you'll likely need to run responseText through a lexer to tokenize it and retrieve the literal from that. JavaScript doesn't include an option for this separate from parsing/evaluating, so you'll need to find a library for this.
"Lexer written in JavaScript?" may be a good place to start for that.
To parse it:
Since it appears to be a string of code, you'll likely have to use eval().
var data = eval('(' + xx.responseText + ')');
console.log(data.a); // Hello
Note: The parenthesis make sure {...} is evaluated as an Object literal rather than as a block.
Also, I'd suggest looking into alternatives to code for communicating data like this.
A common option is JSON, which takes its syntax from JavaScript, but uses a rather strict subset. It doesn't allow functions or other potentially problematic code to be included.
var data = JSON.parse(xx.responseText);
console.log(data.a); // Hello
Visiting JSON.org, you should be able to find a reference or library for the choice of server-side language to output JSON.
{ "a": "Hello" }
Why not just let the JSON parser do its job and handle the \x escape sequences, and then just convert the string back to hex again afterwards, e.g.
function charToHex(c) {
var hex = c.charCodeAt(0).toString(16);
return (hex.length === 2) ? hex : '0' + hex;
}
"Hello".replace(/./g, charToHex); // gives "48656c6c6f"
I am being sent an ill formed JSON string from a third party. I tried using JSON.parse(str) to parse it into a JavaScript object but it of course failed.
The reason being is that the keys are not strings:
{min: 100}
As opposed to valid JSON string (which parses just fine):
{"min": 100}
I need to accept the ill formed string for now. I imagine forgetting to properly quote keys is a common mistake. Is there a good way to change this to a valid JSON string so that I can parse it? For now I may have to parse character by character and try and form an object, which sounds awful.
Ideas?
You could just eval, but that would be bad security practice if you don't trust the source. Better solution would be to either modify the string manually to quote the keys or use a tool someone else has written that does this for you (check out https://github.com/daepark/JSOL written by daepark).
I did this just recently, using Uglifyjs to evaluate:
var jsp = require("uglify-js").parser;
var pro = require("uglify-js").uglify;
var orig_code = "var myobject = " + badJSONobject;
var ast = jsp.parse(orig_code); // parse code and get the initial AST
var final_code = pro.gen_code(ast); // regenerate code
$('head').append('<script>' + final_code + '; console.log(JSON.stringify(myobject));</script>');
This is really sloppy in a way, and has all the same problems as an eval() based solution, but if you just need to parse/reformat the data one time, then the above should get you a clean JSON copy of the JS object.
Depending on what else is in the JSON, you could simply do a string replace and replace '{' with '{"' and ':' with '":'.
I have a variable called "result",
var result;
that result value is equal to following value, please presume that is just a string :)
---------result value -----------
for (;;);{
"send":1,
"payload":{
"config":{
"website":"",
"title":"welcome to site",
"website-module":1313508674538,
"manufatureid":"id.249530475080015",
"tableid":"id.272772962740259",
"adminid":100002741928612,
"offline":null,
"adminemail":"admin#website.com",
"adminame":"George",
"tags":"web:design:template",
"source":"source:design:web",
"sitelog":[],
"errorlog":0,
"RespondActionlog":0,
"map":null
},
"imgupload":""
},
"criticalerror":[0],
"report":true
}
---------result value------------
From that value, I would like to extract tableid which is "id.272772962740259" with classic Javascript.
How can I extract the code, please let me know how can i do with simple javascript, please don't use Jquery, all I just need is simple javascript.
You can simply evaluate the value of the variable to obtain the values. However, please note that your current value is not valid JSON; that for(;;); at the beginning of the value invalidates the format. Remove that, and you can do this:
var object = eval('(' + resultMinusThatForLoop + ')');
alert(object.payload.config.tableid);
If that data is a string the parse it with a JSON parse. The following should get the value you want
JSON.parse(result).payload.config.tableid; // "id.272772962740259"
Edit: though, as Tejs says, the for(;;) invalidates the string and stops it from being parsed. If you can remove that, do.
You need to remove the empty for loop, then parse the string. DO NOT use eval; most modern browsers provide built-in JSON-parsing facilities, but you can use json2.js if yours does not. Assuming that you assign the results of parsing the JSON to result, you should be able to get that value using result.payload.config.tableid.
You should probably read a good JS reference. JavaScript: The Good Parts or Eloquent JavaScript would be a good choice.
If result is a javascript object and not a string, you can just use 'result.payload.config.tableid'.
If it is not, how do you get the AJAX result? Are you using XmlHttpRequest directly? Most libraries will give you a javascript object, you might be missing a flag or not sending the response back with the right content type.
If it is a string and you want to parse it manually, you should use a JSON parser. Newer browsers have one built in as window.JSON, but there is open source code for parsing it as well.
var obj = JSON.parse(result);
alert('tableid is ' + obj.payload.config.tableid);
I am parsing a json string like so:
ring = JSON.parse(response);
Now, ring is an object but ring.stones is just a string when it should be an object as well.
If I call:
ring.stones = JSON.parse(ring.stones);
It is now the correct object.
I didn't know if this is correct behavior or if maybe I have an issue somewhere stopping it from parsing recursively? If it is supposed to parse recursively, are there any known issues that would prevent it?
Update
Here is the full response before parsing:
{"ring_id":"9","stone_count":"4","style_number":"style 4","syn10":"436.15","gen10":"489.39","syn14":"627.60","gen14":"680.85","available":"yes","type":"ring","engravings_count":"0","engravings_char_count":"0","engravings_band":"10","stones":"[{\"stone_id\":\"27\",\"ring_id\":\"9\",\"stone_shape\":\"round\",\"stone_x\":\"132.80\",\"stone_y\":\"114.50\",\"stone_width\":\"71.60\",\"stone_height\":\"71.60\",\"stone_rotation\":\"0.00\",\"stone_number\":\"1\",\"stone_mm_width\":\"5.00\",\"stone_mm_height\":\"5.00\"},{\"stone_id\":\"28\",\"ring_id\":\"9\",\"stone_shape\":\"round\",\"stone_x\":\"100.50\",\"stone_y\":\"166.20\",\"stone_width\":\"36.20\",\"stone_height\":\"36.60\",\"stone_rotation\":\"0.00\",\"stone_number\":\"2\",\"stone_mm_width\":\"2.50\",\"stone_mm_height\":\"2.50\"},{\"stone_id\":\"29\",\"ring_id\":\"9\",\"stone_shape\":\"round\",\"stone_x\":\"200.20\",\"stone_y\":\"105.10\",\"stone_width\":\"33.90\",\"stone_height\":\"33.90\",\"stone_rotation\":\"0.00\",\"stone_number\":\"3\",\"stone_mm_width\":\"2.50\",\"stone_mm_height\":\"2.50\"},{\"stone_id\":\"30\",\"ring_id\":\"9\",\"stone_shape\":\"round\",\"stone_x\":\"165.80\",\"stone_y\":\"82.50\",\"stone_width\":\"35.50\",\"stone_height\":\"33.90\",\"stone_rotation\":\"0.00\",\"stone_number\":\"4\",\"stone_mm_width\":\"2.50\",\"stone_mm_height\":\"2.50\"}]","images":"[{\"title\":\"white gold\",\"source\":\"Style4_4_W_M.png\"},{\"title\":\"yellow gold\",\"source\":\"Style4_4_Y_M.png\"}]"}
Update 2
Based on mikerobi's answer I was able to figure out what was happening:
Here is where I encoded it:
$row = $sth->fetch(PDO::FETCH_ASSOC);
$row['stones'] = getStones($ring_id);
$row['images'] = getRingVariations($ring_id);
return json_encode($row);
But the functions getStones and getRingVariations were returning json_encode'd strings. I needed to change them to return plain strings.
Your JSON structure is wrong, it is wrapping stones in quotes, turning it into a string.
Your JSON looks like:
{
stones: "[{\"stone_id":\"27\"},{\"stone_id\":\"27\"}]"
}
It should look like:
{
stones: [{"stone_id": 27},{"stone_id": 27}]
}
EDIT
It appears you are converting all values to string, including numbers, I updated my example to reflect this.
Also, I'm guessing by the output that you are writing your own code to serialize the JSON, I highly recommend using an existing library.
It is recursive, but your input string (response) is not in correct format. Get rid of those escape characters (\") and try again.