Develop Reference

Variable in JSON Path - JavaScript

I already searched for similar issues but I didn't find anything that could help me yet.
I'm trying to reach a picture path (using JSON format) depending on the material type of the picked element. Actually, my code is built like this:
if (globalData.Material.Mat_type == "OSCILLOSCOPE") {
var picture = (globalData.Material.Oscilloscope.picture);
}
if (globalData.Material.Mat_type == "ALIMENTATION") {
var picture = (globalData.Material.Alim.picture);
}
But not optimized at all, so Im trying to make it this way :
var mat_type = (globalData.Material.Mat_type);
var picture = (globalData.Material[mat_type].picture);
But it doesn't work... Got some exception:
TypeError : globalData.Material[mat_type] is undefined.
I already tried a lot of things, have you got any idea? Thanks!

I outlined the issue with character case in the comment under the question, so presumably adjusting value of globalData.Material.Mat_type could do the trick:
var mat_type =
globalData.Material.Mat_type.charAt(0).toUpperCase() +
globalData.Material.Mat_type.substr(1).toLowerCase();
I can also see that this general rule may not be applicable in all cases. If it's not a typo, it won't work for the second case where Mat_type == "ALIMENTATION", because then you try to access Alim property of Material instead of Alimentation. In this case you could access property by prefix:
function pictureOf(material) {
if (!material || !String(material.Mat_type)) {
return null;
}
let mat_type = String(material.Mat_type).toUpperCase();
for (var propertyName in material) {
if (mat_type.startsWith(propertyName.toUpperCase())) {
return material[propertyName].picture || null;
}
}
return null;
}
console.log(pictureOf({
Mat_type: "OSCILLOSCOPE",
Oscilloscope: {
picture: "picture of oscilloscope"
}
}));
console.log(pictureOf({
Mat_type: "ALIMENTATION",
Alim: {
picture: "picture of alimentation"
}
}));
But this kind of approach can be error prone, if multiple properties share the same prefix. There's also a hidden issue with case-insensitive prefix matching in case you use some special unicode characters in property names. Lastly this method is not efficient, because it has to iterate over all properties of the object (worst case scenario). It can be replaced with much safer property mapping:
const matTypeMapping = {
"ALIMENTATION": "Alim"
};
function pictureOf(material) {
if (!material || !String(material.Mat_type)) {
return null;
}
let matType = String(material.Mat_type);
// find property mapping or apply general rule, if mapping not defined
let propertyName = matTypeMapping[matType] ||
matType.charAt(0).toUpperCase() + matType.substr(1).toLowerCase();
return material[propertyName].picture || null;
}
console.log(pictureOf({
Mat_type: "OSCILLOSCOPE",
Oscilloscope: {
picture: "picture of oscilloscope"
}
}));
console.log(pictureOf({
Mat_type: "ALIMENTATION",
Alim: {
picture: "picture of alimentation"
}
}));
NB: To avoid headaches, maybe you should prefer strict equality operator over loose equality operator.

Problem Solved
Peter Wolf was right ! It was a case-sensitive issue
I actually don't know how to promote his comment, sorry for this..
Anyway, thank you guys !

var mat_type = (globalData.Material.Mat_type);
if(mat_type!==undefined)
var picture = (globalData.Material[mat_type].picture)
Just do an existential check before accessing the value, for keys that may not be present.

Changing the JSON key and keeping its index same

I want to change the key of JSON attribute and keep/persist its position/Index.
E.g.
{"Test1" : {
mytest1:34,
mytest2:56,
mytest6:58,
mytest5:89,
}
}
Now I want to change the key mytest6 to mytest4 and keep its position as it is.
Note: In my case I can't use Array.
Thanks.

jsonObj = {"Test1" : {
mytest1:34,
mytest2:56,
mytest6:58,
mytest5:89,
}
};
var old_key = "mytest6";
var new_key = "mytest4";
if (old_key !== new_key) {
Object.defineProperty(jsonObj.Test1, new_key,
Object.getOwnPropertyDescriptor(jsonObj.Test1, old_key));
delete jsonObj.Test1[old_key];
}
console.log(jsonObj);
This method ensures that the renamed property behaves identically to the original one.
Also, it seems to me that the possibility to wrap this into a function/method and put it into Object.prototype is irrelevant regarding your question.
Fiddle

Get path of element in object without looping through all elements (second hierachy level unkown)

I have the following object:
var oBadge = {
COMMENT_CREATED: {
FIRST_COMMENT_CREATED: {
code: "FIRST_COMMENT_CREATED",
src: "",
name: "Socializer",
text: "Create a comment for an idea",
condition: {
today: null,
over_all: 1
}
}
}
};
i need to check if a string i get (for example "FIRST_COMMENT_CREATED") is contained in the oBadge model. The object contains more elements - not only the comment_created element. Therefore i cannot define to check it there.
I found the following function to determine wether the element is contained within the object or not, but I also need the contained data, not only the statement whether it is contained or not.
oBadge.hasOwnProperty("FIRST_COMMENT_CREATED")
What i'm basically looking for is a way to skip the second hierachy level on my check - like:
if(oBadge.[<all>]["FIRST_COMMENT_CREATED"] !== undefined) {
// return data
}

There is no way to skip the hierarchy without looping through the object, you should use the for...in loop:
for (var prop in oBadge) {
if(oBadge[prop].hasOwnProperty("FIRST_COMMENT_CREATED")) {
// return data
}
}

Use a function and a loop (for-in):
function find(key, obj){
if(!obj.hasOwnProperty) return false; // no primitive data please!
if(obj.hasOwnProperty(key))
return obj[key];
else return false;
}
for(var key in oBadge){
if(find("FIRST_COMMENT_CREATED", key))
// code
}

jQuery see if key existing in entire JSON

I've got some JSON data in which I'm trying to check if a key is contained in the entire array and add a class or do something else. If there is one key contained in the array I want to perform an action otherwise if there is no key do something. I've been banging my head for hours ,inArray doesn't seem to be working for me or hasOwnProperty. I've got to be doing something stupid simple wrong here. Kind of a newb so please include code samples were applicable.
JS Fiddle: http://jsfiddle.net/AtC4G/
var data={"users":[
{
"firstName":"Ray",
"lastName":"Villalobos",
"userName":"rvilla",
"joined": {
"month":"January",
"day":12,
"year":2012
}
},
{
"firstName":"John",
"lastName":"Jones",
"joined": {
"month":"April",
"day":28,
"year":2010
}
},
{
"firstName":"John",
"lastName":"Johnson",
"userName": "jjoe"
}
]}
if($.inArray('userName', data.users) == -1) { alert('not in array'); }
if(data.users.hasOwnProperty('userName')){
alert('do something');
}

The [ indicates an array, so you need to treat it as an array (data.users[0], not just data.users):
if($.inArray('userName', data.users[0]) == -1) { alert('not in array'); }
if(data.users[0].hasOwnProperty('userName')){
alert('do something');
}

you can compare a variable with a undefined value
for(user_index in data.users){
user=data['users'][user_index];
if(user.userName==undefined){
alert('username undefined in user '+user.firstName+' '+user.lastName);
}
}

To find out, whether a property is set, I would go for a native JS.solution:
function containsKey(key){ return function(el){
return el[key]!==undefined;
}};
containsUserName=containsKey("userName");
console.log(data.users.some(containsUserName))
This is all you need.
containsKey is a closure, which saves the key, for which you are looking for.
containsUsername is the function, which is used to look for a specific property.
Read the MDN documentation of Array.some() for compatibility etc.
Here is a Fiddle to play with.
If you want to extract that element: Array.filter() might be of interest.

Script debugger confirms intended conditional check between JSON key and string, however I am getting an undesired result?

I am looking to modify the output table I am getting from this handy Json-to-HTML-Table script I stumbled upon here on SO. There is a point (line 86) where json-to-table.js passes a JSON object and generates array keys to be used as table headers. Optionally, this array_key function can generate only one key for a specified search_value parameter passed. I however [attempted] to modify it so that ALL array keys that did NOT match the search_value would be returned. Here is the function after my changes:
function array_keys(input, search_value, argStrict)
{
var search = typeof search_value !== 'undefined', tmp_arr = [], strict = !!argStrict, include = '', key = '';
if (input && typeof input === 'object' && input.change_key_case) { // Duck-type check for our own array()-created PHPJS_Array
return input.keys(search_value, argStrict);
}
for (key in input)
{
if (input.hasOwnProperty(key))
{
include = false;
if (search)
{
if (strict && input[key] == search_value)
include = false;
else if (input[key] == search_value)
include = false;
else
include = true;
}
if (include)
tmp_arr[tmp_arr.length] = key;
}
}
return tmp_arr;
}
Now, the reason I did this is because I want my generated table to not include a specific column from my JSON object:
{
"examItemCategories": [
{
"catgoryName": "01-Normal processes",
"catgoryPath": "General Area\\01-Normal processes",
"numberOfItems": 2,
"percentage": "6.06"
}
]
}
Given that I can not modify the original JSON obj passed, I was determining whether or not to attempt to modify the table post creation (e.g. remove column), or during. After looking at the array_keys function, I felt I could easily invert the conditional checking for the search_value.
I now call array_keys(parsedJson[0], 'catgoryPath'); from json-to-table script. (Yes, catgoryPath is the correctly spelled name haha). Then I set a break point at the for loop within array_keys function to follow it through in Firebug.
First iteration: catgoryName is added to tmp_arr, 2nd iteration: catgoryPath is added to tmp_arr...and continues through 3rd and 4th iterations. I do not wantcatgoryPath added.
Looking at script debugger, on the 2nd iteration, whether or not catgoryPath gets added comes down to the conditional: else if (input[key] == search_value) line. The thing is, on the respective iteration both key and search_value variables equal "catgoryPath" according to Firebug. So therefore, include = false; should fire correct?
Any help is appreciated, apologies for the length and liberal usage of inline code.

Instead of using the array_keys function from the json-to-table script, if you are using JS > 1.8.5 you can use Object.keys(obj) to return an array of a given object's own enumerable properties.
The returned array of keys are then used as table headers under which the table populates with JSON data thanks to the script. Prior to the creation of table, I took my array of table headers and used array.splice(index, howMany) instead of delete (see here) to preserve my array index values.