CODEWITHSUNDEEP
javascriptjsondate
Rajagopal 웃
Rajagopal 웃

Reputation: 8471

defining date in json file

I wonder to know how to set today's date in json file like we are using in js.

Is there any option to specify Date.today() in json file?

Because, json data has date object which specifies system date whenever we read the json file.

Hope, you will understand what i am trying to say.

Thanks in advance,

-Raja.

Upvotes: 14

Views: 98458

Answers (9)

Yashpreet Bathla
Yashpreet Bathla

Reputation: 1

Inspired from Joseph answer, i thought to replace timestamp using regex with my date function that you want to put.

function getDateBeforeDays(days) {
    const currentDate = new Date();
    currentDate.setDate(currentDate.getDate() - days);
    return currentDate;
}

function replaceTimestampWithMockDate(jsonString, days) {
    try {
        const timeRegex = /\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?([+-]\d{2}:\d{2})?/g;

        // Replace all occurrences of the time format with getDateBeforeDays
        const updatedJsonString = JSON.stringify(jsonString).replace(timeRegex, () =>
            getDateBeforeDays(days ?? 40),
        );

        return JSON.parse(updatedJsonString ?? {});
    } catch (error) {
        return jsonString; // Return the original string if there's an error
    }
}

const jsonString = '{"timestamp": "2023-07-25T05:01:18.868+00:00", "value": 42}';
const mockDays = 30; // Replace with the number of days for the mock date

const sanitizedData = replaceTimestampWithMockDate(jsonString, mockDays);

Upvotes: 0

Fai Ng
Fai Ng

Reputation: 800

I use Gson in java to create json output, but Gson does not allow me to put javascript functions into the json. So this is what I do: Use replacement tags for the places you want to put code(like one of the earlier answers). Then get the text of the json, replace the tags, and then save the text to your json file:

    Map<String, String> dynamicDates = new HashMap<>();
    dynamicDates.put("d1", "new Date()");
    dynamicDates.put("d2", "new Date(2015, 0, 1, 9, 30)");
    dynamicDates.put("d3", "new Date(2015, 0, 1, 12, 30)");

    JsonObject json = new JsonObject();
    JsonObject root = new JsonObject();
    JsonObject level_1_A = new JsonObject();
    JsonObject level_1_B = new JsonObject();
    json.add("root", root);
    root.add("level_1_A", level_1_A);
    root.add("level_1_B", level_1_B);

    level_1_A.addProperty("d1", "${d1}");
    level_1_A.addProperty("d2", "${d2}");
    level_1_B.addProperty("d3", "${d3}");

    StringBuilder sb = new StringBuilder();
    new GsonBuilder().setPrettyPrinting().create().toJson(json, sb);

    String str = sb.toString();
    for (String key : dynamicDates.keySet()) {
        str = str.replace("\"${" + key + "}\"", dynamicDates.get(key));
    }
    String jsonText = str;
    String javascriptText = "var myJson = " + str + ";";

    System.out.println(jsonText);
    System.out.println(javascriptText);

So there is nothing left to be done on the consumption side in using this json. And the first output is:

    {
      "root": {
        "level_1_A": {
          "d1": new Date(),
          "d2": new Date(2015, 0, 1, 9, 30)
        },
        "level_1_B": {
          "d3": new Date(2015, 0, 1, 12, 30)
        }
      }
    }

My use of json is usually saving it as javascript with an assignment, so this has been working for me.

Upvotes: 1

Joseph
Joseph

Reputation: 119867

JSON is a structured transport format. It does not have logic in it.

But here are options:

  1. Why not just get the date when you read the file instead?

  2. Have a server generate that JSON that includes the date at which it was generated. However, this is not ideal if you want the current date. By the time you read the file, the date generated by the server is already past.

  3. build a parser that parses a string and make it search for custom markup.

For example, special markup is contained in @{}. Get the command inside, determine the command, and execute replacement.

var jsonString = '{"data1" : "foo","date" : "@{currentdate}"}'

In this case, I'll find @{currentdate}. I should create a function corresponding to this command to replace @{currentdate} into the current date during read (in the format you want)

var parsedString = jsonString.replace(/@\{(\w+)\}/g, function(match, group) {    
    if (group === 'currentdate') {
        return new Date();
    } 
    else if (group === 'anotherCommand') {
        return 'anotherValue';
    } //and so on
});

and the result is like this:

jsonString = '{"data1" : "foo","date" : "Fri May 04 2012 01:17:07 GMT-0700 (PDT)"}'

Upvotes: 12

Tito
Tito

Reputation: 9054

it will be good to collect all the dates you want to transfer into a 

Collection<String> dates = new ArrayList<String>();

Convert this collection to a json object and then at the receving end,convert it back to date. You can use joda date time API for conversions.

Upvotes: 0

Sean Mickey
Sean Mickey

Reputation: 7716

I suggest that you consider using the JSON-js (json2.js) parser, because it parses all standard JSON, but also allows you to add custom parse handling logic, called a reviver function, which fits your scenario very well. The basic syntax to invoke the JSON parser with a custom handler looks like this:

var myObject = JSON.parse(myJSONtext, reviverFunction);

Using your example input as a guide, it could be set up to work like this:

var jsonTxt = '[{' +
        '"data1": "foo",' +
        '"Date":  "",' +
        '"childs": [{' +
            '"data2": "stack",' +
            '"Date": ""' +
        '}{}{}...]}]';    //and-on-and-on as in your comment

myData = JSON.parse(jsonTxt, function ( key, value ) {
    if ( key === 'Date') { return new Date(); }
    //any additonal custom logic you may need later...
});

A general introduction to JSON-js is provided at the JSON in JavaScript page, along with some brief intro info about JSON, and the page also includes some usage scenarios.

Upvotes: 5

250R
250R

Reputation: 37151

You can consider leveraging popular library like moment.js http://momentjs.com/

Then you can store date as YYYY-MM-DD in json and let moment handle the parsing:

var dateString = '2012-11-01';
var someday = moment(dateString);
var formattedDate = someday.format('ddd, DD MMM YYYY'); // 'Thu, 01 Nov 2012'

Upvotes: 2

Javi
Javi

Reputation: 510

Wouldn't it be easier just to calculate the current system data whenever you read the file? I may be lacking context here but I don't see the point in storing that in the document.

If you really need to do so you can do as follows

var jsonObject = {"now":"new Date()"};
var date = eval(jsonObject.now);

Upvotes: 1

user1364925
user1364925

Reputation:

Server side can generate JSON dates in ISO format for example "2012-04-30T02:15:12.356Z" Then client side can parse and load into date object 

new Date(Date.parse("2012-04-30T02:15:12.356Z"))

Upvotes: 14

xgc1986
xgc1986

Reputation: 867

If you want to store the date, I would prefer to store as a String with a format like yyyy/mm/dd hh:mm:ss or something like that, and parse it in a Date object when I want to read it in the language I need.

obj = {
    dates : ['2012/04/30 10:14:23', '2012/05/01 05:34:01']
}

I don't understand exactly what you want, with eval methods (it's an ugly practice), you can add a method to puts the actual date in object, and also adds himself at the children and call the method added in the children. 

obj = {
    data : "foo",
    addDate : function() {
        this.date = newDate();
        if (this.children) {
            for (var i = 0; i < this.children.length; i++) {
                this.children[i].addDate = this.addDate;
                this.children[i].addDate();
            }
        }
    },
    children : [{
        data : "foo2"
    }]
}

PS if you want to store it in a file, then you have to use the eval method (not recommended) storing the methods as a string or evry time you load the file do

jsonLoaded; // this var has the json that you store in a file;
var addDate = function() {
    this.date = newDate();
    if (this.children) {
        for (var i = 0; i < this.children.length; i++) {
            this.children[i].addDate = this.addDate;
            this.children[i].addDate();
        }
    }
    this.addDate = null; // remove the function we have added
    // delete this.addDate; // if is compatible with browser
}
jsonLoaded.addDate = addDate;
jsonLoaded.addDate();

you cannot stringify json objects with functions, because of this, in the second method after add the method addDate, we remove that from the json object (also you can do delete this.addDate, but i don't know if it works in IE)

Upvotes: 1

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