Develop Reference

How to display simple DIS PDU from JSON file in Tabulator

I have a sample DIS PDU that has been stored in a JSON file. I want to be able to read that file, and then display it using Tabulator on a web page. I am having problems with the "PDUHeader" and the "EntityID" section labels. The JSON parser in Tabulator is giving errors on these lines.
{
"PDUHeader": {
"ProtocolVersion": 1,
"ExerciseID": 123,
"PDUType": 1,
"ProtocolFamily": 1,
"Timestamp": 123,
"Length": 23,
"PDUStatus": 45
},
"EntityID": {
"SiteNumber": 6,
"ApplicationNumber": 1,
"EntityNumber": 1
}
}
Tried combining the Tabulator example where you download local JSON file, and the "Column Groups" example as listed here:
Tabulator Examples Page

How to model the rows in getData() since i have nested JSON data?

I want to display these fields :name, age, addresses_id, addresses_city, addresses_primary for each person into data studio.
My JSON data
{
"data": [
{
"name": "Lio",
"age": 30,
"addresses": [
{
"id": 7834,
"city": "ML",
"primary": 1
},
{
"id": 5034,
"city": "MM",
"primary": 1
}
]
},
{
"name": "Kali",
"age": 41,
"addresses": [
{
"id": 3334,
"city": "WK",
"primary": 1
},
{
"id": 1730,
"city": "DC",
"primary": 1
}
]
},
...
]
}
there is no problem if i don't render the addresses field
return {
schema: requestedFields.build(),
rows: rows
};
//rows:
/*
"rows": [
{
"values": ["Lio", 30]
},
{
"values": ["Kali", 41]
},
...
]
*/
The problem is
I'm not able to model the nested JSON data in Google Data Studio. I
have the problem exactly in the "addresses" field.
Could anyone tell me what format should be for the rows in this case?

As you already know, for each name of your dataset, you clearly have more than one row (one person has multiple addresses). Data Studio only accepts a single data for each field, since arrays are not supported at all. So you need to work on this.
There are some ways to solve this, but always keep in mind that:
getSchema() should return all available fields for your connector (the order doesn't really matter, since Data Studio always sort alphabetically the available fields)
getData() should return a list of values. But here the order is relevant: it should be the same as the parameter passed to getData() (which means the results should be dynamic, sometimes you'll return all values, sometimes not, and the order may change).
Solution 1: Return multiple rows per record
Since you can produce multiple rows for each name, just do it.
To achieve this, your field definition (=getSchema()) should include fields address_id, address_city and address_primary (you can also add address_order if you need to know the position of the address in the list).
Supposing getData() is called with all fields in the same order they were discribed, rows array should look like this:
"rows": [
{
"values": ["Lio", 30, "7834", "ML", 1]
},
{
"values": ["Lio", 30, "5034", "MM", 1]
},
{
"values": ["Kali", 41, "3334", "WK", 1]
},
{
"values": ["Kali", 41, "1730", "DC", 1]
},
...
]
IMO, this is the best solution for your data.
Solution 2: Return one address only, ignoring others
If you prefer one row per person, you can get one of the addresses and display only it (usually the main/primary address, or the first one).
To achieve this, your field definition (=getSchema()) should include fields address_id, address_city and address_primary.
Supposing getData() is called with all fields in the same order they were discribed, rows array should look like this:
"rows": [
{
"values": ["Lio", 30, "7834", "ML", 1]
},
{
"values": ["Kali", 41, "3334", "WK", 1]
},
...
]
Solution 3: Return all addresses, serialized in a field
This is helpful if you really need all information but do not want a complex scheme.
Just create a field called addresses in your field definition (=getSchema()) and write the JSON there as a string (or any other format you want).
Supposing getData() is called with all fields in the same order they were discribed, rows array should look like this:
"rows": [
{
"values": ["Lio", 30, "[{\"id\": 7834, \"city\": "ML", \"primary\": 1}, {\"id\": 5034, \"city\": \"MM\", \"primary\": 1}]"]
},
{
"values": ["Kali", 41, "[{\"id\": 3334, \"city\": \"WK\", \"primary\": 1}, {\"id\": 1730, \"city\": \"DC\", \"primary\": 1}]"]
},
...
]
This solution may appear senseless, but it is possible to interact with this data later in DataStudio using REGEX if really needed.
Solution 4: Create a different field for each address
If you're sure all records has a maximum number of addresses (in you example, both names have 2 addresses, for example), you can create multiple fields.
Your field definition (=getSchema()) should include fields address_id1, address_city1, address_primary1, address_id2, ... address_primaryN.
I wouldn't explain how rows should look like in this situation, but it is not hard to guess with the other examples.

How to search and select an object in JSON

Consider a JSON like this:
[{
"type": "person",
"name": "Mike",
"age": "29"
},
{
"type": "person",
"name": "Afshin",
"age": "21"
},
{
"type": "something_else",
"where": "NY"
}]
I want to search in the JSON value with a key (for example type='person') and then select a whole object of matched item in JSON. For example when I search for type='person' I expect this value:
[{
"type": "person",
"name": "Mike",
"age": "29"
},
{
"type": "person",
"name": "Afshin",
"age": "21"
}]
Because it's a really big JSON value, I don't want to do a brute-force search in all nodes, so I think the only way is using Regular Expressions but I don't know how can I write a Regex to match something like above.
I'm using NodeJs for the application.

Using underscore.js#where:
var results = _(yourObject).where({ type: 'person' })
If your data set is very very big [e.g. 10k or so], consider filtering / paginating stuff server side.

Plain javascript :
var results = dataset.filter(function(p) {
if(p.type == 'person')
return true;
});

If the requirement is to scan multiple times through the collection, the following one time construction overhead might be of worth.
Use hashing based on values of type.Convert the current data structure to hash map.
var hashMap ={
};
hashMap['person'] =[{},{}];
Hope this helps you.

Use
$.grep(jsonarrayobj,function(n, i){
if(n.type==="person")
{}
})

Parsing JSON with jQuery, retrieving two variables.

I have a online JSON file that looks something like this:
[
{
"j": 0,
"i": 0,
"DepartureTime": "\/Date(1331667480000+0100)\/",
"ArrivalTime": "\/Date(1331668860000+0100)\/",
"Remarks": [],
"TravelStages": [
{
"ID": 0,
"DepartureStop": {
"WalkingDistance": 0,
"ArrivalTime": null,
"AlightingAllowed": false,
"DepartureTime": null,
"BoardingAllowed": false,
"RealTimeStop": true,
"Rank": 0,
"Lines": null,
"StopPoints": [
{
"ID": 1,
"Name": "1",
"X": 608127,
"Y": 6645778
}
],
"Zone": "1",
"X": 608133,
"Y": 6645768,
"ID": 2300500,
"Name": "Visperud (i Solheimvn)",
"District": "Lørenskog",
"Type": 0,
"Stops": [],
"ShortName": "VIS"
}]
What I want is the grab out the DepartureTime and ArrivalTime, I've seen some examples on how to parse the flickr JSON. But I can't figure out how I can parse this. I also want to store the departureTime and arrivalTime in two separate variables since the content of this two is a time measured in milliseconds since 1970. Can somebody give me a hint on how a can do this, am totally new to Javascript/JSON

Do you have jQuery in your project? If so, you can easily parse the JSON string like this
var obj = $.parseJSON(theJsonText);
alert(obj.DepartureTime);
If not, I suggest including the JSON library (link) and using that.

You can try something like this, assuming that your json file is in jsonfile.json
$.getJSON('jsonfile.json', function(data){
alert("Departure Time: "+ data.DepartureTime);
alert("Arrival Time: "+ data.ArrivalTime);
});
http://api.jquery.com/jQuery.getJSON/

$.getJSON('http://your.domain.example/path/to/file.json', function(data) {
departure_time=data.DepartureTime;
arrival_time=data.ArrivalTime;
do_something_with(departure_time,arrival_time);
});
then do_something_with(str,str) would be called with the strings "\/Date(1331667480000+0100)\/" and "\/Date(1331668860000+0100)\/" (in your example).
you'll still have to convert the dates to numbers, e.g. by running:
parsed_date=new Date(parseInt(input_string.substr(7)));
//substr(7) cuts after "\/Date(", and parseInt ignores ")\/"
//but I don't know how it handles "+0100"

Thats an array containing objects, so you should be able to just set some vars equal to the properties of the first index. to use it like an object, it needs to be parsed.. so either eval(thatJson) or $.parseJSON(thatJson) and then iterate through it.
var responses = [
{
"j": 0,
"i": 0,
"DepartureTime": "\/Date(1331667480000+0100)\/",
"ArrivalTime": "\/Date(1331668860000+0100)\/",
"Remarks": [],
...
}];
var dep = responses[0].DepartureTime;
var arr = responses[0].ArrivalTime;

According to JSONLint.com, your string isn't valid JSON. That is, however, a different issue than what your question asks for.
Assuming a valid subset of your string
var a = '[{"j": 0,"i": 0,"DepartureTime": "/Date(1331667480000+0100)/", "ArrivalTime": "/Date(1331668860000+0100)/","Remarks": []}]';
var obj = $.parseJSON(a);
console.log(obj[0].ArrivalTime);​

Fetch JSON data from a file

I got a very simple txt file in JSON format:
{
"menu": "File1",
"bday": [
{
"name": "teo",
"date":"22"
},
{
"name": "john",
"date": "9"
},
{
"name": "maria",
"date": "15"
}
]
}
All I want is to just fetch the data and print them. Like:
teo : 22
john:9
...etc...
I don't care about this. I just want to fetch the data.

Your answer is plainly XMLHttpRequest, which is multi-browser compatible JavaScript without need for a library. You can always create your own library for some backward-compatibility.

Put the JSON in a file on your server (for example, data.js) and then use jQuery to fetch the file. Something like this:
var json;
$.getJSON("data.js", function(data){
json = data;
});