Adding data dynamically from one json object to another

问题

Suppose i have a json object friends as:

{
   title: Friends
   link: /friends.json
   description: "My friends"
   people: [
   {
   id: "1",
   name: "Matthew",
   img: "img/matthew.jpg"
   },
   {
   id: "2",
   name:"Matt",
   img: "img/matt.jpg"
   },
   {
   id: "3",
   name: "David",
   img: "img/dav.jpg"
   }
   ]
}

This is stored as a file friends.json

Now using javascript/jQuery, i need to create a new object good_friends.json and need to add values (DYNAMICALLY and one-by-one) to it from "people" field of friends.json using the "people.id". How can i do that?

回答1:

You're pretty much going to need a server-side process if you want to save your changes.

You can load the JSON via ajax:

$.ajax({
    url: "/path/to/friends.json",
    dataType: "json",
    success: function(data) {
        // Here, `data` will be the object resulting from deserializing the JSON
        // Store `data` somewhere useful, perhaps you might have a `friends`
        // variable declared somewhere; if so:
        friends = data;
    },
    error: function() {
       // Handle the error
    }
});

To add to the deserialized object, you just modify it in memory:

friends.people.push({
    id: String(friends.people.length + 1),
    name: "John",
    img: "img/john.jpg"
});

Of course, those values will probably come from input fields or something, e.g.:

function addPerson() {
    friends.people.push({
        id: String(friends.people.length + 1),
        name: $("#nameField").val(),
        img: $("#imgField").val()
    });
}

Now you have an in-memory copy of your data. To store it somewhere, you have to have a server-side process you can post it to. You'd probably serialize it before posting, e.g., via JSON.stringify or similar. If your browser doesn't have JSON.stringify natively (most modern ones do, some older ones don't), you can use Crockford's.

Or if this is just for your own use, you could display the stringified result in a text field and the use copy-and-paste to paste it into friends.json in a text editor.

Here's a complete example, which shows the JSON in a text area: Live copy | source

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Test Page</title>
<style>
  body {
    font-family: sans-serif;
  }
</style>
</head>
<body>
  <label>Name:
    <input type="text" id="nameField">
  </label>
  <br><label>Img:
    <input type="text" id="imgField">
  </label>
  <br><input type="button" id="btnAdd" value="Add" disabled>
  <input type="button" id="btnShow" value="Show JSON" disabled>
  <br><div id="msg">&nbsp;</div>
  <hr>
  <textarea id="showField" rows="10" cols="60"></textarea>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script>
// Note that all of our script tags are at the end of the
// document. This lets the page load as quickly as possible
// and means we don't have to worry about whether the elements
// have been created yet (they have, because the scripts are
// below them).

// Put all of our code inside a function so we don't
// create globals
(function($) {
    if (typeof JSON === "undefined") {
        // Load Crockford's json2.js
        // NOTE: You'd want to use your own copy, not a hotlink
        // to his github like this.
        var scr = document.createElement('script');
        scr.src = "https://raw.github.com/douglascrockford/JSON-js/master/json2.js";
        document.documentElement.appendChild(scr);
    }

    var friends; // Where our deserialized friends.json will go

    // Focus the first field
    $("#nameField").focus();

    // Load the JSON
    $.ajax({
        url: "http://jsbin.com/ojexuz",
        dataType: "json",
        success: function(data) {
            // Here, `data` will be the object resulting from deserializing the JSON
            // Store `data` somewhere useful, perhaps you might have a `friends`
            // variable declared somewhere; if so:
            friends = data;

            // Enable our buttons now that we have data
            $("input[type='button']").prop("disabled", "");
        },
        error: function() {
            // Handle the error
            alert("Error loading friends.json");
        }
    });

    // Handle clicks on the "Add" button
    $("#btnAdd").click(function() {
        var nameField = $("#nameField"),
            imgField  = $("#imgField"),
            name      = $.trim(nameField.val()),
            img       = $.trim(imgField.val());
        if (!name || !img) {
            alert("Please supply both name and image");
            return;
        }
        addPerson(name, img);
        $("#msg").text("Added '" + name + "'");
        nameField.focus();
    });

    // An "add this person" function
    function addPerson(name, img) {
        friends.people.push({
            id:   String(friends.people.length + 1),
            name: name,
            img:  img
        });
    }

    // Handle clicks on the "Show" button
    $("#btnShow").click(function() {
        $("#showField").val(JSON.stringify(friends));
    });

})(jQuery);
</script>
</body>
</html>

来源：https://stackoverflow.com/questions/11078630/adding-data-dynamically-from-one-json-object-to-another

标签

javascript

jquery

json

dynamically-generated