I use basic array to make reference to icons like this:
{name: "text", avatar: srcs[15]}
This works great, but now I dynamically create an array from my json api and it gives me array of objects like this:
{name: "text", avatar: "srcs[15]"}
so I cannot reference to my avatars now. How can I remove double quotes to get my array work again?
Please note that I don't want to get the srcs[15] value to the array, just make a reference to the source array.
The JSON data format does not support references. What you want it not possible.
You need to either:
Put the data you want there explicitly (this may involve duplication) or
Describe the relationship in a way that the program consuming the JSON can interpret as a reference. You could use the reviver argument of JSON.parse to inflate the description back to the data you want to point it to.
JSON is self-contained static data, and it can't reference named variables or objects outside of its own structure.
You can do it like this instead:
{ "name": "text", "avatarIndex": 15 }
And then do one of these to use it:
var avatar = srcs[data.avatarIndex]; // Avatar object in separate variable
// or
data.avatar = srcs[data.avatarIndex]; // Avatar object added into data
You should just put either the value or the whole array , you have also to read about what format json support here
Here's my suggested solutions
var array = [1, 2, 3, 4, 5, 6]
var json1 = {
name: 'test',
value: array
}
console.log("solution 1 :" + json1.value[2])
var json2 = {
name: 'test',
value: array[2]
}
console.log("solution 2 :" + json2.value)
Related
I have an array called values. At present, I'm appending new data to this array as such:
values.push(guests);
The result of my array is something like this:
["123456789", "Joe", "Bloggs", "Test Corp", "fiji", true, "guest, guest 2, guest 3", true]
I have now realised that in its present state this data is useless to me as I cannot tell what each element is. In my example above, the first long number is an account number and the second element is a first name but these are liable to change. E.g the company name Test Corp may not always exist in the data. This means I cannot use the numerical key [3] to target it because it may not be present.
Therefore I need to code this data into something that I can assign both a label for the data, and the data value. I'm guessing the best way to do this would be with an JSON object.
How can I create a key->value pair object? I would need to replace my .push() code above to instead add the value of COMPANY NAME -> Test Corp so that it can be deciphered later.
For reference, I am then stringifying this data and using an AJAX request to POST it to a PHP script where it will need to be arranged into variables e.g $company_name = 'Test Corp';
You're talking about a plain JavaScript object. JSON is a transfer format inspired by JavaScript syntax.
To make an object, just initialize a variable:
var values = {};
And add properties:
values.accountNumber = "123456789";
values.firstName = "Joe";
etc. If you know the properties up front and have values available, you can make the object in one step:
var values = {
accountNumber: "12345678",
firstName: "Joe",
// ...
};
I have an object ( array of hashes ) and I need to convert it into ordered key value pairs.
This is object:
var places_info = [
{"place_id":180,"name":"Abc","city":"Gotham"},
{"place_id":161,"name":"Def","city":"Sin City"},
{"place_id":178,"name":"Ghi","city":"Timbuktu"},
{"place_id":179,"name":"Jkl","city":"Acapulco"},
{"place_id":174,"name":"Mno","city":"Desire"}
];
And I need function to return key/value (place_id/name) pairs in same (alphabetical by name) order:
{
'180': 'Abc',
'161': 'Def',
'178': 'Ghi',
'179': 'Jkl',
'174': 'Mno'
}
Actual use: I need it as input for Jeditable Select-input (actual example on demo page). Select-type needs for data-property key/value pairs or function which returns them. So far I got select options in random order, but--as you may imagine--I need them ordered by value....
As for Jeditable the data may be just a fake hash (string formed as JSON key/value pairs), my only solution is like this:
var arr = new Array;
for ( i in places_info ) {
arr.push( "'" + places_info[i].place_id + "':'" + places_info[i].name + "'" );
}
var uglyString = '{' + arr.join(',') + '}';
Is there some more elegant and intuitive approach for such goal? I'd like to keep my data in proper data structure. Converting it to flat string seems like hack.
Edit
I must reconsider the problem. I did not test Jeditable with generated string and seems it evals string into hash and then my desired order is gone. So, this problem needs different approach. Maybe I need make my own datatype for Jeditable. But this seems like different question.
Until ES6, there is NO guaranteed order for properties on a Javascript object. They are unordered. If you need order and need to support environments before ES6, then you can't just use properties on an object and get a guaranteed order of those properties.
So your choice is to pick some other data structure that can reliably express order. Collapsing it all down to a string like you've done is one choice, though that means it has to be re-parsed in order to be useful to Javascript. It would be better to keep it in some natively accessible Javascript format. For order, that means using an array.
You can return ordered pairs by returning an array for the ordering and then there are several choices for what to put in the array. Here are several examples of ordered key/value pairs:
// array of objects
var a = [{key: "greeting", value: "hello"}, {key: "salutation", value: "welcome"}];
Since that seems a little verbose to me, I often use a shortcut that just knows that every other element is a key, then value, then key, then value and doesn't have to spell out those property names over and over:
// alternating key/value
var a = ["greeting", "hello", "salutation", "welcome"];
Or, you could put each ordered pair in an array itself so each sub-array is an ordered pair:
// sub-arrays
var a = [["greeting", "hello"], ["salutation", "welcome"]];
The properties order in objects are not guaranted in JavaScript, you need to use an Array.
Take a look at this:
var obj = {
'180': 'Abc',
'161': 'Def',
'178': 'Ghi',
'179': 'Jkl',
'174': 'Mno'
};
for (var i in obj) { console.log(i); };
will give you:
161, 174, 178, 179, 180
Just use JavaScript's native Map data structure. It preserves order. We are now way past 2015 so it should be standard in almost any runtime.
e.g.
const m = new Map([["greeting", "hello"], ["salutation", "welcome"]])
See Also https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map
For a web site I'm creating, I have to create a quote based on data provided as a JSON string from the server. I've been looking through this site (and various others) but still am unsure on the best way to query/search the data.
For example, I need to get the Area Name from the Area ID. I need to get the maximum age for an area and also the price for a given minimum/maximum age.
I also want to get an array of prices.
Is it best to create a Javascript object from the string using the eval method? Or should I be using jQuery.
Thanks for your help.
({"SkiPass":[{"Id":1,"Area":"Chamonix","Rates":[{"Id":1,"AgeMin":0,"AgeMax":2,"Price":2.5},{"Id":2,"AgeMin":3,"AgeMax":17,"Price":5.0},{"Id":3,"AgeMin":18,"AgeMax":30,"Price":6.2},{"Id":4,"AgeMin":31,"AgeMax":59,"Price":7.4}]},
{"Id":2,"Area":"Megeve","Rates":[{"Id":1,"AgeMin":0,"AgeMax":2,"Price":1},{"Id":2,"AgeMin":3,"AgeMax":17,"Price":2.0},{"Id":3,"AgeMin":18,"AgeMax":30,"Price":2.2},{"Id":4,"AgeMin":31,"AgeMax":59,"Price":4.4}]},
{"Id":3,"Area":"Verbier","Rates":[{"Id":1,"AgeMin":0,"AgeMax":2,"Price":1.5},{"Id":2,"AgeMin":3,"AgeMax":17,"Price":3.0},{"Id":3,"AgeMin":18,"AgeMax":30,"Price":4.2},{"Id":4,"AgeMin":31,"AgeMax":59,"Price":5.4}]}]})
Create a JavaScript object from the string, most definitely, but do it with legitimate JSON parsing facilities and not "eval()". You could use jQuery, but there are other solutions, such as the JSON tools available from json.org, which are small and simple.
Once it's a JavaScript object, well then your needs should guide you as to whether some query solution is necessary, or instead that it's just a simple matter of programming.
I think the best method is jLinq: http://hugoware.net/Projects/jLinq it's like doing a SQL query on JSON.
It doesn't needs jQuery.
I use it, and it's great.
Create the object from the JSON string using JSON.parse() or jQuery.parseJSON() if you are already using jQuery -- or just pass it as from the server side as JSON.
You can then iterate through the object to find the record you want. Or, you can use build your objects so that you can naturally grab data from them.
FloatLeft - as Dan points out, your task would be much easier if you could use XPath but there is no need to re-write your data in XML format. With DefiantJS (http://defiantjs.com) you can now query JSON structure with XPath expressions.
DefiantJS extends the global object JSON with the method "search", which enables XPath queries and returns an array with the matches (empty array if no matches were found). The returned array is equipped with aggregate functions as well; one of these "sortDesc".
Check out this working fiddle;
http://jsfiddle.net/hbi99/H3PR3/
var data = {
"SkiPass": [
...
{
"Id": 3,
"Area": "Verbier",
"Rates": [
{ "Id": 1, "AgeMin": 0, "AgeMax": 2, "Price": 1.5 },
{ "Id": 2, "AgeMin": 3, "AgeMax": 17, "Price": 3 },
{ "Id": 3, "AgeMin": 18, "AgeMax": 30, "Price": 4.2 },
{ "Id": 4, "AgeMin": 31, "AgeMax": 59, "Price": 5.4 }
]
}
]
},
res1 = JSON.search( data, '//SkiPass[Id=3]/Area' ),
res2 = JSON.search( data, '//*[Area and Id=3]/Rates' )
.sortDesc('AgeMax'); // <-- sorting descending by the value of "AgeMax"
document.getElementById('name').innerHTML = res1;
document.getElementById('max_age').innerHTML = res2[0].AgeMax;
document.getElementById('price').innerHTML = res2[0].Price;
I have a very simple array (please focus on the object with "points.bean.pointsBase" as key):
var mydata =
{"list":
[
{"points.bean.pointsBase":
[
{"time": 2000, "caption":"caption text", duration: 5000},
{"time": 6000, "caption":"caption text", duration: 3000}
]
}
]
};
// Usually we make smth like this to get the value:
var smth = mydata.list[0].points.bean.pointsBase[0].time;
alert(smth); // should display 2000
But, unfortunately, it displays nothing. When I change "points.bean.pointsBase" to something without dots in its name - everything works.
However, I can't change this name to anything else without dots, but I need to get a value? Is there any options to get it?
What you want is:
var smth = mydata.list[0]["points.bean.pointsBase"][0].time;
In JavaScript, any field you can access using the . operator, you can access using [] with a string version of the field name.
in javascript, object properties can be accessed with . operator or with associative array indexing using []. ie. object.property is equivalent to object["property"]
this should do the trick
var smth = mydata.list[0]["points.bean.pointsBase"][0].time;
Try ["points.bean.pointsBase"]
If json object key/name contains dot......! like
var myJson = {"my.name":"vikas","my.age":27}
Than you can access like
myJson["my.name"]
myJson["my.age"]
I can only send string or numeric values,how to send an array?
You'll probably get a slew of answers all saying "JSON".
Here are some case specific examples. 'data' holds what you send.
var numArray = [17, 42, 23];
data = '[' + numArray + ']';
var strArray = ['foo', 'bar', 'baz'];
data = '["' + numArray.join('", "') + '"]';
For the general case, use a function that recursively encodes objects to JSON. If you really want me to, I'll post an example implementation, but it's a fun project so you might want to give it a try. If you're using a Javascript library, it might have a JSON encoder of it's own (such as jQuery's serializeArray).
There's are no built-in JSON serializers in javascript so you will need to use a library. A good one is json2.js.
Here's a sample:
// suppose you have an array of some objects:
var array = [{ prop1: 'value1', prop2: 10 }, { prop1: 'value2', prop2: 20 }];
// convert it to json string:
var jsonString = JSON.stringify(array);
// TODO: send the jsonString variable as a parameter in an ajax request
// On the server side you will need a JSON deserializer
// to convert values back to an array of objects
I can only send string or numeric values
Actually you can only send strings. When you include a number it is just turned into a string; it's up to the server-side script to parse that back into a number if it wants to.
how to send an array?
The native HTML-forms way of sending multiple values is using multiple inputs. You can reproduce this by including the same named parameter multiple times. To send [1,2,3]:
http://www.example.com/ajax.script?a=1&a=2&a=3
The same multiple-parameter-instance query string can be sent in an AJAX post request.
If you are using a higher-level framework to create the form-encoded string, it depends on the framework how it accepts multiple parameter instances. For example with jQuery you can post an object like {a: [1,2,3]}.
The other way is to forget the standard HTML form encoding and just pass all your values in whatever special encoding you like that allows you to retain datatypes and structure. Usually this would be JavaScript value literals (JSON):
http://www.example.com/ajax.script?a=%5B1%2C2%2C3%D
(that is, [1,2,3], URL-encoded.) You then need a JSON parser on the server to recreate native array values there.
You can actually send Arrays in a much cleaner way instead of trying to encoding JSON.
For example, this works
$.post("yourapp.php", { 'data[]': ["iphone", "galaxy"] });
See http://api.jquery.com/jQuery.post/ for more.