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<title>Example: Adding New Object Members During Parsing</title>
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<h1>Example: Adding New Object Members During Parsing</h1>
<div class="yui3-g">
<div class="yui3-u-3-4">
<div id="main">
<div class="content"><div class="intro">
<p>
This example shows how to use the <code>reviver</code> parameter in <code>JSON.parse()</code> to add new object members and format existing members during the parsing phase.
</p>
</div>
<div class="example yui3-skin-sam">
<div id="demo">
<p>Choose a currency, then get the data</p>
<select>
<option value="ARS">Argentine Peso</option>
<option value="AUD">Australian Dollar</option>
<option value="BRL">Brazilian Real</option>
<option value="GBP">British Pound</option>
<option value="CAD">Canadian Dollar</option>
<option value="CNY">Chinese Yuan</option>
<option value="COP">Colombian Peso</option>
<option value="HRK">Croatian Kuna</option>
<option value="CZK">Czech Koruna</option>
<option value="DKK">Danish Krone</option>
<option value="EEK">Estonian Kroon</option>
<option value="EUR">Euro</option>
<option value="HKD">Hong Kong Dollar</option>
<option value="HUF">Hungarian Forint</option>
<option value="ISK">Iceland Krona</option>
<option value="INR">Indian Rupee</option>
<option value="JPY">Japanese Yen</option>
<option value="KRW">Korean Won</option>
<option value="LVL">Latvian Lat</option>
<option value="LTL">Lithuanian Lita</option>
<option value="MYR">Malaysian Ringgit</option>
<option value="MXN">Mexican Peso</option>
<option value="NZD">New Zealand Dollar</option>
<option value="NOK">Norwegian Krone</option>
<option value="PHP">Philippine Peso</option>
<option value="PLN">Polish Zloty</option>
<option value="RUB">Russian Rouble</option>
<option value="SGD">Singapore Dollar</option>
<option value="SKK">Slovak Koruna</option>
<option value="ZAR">South African Rand</option>
<option value="LKR">Sri Lanka Rupee</option>
<option value="SEK">Swedish Krona</option>
<option value="TRY">Turkey Lira</option>
<option value="USD" selected="selected">U.S. Dollar</option>
<option value="CHF">Swiss Franc</option>
<option value="TWD">Taiwan Dollar</option>
<option value="THB">Thai Baht</option>
</select>
<input type="button" id="demo_go" value="Get Data">
<table cellspacing="0">
<caption>Inventory</caption>
<thead>
<tr>
<th>SKU</th>
<th>Item</th>
<th>Price (USD)</th>
<th>Price (<span>USD</span>)</th>
</tr>
</thead>
<tbody>
<tr><td colspan="4">Click <em>Get Data</em></td></tr>
</tbody>
</table>
</div>
<script>
YUI().use("node", "io", "json-parse",function (Y) {
// Safari 4.0.3's native JSON does not support adding members during parse,
// so use JavaScript implementation for consistency
Y.JSON.useNativeParse = false;
var example = {
rates : {"USD":1,"EUR":0.6661,"GBP":0.5207,"AUD":1.1225,"BRL":1.609,"NZD":1.4198,"CAD":1.0667,"CHF":1.0792,"CNY":6.8587 ,"DKK":4.9702,"HKD":7.8064,"INR":42.0168,"JPY":109.8901,"KRW":1000,"LKR":107.5269,"MXN":10.1317,"MYR" :3.3167,"NOK":5.3277,"SEK":6.2617,"SGD":1.4073,"THB":33.7838,"TWD":31.1526,"VEF":2.1445,"ZAR":7.6923 ,"BGN":1.3028,"CZK":16.0514,"EEK":10.4275,"HUF":158.7302,"LTL":2.2999,"LVL":0.4692,"PLN":2.1758,"RON" :2.3804,"SKK":20.2429,"ISK":4.8008,"HRK":81.3008,"RUB":24.3309,"TRY":1.1811,"PHP":44.2478,"COP":2000 ,"ARS":3.1289},
currency : 'USD',
convert : function (k,v) {
// 'this' will refer to the object containing the key:value pair,
// so this step will add a new object member while leaving the original
// intact (but formatted to two decimal places). If the original
// is not needed, just return the converted value.
if (k === 'Price') {
var x = Math.round(v * example.rates[example.currency] * 100) / 100;
this.convertedPrice = x.toFixed(2); // added to item
return v.toFixed(2); // assigned to item.Price
}
return v;
},
updateTable : function (inventory) {
// Update the column header
Y.one('#demo table th span').set('innerHTML',example.currency);
var tbody = Y.one('#demo table tbody'),
html = ['<table><tbody>'],
rowTemplate = '<tr><td>{SKU}</td><td>{Item}</td><td>{Price}</td><td>{convertedPrice}</td></tr>',
i, len;
if (inventory) {
for (i = 0, len = inventory.length; i < len; ++i) {
html.push(Y.Lang.sub(rowTemplate, inventory[i]));
}
} else {
html.push('<tr><td colspan="4">No Inventory data</td></tr>');
}
html.push('</tbody></table>');
tbody.replace(Y.Node.create(html.join('')).one('tbody'));
}
};
Y.one('#demo_go').on('click', function (e) {
// Disable the button temporarily
this.set('disabled',true);
// Store the requested currency
var sel = Y.one("#demo select");
example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value");
Y.io('../assets/json/json-convert-values-response.json',{
timeout : 3000,
on : {
success : function (xid, res) {
var inventory;
try {
inventory = Y.JSON.parse(res.responseText,example.convert);
example.updateTable(inventory);
}
catch(e) {
alert("Error getting inventory data");
}
finally {
Y.one('#demo_go').set('disabled',false);
}
},
failure : function () {
alert("Error getting inventory data");
}
}
});
});
// Expose example objects for inspection
YUI.example = example;
});
</script>
</div>
<h2>The Data</h2>
<p>
The data returned from the server will be a JSON string containing this object structure:
</p>
<pre class="code prettyprint lang-json">[
{"SKU":"23-23874", "Price":23.99, "Item":"Helmet"},
{"SKU":"48-38835", "Price":14.97, "Item":"Football"},
{"SKU":"84-84848", "Price":3.49, "Item":"Goggles"},
{"SKU":"84-84843", "Price":183, "Item":"Badminton Set"},
{"SKU":"84-39321", "Price":6.79, "Item":"Tennis Balls"},
{"SKU":"39-48949", "Price":618, "Item":"Snowboard"},
{"SKU":"99-28128", "Price":78.99, "Item":"Cleats"},
{"SKU":"83-48281", "Price":4.69, "Item":"Volleyball"},
{"SKU":"89-32811", "Price":0.59, "Item":"Sweatband"},
{"SKU":"28-22847", "Price":779.98, "Item":"Golf Set"},
{"SKU":"38-38281", "Price":8.25, "Item":"Basketball Shorts"},
{"SKU":"82-38333", "Price":1.39, "Item":"Lip balm"},
{"SKU":"21-38485", "Price":0.07, "Item":"Ping Pong ball"},
{"SKU":"83-38285", "Price":3.99, "Item":"Hockey Puck"}
]</pre>
<h2>Create a <code>reviver</code> function</h2>
<p>
We'll contain all the moving parts in an <code>example</code> namespace. In it, we'll include the currency exchange rates and a function to reference the rates to add a new member to the JSON response as it is being parsed.
</p>
<pre class="code prettyprint">YUI().use("node", "io", "json-parse",function (Y) {
var example = {
rates : {"USD":1,"EUR":0.6661,...,"COP":2000 ,"ARS":3.1289},
currency : 'USD', // updated by the select element
convert : function (k,v) {
// 'this' will refer to the object containing the key:value pair,
// so this step will add a new object member while leaving the original
// intact (but formatted to two decimal places). If the original
// is not needed, just return the converted value.
if (k === 'Price') {
var x = Math.round(v * example.rates[example.currency] * 100) / 100;
this.convertedPrice = x.toFixed(2); // added to item
return v.toFixed(2); // assigned to item.Price
}
return v;
},
…
};
…</pre>
<h2>Sending the request and parsing the JSON response</h2>
<p>
When the <em>Get Data</em> button is clicked, we send an io request for the JSON data, and in our <code>success</code> handler, pass our conversion function to <code>JSON.parse()</code> with the response text. The resulting inventory records will have an additional member, <code>convertedPrice</code>. This data is then passed to a UI method to update the inventory table.
</p>
<pre class="code prettyprint">Y.one('#demo_go').on('click', function (e) {
// Disable the button temporarily
this.set('disabled',true);
// Store the requested currency
var sel = Y.one("#demo select");
example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value");
// Send the request for the JSON data
Y.io('../assets/json/json-convert-values-response.json',{
timeout : 3000,
on : {
success : function (xid, res) {
var inventory;
try {
inventory = Y.JSON.parse(res.responseText,example.convert);
example.updateTable(inventory);
}
catch(e) {
alert("Error getting inventory data");
}
finally {
Y.one('#demo_go').set('disabled',false);
}
},
failure : function () {
alert("Error getting inventory data");
}
}
});
});
}); // End YUI(..).use(..,function (Y) {</pre>
<h2>Complete Example Source</h2>
<pre class="code prettyprint"><div id="demo">
<p>Choose a currency, then get the data</p>
<select>
<option value="ARS">Argentine Peso</option>
<option value="AUD">Australian Dollar</option>
<option value="BRL">Brazilian Real</option>
<option value="GBP">British Pound</option>
<option value="CAD">Canadian Dollar</option>
<option value="CNY">Chinese Yuan</option>
<option value="COP">Colombian Peso</option>
<option value="HRK">Croatian Kuna</option>
<option value="CZK">Czech Koruna</option>
<option value="DKK">Danish Krone</option>
<option value="EEK">Estonian Kroon</option>
<option value="EUR">Euro</option>
<option value="HKD">Hong Kong Dollar</option>
<option value="HUF">Hungarian Forint</option>
<option value="ISK">Iceland Krona</option>
<option value="INR">Indian Rupee</option>
<option value="JPY">Japanese Yen</option>
<option value="KRW">Korean Won</option>
<option value="LVL">Latvian Lat</option>
<option value="LTL">Lithuanian Lita</option>
<option value="MYR">Malaysian Ringgit</option>
<option value="MXN">Mexican Peso</option>
<option value="NZD">New Zealand Dollar</option>
<option value="NOK">Norwegian Krone</option>
<option value="PHP">Philippine Peso</option>
<option value="PLN">Polish Zloty</option>
<option value="RUB">Russian Rouble</option>
<option value="SGD">Singapore Dollar</option>
<option value="SKK">Slovak Koruna</option>
<option value="ZAR">South African Rand</option>
<option value="LKR">Sri Lanka Rupee</option>
<option value="SEK">Swedish Krona</option>
<option value="TRY">Turkey Lira</option>
<option value="USD" selected="selected">U.S. Dollar</option>
<option value="CHF">Swiss Franc</option>
<option value="TWD">Taiwan Dollar</option>
<option value="THB">Thai Baht</option>
</select>
<input type="button" id="demo_go" value="Get Data">
<table cellspacing="0">
<caption>Inventory</caption>
<thead>
<tr>
<th>SKU</th>
<th>Item</th>
<th>Price (USD)</th>
<th>Price (<span>USD</span>)</th>
</tr>
</thead>
<tbody>
<tr><td colspan="4">Click <em>Get Data</em></td></tr>
</tbody>
</table>
</div>
<script>
YUI().use("node", "io", "json-parse",function (Y) {
// Safari 4.0.3's native JSON does not support adding members during parse,
// so use JavaScript implementation for consistency
Y.JSON.useNativeParse = false;
var example = {
rates : {"USD":1,"EUR":0.6661,"GBP":0.5207,"AUD":1.1225,"BRL":1.609,"NZD":1.4198,"CAD":1.0667,"CHF":1.0792,"CNY":6.8587 ,"DKK":4.9702,"HKD":7.8064,"INR":42.0168,"JPY":109.8901,"KRW":1000,"LKR":107.5269,"MXN":10.1317,"MYR" :3.3167,"NOK":5.3277,"SEK":6.2617,"SGD":1.4073,"THB":33.7838,"TWD":31.1526,"VEF":2.1445,"ZAR":7.6923 ,"BGN":1.3028,"CZK":16.0514,"EEK":10.4275,"HUF":158.7302,"LTL":2.2999,"LVL":0.4692,"PLN":2.1758,"RON" :2.3804,"SKK":20.2429,"ISK":4.8008,"HRK":81.3008,"RUB":24.3309,"TRY":1.1811,"PHP":44.2478,"COP":2000 ,"ARS":3.1289},
currency : 'USD',
convert : function (k,v) {
// 'this' will refer to the object containing the key:value pair,
// so this step will add a new object member while leaving the original
// intact (but formatted to two decimal places). If the original
// is not needed, just return the converted value.
if (k === 'Price') {
var x = Math.round(v * example.rates[example.currency] * 100) / 100;
this.convertedPrice = x.toFixed(2); // added to item
return v.toFixed(2); // assigned to item.Price
}
return v;
},
updateTable : function (inventory) {
// Update the column header
Y.one('#demo table th span').set('innerHTML',example.currency);
var tbody = Y.one('#demo table tbody'),
html = ['<table><tbody>'],
rowTemplate = '<tr><td>{SKU}</td><td>{Item}</td><td>{Price}</td><td>{convertedPrice}</td></tr>',
i, len;
if (inventory) {
for (i = 0, len = inventory.length; i < len; ++i) {
html.push(Y.Lang.sub(rowTemplate, inventory[i]));
}
} else {
html.push('<tr><td colspan="4">No Inventory data</td></tr>');
}
html.push('</tbody></table>');
tbody.replace(Y.Node.create(html.join('')).one('tbody'));
}
};
Y.one('#demo_go').on('click', function (e) {
// Disable the button temporarily
this.set('disabled',true);
// Store the requested currency
var sel = Y.one("#demo select");
example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value");
Y.io('../assets/json/json-convert-values-response.json',{
timeout : 3000,
on : {
success : function (xid, res) {
var inventory;
try {
inventory = Y.JSON.parse(res.responseText,example.convert);
example.updateTable(inventory);
}
catch(e) {
alert("Error getting inventory data");
}
finally {
Y.one('#demo_go').set('disabled',false);
}
},
failure : function () {
alert("Error getting inventory data");
}
}
});
});
// Expose example objects for inspection
YUI.example = example;
});
</script></pre>
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<h2 class="no-toc">Examples</h2>
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<ul class="examples">
<li data-description="Use JSON to parse data received via XMLHttpRequest via Y.io calls — a simple JSON use case.">
<a href="json-connect.html">JSON with Y.io</a>
</li>
<li data-description="Use the replacer and reviver parameters to reconstitute object instances that have been serialized to JSON.">
<a href="json-freeze-thaw.html">Rebuilding Class Instances from JSON Data</a>
</li>
<li data-description="Use a currency conversion calculation to add a new price member to a JSON response, demonstrating how JSON data, once retrieved, can be transformed during parsing.">
<a href="json-convert-values.html">Adding New Object Members During Parsing</a>
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<li data-description="A basic todo list built with the Model, Model List, and View components.">
<a href="../app/app-todo.html">Todo List</a>
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<li data-description="Portal style example using Drag & Drop Event Bubbling and Animation.">
<a href="../dd/portal-drag.html">Portal Style Example</a>
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YUI.Env.Tests.examples.push('json-connect');
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