I am using node-RED to call in data from a robot. In the debug window it says it is a 'msg: Object', and when I copy it to a notepad it takes the format: {"topic":"","payload":27.659992218017578,"_session":{"type":"tcp","id":"0151ff7339437ec6"},"_msgid":"6a6897605a523366"}
I am also not sure if this is a JSON object or not, as I see examples with '' around the brackets.
I am trying to use the function node within node-red to parse this to attain the "payload" value. However, it keeps returning as undefined.
I am using the script:
var json =msg.payload;
var obj = JSON.parse(json);
msg.payload = console.log(obj.payload);
return msg;
I am a beginner to javascript and JSON, however I have tried searching and all examples only have integers as the parsing value. I am also unsure if the value name itself 'payload' is causing an issue. I have also attempted to stringify and using 'getDouble' but had no luck, which I owe to my lack of experience.
I appreciate any guidance.
You don't need to do anything. The value of msg.payload is already a double.
Without a lot more context of what you are trying to do there isn't anything else that we can say here.
After the node that gets the above information (the data in {} in the question}, I then used the function node to construct the message that I wanted to sent to the IIOT platform. I did
const str = msg.payload
msg.payload = " ," + str
// where the text I required was in " "
return msg
Also this works:
msg.payload = "," + msg.payload
return msg
And then I used the MQTT output node to publish this to the IIOT platform
Related
So I am trying to create a JSON explorer / editor. I am able to parse the initial JSON into the div and format it how I like.
this is the function i use to loop through the initial JSON
_iterate(_tab, raw_json){
var tab = _tab;
tab++;
for(var key1 in raw_json){
var data_type = typeof raw_json[key1];
var d = String(raw_json[key1])
if(d == String){
d = "String";
}
if(d == Number){
d= "Number"
}
if(data_type == "object" || data_type == "array"){
this.input.append(`<json-tab tab-width="${tab}"></json-tab><div class="json-editor-input-container-2 -je-${data_type}">'<span class="-je-key">${key1}</span>' :{</div></br>`)
this._iterate(tab, raw_json[key1])
}else{
this.input.append(`<div class="json-editor-row"><json-tab tab-width="${tab}"></json-tab><div class="json-editor-input-container-2">'<span class="-je-key">${key1}<span>' : '<div class="json-editor-input -je-${data_type}" contenteditable="true" for="{key: '${key1}', data: '${d}'}"></div>', </div></br></div>`)
}
}
this.input.append(`<json-tab tab-width="${tab -1}"></json-tab>},</br>`)
}
in order to save the JSON I was going to retrieve the JSON from the text of the div using
getJSON(){
var json_text = this.input.text().slice(0, -1)
return JSON.parse(`"${json_text}"`)
}
right now this is able to be parse by JSON.parse(); but when i want to console.log(getJSON()[0]) this returns {
am i not formating the JSON correctly. a live example of this can be found here
First, your console.log result doesn't make sense. A parsed JSON object is now usable in JavaScript and, if has (only) properties x and y, would result in undefined when requesting property 0 as you have. It looks like your call to console.log was to a different (earlier?) version of the getJSON() function, where it returned the raw string, and in that case it makes sense that you're just retrieving the first character of the JSON text: "{".
But then, assuming the version of getJSON() as written, it would actually throw a parse exception:
VM1511:1 Uncaught SyntaxError: Unexpected token ' in JSON at position 1
Looking at your site, I was able to do, in the console:
jsonString = $('json-editor').text()
// value: "{'partName' : '', 'partRevision' : '', ..."
That is illegal JSON. JSON specifies (only) the quotation mark " for strings (Unicode/ASCII 0x22) on page 7 of its specification.
The fact that 'partName' is legal as a JavaScript string literal is irrelevant but perhaps confusing.
As a minor style point, simplify JSON.parse(`"${json_text}"`) to JSON.parse(json_text).
#BaseZen's answer was very helpful for me to understand what was going wrong with my code. My JSON was incorrectly formatted even though online linters say its correct. Along with what BaseZen pointed out, JSON.parse() will not work with trailing commas. To fix this:
_remove_trailing_commas(json_string){
var regex = /\,(?!\s*?[\{\[\"\'\w])/g;
return json_string.replace(regex, '');
}
I found this information at SO post JSON Remove trailiing comma from last object
SO user Dima Parzhitsky's answer was what helped me also figure out this question.
This follows on from my question earlier about Visual Studio showing "" instead of ".
When I run the code below it creates a javascript array and returned as res[0] like below:
["Name","Name","Name"]
in visual studio it returns this:
"["Name","Name","Name"]"
When I run the code, this part shows the surrounding speech marks still (autocompletedata):
autocomplete(document.getElementById("rd-search-form-input"), autocompletedata );
This causes the code to not work. When i manually remove the surrounding double quotes, all works fine.
I've tried removing the start and end part of the string but it just removes the [ and ], which indicates that the string isn't surrounded by double quotes at all. I've also tried removing all double quotes but to no avail.
Can anyone explain whats going wrong?
var urlMethod = "/ajax.aspx/GetTeamMemberNamesList";
var params = new Object();
var result;
params.TeamID = 123;
result = SendAjaxSingleValue(urlMethod, params);
var res = result.d.split("|");
var autocompletedata = res[0];
autocompletedata.replace(/['"]+/g, '')
autocomplete(document.getElementById("rd-search-form-input"), autocompletedata );
To clarify the solution from the OP, the ajax call returns not the array itself but a JSON string, as is always the case when receiving data from a web server - hence why res[0] is returned as ["Name","Name","Name"].
Hence, in order to turn the response text into an actual array, it requires JSON.parse to perform the conversion.
Well, this was annoying - this fixed my issue:
autocomplete(document.getElementById("rd-search-form-input"), JSON.parse(autocompletedata));
[EDIT] I was modyfing the data later and it was reflected in the object when expanding it, I will accept my answer when I can.[/EDIT]
I've got a simple JSON string that needs parsing:
{"Points": [{"x": 0,"y": 33},{"x": 2200,"y": 28},{"x": 4400,"y": 23},{"x": 6600,"y": 20},{"x": 8800,"y": 19},{"x": 11000,"y": 18},{"x": 13200,"y": 17},{"x": 15400,"y": 15},{"x": 17600,"y": 13},{"x": 19800,"y": 12}]}
The string is generated by C++ code for graph drawing purposes. When I paste it into a json formatter it parses fine, giving proper values. The problem I'm facing are wierd Y values, for example the first object in array "Points" has y value of 20 - and there are no 20's anywhere in the string.
See attached picture, it explains everything. The code before what's on the picture is as follows:
RequestJSONParse: function(Data)
{
var Request = Data.split("|");
var RequestType = Request[0];
var RequestParams = Request[1];
var RequestData = undefined;
if (typeof Request[2] != "undefined" && Request[2] != "")
{
console.log("---");
console.log(Request[2]);
console.log("---");
RequestData = JSON.parse(Request[2]);
console.log("---");
console.log(RequestData);
console.log("---");
}
My question is - are the some special characters or a special way JSON.parse parses specifically x,y values? Or is this an encoding issue or something I can't even think of? I've been on this project for 2 years and didn't ever encounter anything like this and most of our UI is made by parsing JSON data.
Image explaining the problem
Check here your do like this
var json = "{\"Points\": [{\"x\": 0,\"y\": 33},{\"x\": 2200,\"y\": 28},{\"x\": 4400,\"y\": 23},{\"x\": 6600,\"y\": 20},{\"x\": 8800,\"y\": 19},{\"x\": 11000,\"y\": 18},{\"x\": 13200,\"y\": 17},{\"x\": 15400,\"y\": 15},{\"x\": 17600,\"y\": 13},{\"x\": 19800,\"y\": 12}]}";
var Request = json.split("|");
var data = JSON.parse(Request[0]);
console.log(data);
U can use above code if u r getting string in this way....
#JamesThorpe Was on point, I was modifying the object later and my changes were reflected in the object when it was expanded. The blue i symbol was the missing link for me.
I want to parse this content using Javascript. The data looks like this:
{"ss":[["Thu","7:00","Final",,"BAL","19","ATL","20",,,"56808",,"PRE4","2015"],["Thu","7:00","Final",,"NO","10","GB","38",,,"56809",,"PRE4","2015"]]}
Every single tutorial online teaches you how to parse JSON using Twitter, but I am not quite sure how parsing with JSON works.
I would like to set this up on a website to view the NFL team scores for a fun project and a good learning experience about parsing JSON, as I could care less about Twitter stuff.
Is this possible? Any good tutorials to start with? Even some starting code?
Generally speaking, you can use JSON.parse to do this. However, that snippet that you have does not appear to be strictly valid JSON (as seen here: http://jsfiddle.net/yK3Gf/ and also by validating the source JSON here: http://jsonlint.com/).
So you will either need to parse it by hand, or get nfl.com to fix up their JSON.
As an alternative, their JSON does parse successfully when using eval(), so you could parse it with something like:
var parsedData = eval('(' + jsonData + ')');
...as shown here: http://jsfiddle.net/yK3Gf/1/
Though be aware that parsing JSON in this way is generally frowned upon (particularly when the data being parsed is being delivered by a third-party source), as it leaves you open to XSS attacks should the data happen to include any executable code inside of it.
I am in a similar position - non javascript expert working on a fun project to familiarize myself with javascript, ajax, and json.
I took three different steps to handle the problem. I welcome any feedback on improving the solution.
The first step is to query the nfl site to pull down the scores. Because the source of the json, the nfl site, is different from your site, you will have to work around the javascript security constraints against cross domain querying. I found this stackoverflow link to be a good reference. I used JSONP for the workaround. I used http://whateverorigin.org/ as the indirection site.
$.getJSON('http://whateverorigin.org/get?url=' + encodeURIComponent('http://www.nfl.com/liveupdate/scorestrip/scorestrip.json') + '&callback=?', handleQueryForScoresResult);
As others have pointed out, the nfl site returns invalid json data. The following sample line illustrates the problem:
["Sun","4:25","Final",,"TEN","7","MIN","30",,,"55571",,"REG5","2012"],
Notice the empty array element values (the repeated commas with no data in between). So in my json callback function, I corrected the data by adding empty strings (two double quotes) to repeated commas before calling jquery to parse the json data:
function handleQueryForScoresResult(data) {
var jsonStr = data.contents;
jsonStr = jsonStr.replace(/,,/g, ',"",');
jsonStr = jsonStr.replace(/,,/g, ',"",');
var scoresData = jQuery.parseJSON(jsonStr).ss;
.
.
.
}
Lastly, I created GameScores object to encapsulate the json data.
function GameScore(scoreData) {
this.scoreData = scoreData;
scoreData[2] = scoreData[2].toLowerCase();
scoreData[5] = parseInt(scoreData[5]);
scoreData[7] = parseInt(scoreData[7]);
}
function GameScore_getAwayTeam() { return this.scoreData[4]; }
function GameScore_getHomeTeam() { return this.scoreData[6]; }
function GameScore_isFinal() { return this.scoreData[2]=="final"; }
function GameScore_getHomeTeamScore() { return this.scoreData[7]; }
function GameScore_getAwayTeamScore() { return this.scoreData[5]; }
function GameScore_doesHomeTeamLead() { return this.scoreData[7]> this.scoreData[5]; }
function GameScore_doesAwayTeamLead() { return this.scoreData[5]> this.scoreData[7]; }
function GameScore_getWeekId() { return this.scoreData[12]; }
GameScore.prototype.getHomeTeam = GameScore_getHomeTeam;
GameScore.prototype.getAwayTeam = GameScore_getAwayTeam;
GameScore.prototype.isFinal = GameScore_isFinal;
GameScore.prototype.getHomeTeamScore = GameScore_getHomeTeamScore;
GameScore.prototype.getAwayTeamScore = GameScore_getAwayTeamScore;
GameScore.prototype.doesHomeTeamLead = GameScore_doesHomeTeamLead;
GameScore.prototype.doesAwayTeamLead = GameScore_doesAwayTeamLead;
GameScore.prototype.getWeekId = GameScore_getWeekId;
I only added a few accessors as I did not need most of the data. Your needs may vary.
We are using mootools for stuff like that, but you can do it it plain JavaScript as well: http://www.json.org/js.html.
Let's assume you already have a valid JSON String (jsonString) to parse. (If you don't know how to retrieve a String to parse using XMLHttpRequest from the given url you will have to look into that first.)
With plain JavaScript you will have to add Douglas Crockford's JSON library (or something similar) in order to provide a parsing Function if there is no native implementation:
var json = json_parse(jsonString) ;
link
With a JavaScript library like jQuery this would be
var json = $.parseJSON(jsonString) ;
Now, traversing the resultant JSON Object is a whole other issue, because you will have to know its structure before you can retrieve specific data.
In this particular case -- if it was indeed well formed -- you would have to do the following:
var data = json.ss ;
for(var i = 0 ; i < data.length ; i++) {
var entry = data[i] ;
var day = entry[0] ; //!! the Arrays seem to have a format where the first entry always contains the data and so forth...
/* ... */
// then do something with the data bits
}
Your main problem is that fact that the JSON your pulling in is malformed or not valid according to RFC 4627.
What you can do is grab the copy the JSON data and format it using this tool http://www.freeformatter.com/json-formatter.html
After you have the formatted version then you can use the jQuery ajax call
$.ajax({
url: "your-formatted.json",
dataType: 'json',
success: function (data) {
for (var i = 0; i < data.ss.length; i++) {
document.write("Day: " + data.ss[i][0]);
document.write("<br/>");
document.write("Time: " + data.ss[i][1]);
document.write("<br/><br/>");
}
}
});
You shouldn't actually use document.write in your application. This is only for example purpose of displaying the data.
For this specific issue (the empty indexes within the arrays from the JSON response) I did a regex replacement with a lookahead assertion. Considering that request contains the XMLHttpRequest:
request.responseText.replace(/,(?=,)/gm, ",\"\"")
This will turn ,, into ,"", and will also work in case there are more commas in sequence, so ,,, becomes ,"","",. You can use JSON.parse() afterwards.
This malformed JSON can be parsed by the dirty-json NPM package (I am the author).
You can test a demo of the parser here: https://rmarcus.info/dirty-json
The parser interprets the JSON in your original question as equivalent to the following valid JSON:
{
"ss": [
[
"Thu",
"7:00",
"Final",
"BAL",
"19",
"ATL",
"20",
"56808",
"PRE4",
"2015"
],
[
"Thu",
"7:00",
"Final",
"NO",
"10",
"GB",
"38",
"56809",
"PRE4",
"2015"
]
]
}
How can I convert a string in javascript/jquery to a function?
I am trying to use a JSON parameter list to initialize a function. However, one of the parameters is a function, which I store as a string, and I get an error when I try to use eval() to return the function.
For example, if my JSON is:
json = { "one": 700, "two": "function(e){alert(e);}" }
Then in my code:
parameters = eval(json);
$('myDiv').addThisFeature({
parameter_1: json.one,
parameter_2: eval(json.two) // <= generates error
})
Example: http://jsfiddle.net/patrick_dw/vs83H/
var json = '{ "one": 700, "two": "function(e){alert(e);}" }';
var parameters = JSON.parse( json );
eval( 'var func = ' + parameters.two );
func( 'test' ); // alerts "test"
You'll need to load the JSON library in browsers that don't support it.
Or do two separate evals:
Example: http://jsfiddle.net/patrick_dw/vs83H/1/
var json = '{ "one": 700, "two": "function(e){alert(e);}" }';
eval( 'var parameters = ' + json );
eval( 'var func = ' + parameters.two );
func( 'test' );
I assume you're aware of the dangers of eval.
Looking for a way to not use eval this is the best I could come up with. Use the Function constructor to create a function from a string.
var parsed = JSON.parse('{"one":"700", "two":"function(){return 0;}" }');
var func = new Function('return ' + parsed.two)(); // return parsed.two function
alert(typeof func); // function
alert(func()) // 0
Use this:
parameters = eval('(' + json + ')');
$('#myDiv').addThisFeature({
parameter_1: parameters.one,
parameter_2: eval('(' + parameters.two + ')') // <= does not generate an error
});
Adding the parentheses at the beginning and end of the string prevents the syntax error.
Note, however, that you are parsing JSON using eval (which in some cases has security risks, but I assume that is irrelevant because you do want to run arbitrary code sent by the server). If you have the server-side flexibility (to send invalid JSON), you could just send the function not quoted as a string and eval should be able to parse that just fine.
See this SO question. As was said, JSON is meant to hold data. To treat a piece of the data as a function, you would first need to eval the string.
You are eval'ing an anonymous function, which of course won't be called by anything. If you really wanted to run the code in the json then the text would need to be alert(e).
However it doesn't sound like a very sensible thing to do. You'd be better off writing code to deal with the contents of the json object, rather than trying to run code embedded in the json.
Neither way is particularly nice, but if you can get rid of the function(e) wrapper bits, then you can use var myDynamicFunction = new Function("e", "alert(e);"); Otherwise, you're looking at using eval(). Eval() is evil in general. If this is JSON that you're getting back from a $.getJSON call or something, you're opening yourself up to security concerns.