Usa JSON en el protocolo de datos de Google
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Advertencia: Esta página trata sobre las API anteriores de Google, las API de datos de Google, y solo es relevante para las API que aparecen en el directorio de las API de datos de Google, muchas de las cuales se reemplazaron con API más nuevas. Para obtener información sobre una API nueva específica, consulta la documentación de la API nueva. Para obtener información sobre cómo autorizar solicitudes con una API más reciente, consulta Autenticación y autorización de cuentas de Google.
Este artículo abarca JSON, ya que se utiliza en el protocolo de datos de Google. Para obtener más información sobre el protocolo, consulta la guía para programadores.
Puedes usar JSON con cualquier lenguaje de programación, pero los ejemplos de este documento están en JavaScript.
Acerca de los feeds en formato JSON y XML
Un servicio de datos de Google crea un feed en formato JSON convirtiendo el feed XML mediante las siguientes reglas:
Básico
- El feed se representa como un objeto JSON; cada elemento o atributo anidado se representa como una propiedad de nombre/valor del objeto.
- Los atributos se convierten en propiedades de string.
- Los elementos secundarios se convierten en propiedades de objeto.
- Los elementos que pueden aparecer más de una vez se convierten en propiedades de arreglo.
- Los valores de texto de las etiquetas se convierten en propiedades
$t.
Espacio de nombres
- Si un elemento tiene un alias de espacio de nombres, el alias y el elemento se concatenan con “$”. Por ejemplo,
ns:element se convierte en ns$element.
XML
- La versión XML y los atributos de codificación se convierten en atributos de versión y codificación del elemento raíz, respectivamente.
En el siguiente ejemplo, se muestran las versiones XML y JSON del mismo feed. Tiene pestañas para facilitar la comparación.
XML
<?xml version="1.0" encoding="UTF-8" ?>
<feed xmlns="http://www.w3.org/2005/Atom"
xmlns:openSearch="http://a9.com/-/spec/opensearchrss/1.0/"
xmlns:gd="http://schemas.google.com/g/2005"
xmlns:gCal="http://schemas.google.com/gCal/2005">
<id>...</id>
<updated>2006-11-12T21:25:30.000Z</updated>
<title type="text">Google Developer Events</title>
<subtitle type="text">The calendar contains information about upcoming
developer conferences at which Google will be speaking, along with
other developer-related events.</subtitle>
<link rel="http://schemas.google.com/g/2005#feed"
type="application/atom+xml" href="..." />
<link rel="self" type="application/atom+xml" href="..." />
<author>
<name>Google Developer Calendar</name>
<email>developer-calendar@google.com</email>
</author>
<generator version="1.0"
uri="http://www.google.com/calendar">Google Calendar</generator>
<openSearch:startIndex>1</openSearch:startIndex>
<openSearch:itemsPerPage>25</openSearch:itemsPerPage>
<gCal:timezone value="America/Los_Angeles" />
<entry>
<id>...</id>
<published>2006-11-12T21:25:30.000Z</published>
<updated>2006-11-12T21:25:30.000Z</updated>
<category scheme="..." term="..." />
<title type="text">WebmasterWorld PubCon 2006:
Google Developer Tools in General</title>
<content type="text">Google is sponsoring at
<a href="http://www.pubcon.com/">WebmasterWorld PubCon 2006</a>. Come and
visit us at the booth or join us for an evening demo reception where we
will be talking "5 ways to enhance your website with Google Code".
After all, it is Vegas, baby! See you soon.</content>
<link rel="alternate" type="text/html" href="..." title="alternate" />
<link rel="self" type="application/atom+xml" href="..." />
<author>
<name>Google Developer Calendar</name>
<email>developer-calendar@google.com</email>
</author>
<gCal:sendEventNotifications value="true" />
<gd:comments>
<gd:feedLink href="..." />
</gd:comments>
<gd:transparency value="..." />
<gd:eventStatus value="..." />
<gd:where valueString="3150 Paradise Road, Las Vegas, NV 89109" />
<gd:when startTime="2006-11-15" endTime="2006-11-17">
<gd:reminder minutes="10" />
</gd:when>
</entry>
...
</feed>
JSON
{
"version": "1.0",
"encoding": "UTF-8",
"feed": {
"xmlns": "http://www.w3.org/2005/Atom",
"xmlns$openSearch": "http://a9.com/-/spec/opensearchrss/1.0/",
"xmlns$gd": "http://schemas.google.com/g/2005",
"xmlns$gCal": "http://schemas.google.com/gCal/2005",
"id": {"$t": "..."},
"updated": {"$t": "2006-11-12T21:25:30.000Z"},
"title": {
"type": "text",
"$t": "Google Developer Events"
},
"subtitle": {
"type": "text",
"$t": "The calendar contains information about upcoming developer
conferences at which Google will be speaking, along with other
developer-related events."
},
"link": [{
"rel": "...",
"type": "application/atom+xml",
"href": "..."
},{
"rel": "self",
"type": "application/atom+xml",
"href": "..."
}],
"author": [{
"name": {"$t": "Google Developer Calendar"},
"email": {"$t": "developer-calendar@google.com"}
}],
"generator":{
"version": "1.0",
"uri": "http://www.google.com/calendar",
"$t": "Google Calendar"
},
"openSearch$startIndex": {"$t": "1"},
"openSearch$itemsPerPage": {"$t": "25"},
"gCal$timezone": {"value": "America/Los_Angeles"},
"entry": [{
"id": {"$t": "..."},
"published": {"$t": "2006-11-12T21:25:30.000Z"},
"updated": {"$t": "2006-11-12T21:25:30.000Z"},
"category": [{
"scheme": "...",
"term": "..."
}],
"title":{
"type": "text",
"$t": "WebmasterWorld PubCon 2006: Google Developer Tools in General"
},
"content": {
"type": "text",
"$t": "Google is sponsoring at
<a href="http://www.pubcon.com/">WebmasterWorld PubCon 2006</a>.
\nCome and visit us at the booth or join us for an evening demo
reception where we will be talking "5 ways to enhance your website
with Google Code".\nAfter all,\nit is Vegas, baby! See you soon."
},
"link": [{
"rel": "alternate",
"type": "text/html",
"href": "...",
"title": "alternate"
},{
"rel": "self",
"type": "application/atom+xml",
"href": "..."
}],
"author": [{
"name": {"$t": "Google Developer Calendar"},
"email": {"$t": "developer-calendar@google.com"}
}],
"gd$transparency": {"value": "http://schemas.google.com/g/2005#event.opaque"},
"gd$eventStatus": {"value": "http://schemas.google.com/g/2005#event.confirmed"},
"gd$comments": {"gd$feedLink": {"href": "..."}},
"gCal$sendEventNotifications": {"value": "true"},
"gd$when": [{
"startTime": "2006-11-15",
"endTime": "2006-11-17",
"gd$reminder": [{"minutes": "10"}]
}],
"gd$where": [{"valueString": "3150 Paradise Road,Las Vegas,NV 89109"}]},
}]
}
}
Cómo solicitar y usar feeds JSON
Atom es el formato predeterminado de los datos de Google. Si no especificas un parámetro alt en
tu solicitud, recibirás un feed de Atom.
Nota: Las bibliotecas cliente de datos de Google actualmente no admiten JSON.
Salida de JSON
Para solicitar una respuesta en formato JSON, usa el parámetro alt=json.
Por ejemplo, para solicitar el feed de calendario de programadores de Google en formato JSON, envía la siguiente consulta:
http://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json
Salida JSON en la secuencia de comandos
Para solicitar una respuesta que una el JSON en una etiqueta de secuencia de comandos, usa el parámetro alt=json-in-script y agrega una función de devolución de llamada mediante el parámetro callback=functionName.
http://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json-in-script&callback=myFunction
El uso de funciones de devolución de llamada te permite evitar algunos de los problemas de seguridad multidominio que podrías encontrar en el código JavaScript típico del cliente. Por lo general, los navegadores evitan que cargues archivos entre dominios debido a posibles brechas de seguridad y ataques de dominio cruzado que podrían producirse.
El formato JSON en secuencia de comandos te permite evitar estas restricciones mediante la carga de la respuesta en una etiqueta de secuencia de comandos en el cliente. Esto significa que puedes usar la respuesta en otras partes del código JavaScript en esa página.
El resultado de JSON se carga cuando se carga la página; no se necesitan otros trucos.
La aplicación de trabajo simple que se muestra a continuación demuestra esta técnica:
<h3>Upcoming Google Developer Events</h3>
<div id="agenda"></div>
<script>
function listEvents(root) {
var feed = root.feed;
var entries = feed.entry || [];
var html = ['<ul>'];
for (var i = 0; i < entries.length; ++i) {
var entry = entries[i];
var title = (entry.title.type == 'html') ? entry.title.$t : escape(entry.title.$t);
var start = (entry['gd$when']) ? entry['gd$when'][0].startTime : "";
html.push('<li>', start, ' ', title, '</li>');
}
html.push('</ul>');
document.getElementById("agenda").innerHTML = html.join("");
}
</script>
<script src="http://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json-in-script&callback=listEvents">
</script>
Ejemplos
Para ver ejemplos prácticos de cómo usar JSON con las API de datos de Google, consulta la página de muestras.
Recursos adicionales
Existen varios recursos externos que te recomendamos consultar para obtener más información sobre JSON y el uso de JSON en aplicaciones web.
Volver al principio
Salvo que se indique lo contrario, el contenido de esta página está sujeto a la licencia Atribución 4.0 de Creative Commons, y los ejemplos de código están sujetos a la licencia Apache 2.0. Para obtener más información, consulta las políticas del sitio de Google Developers. Java es una marca registrada de Oracle o sus afiliados.
Última actualización: 2023-03-01 (UTC)
[[["Fácil de comprender","easyToUnderstand","thumb-up"],["Resolvió mi problema","solvedMyProblem","thumb-up"],["Otro","otherUp","thumb-up"]],[["Falta la información que necesito","missingTheInformationINeed","thumb-down"],["Muy complicado o demasiados pasos","tooComplicatedTooManySteps","thumb-down"],["Desactualizado","outOfDate","thumb-down"],["Problema de traducción","translationIssue","thumb-down"],["Problema con las muestras o los códigos","samplesCodeIssue","thumb-down"],["Otro","otherDown","thumb-down"]],["Última actualización: 2023-03-01 (UTC)"],[[["\u003cp\u003eThis document explains how to use JSON with the older Google Data APIs to request and utilize data feeds.\u003c/p\u003e\n"],["\u003cp\u003eGoogle Data services can provide data in JSON format by converting XML feeds using specific rules for elements, attributes, and namespaces.\u003c/p\u003e\n"],["\u003cp\u003eTo request JSON output, use the \u003ccode\u003ealt=json\u003c/code\u003e parameter in your API request URL.\u003c/p\u003e\n"],["\u003cp\u003eFor JSON wrapped in a script tag (useful for cross-domain requests), use \u003ccode\u003ealt=json-in-script\u003c/code\u003e and a callback function with \u003ccode\u003ecallback=*functionName*\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe provided JavaScript example demonstrates fetching and displaying Google Calendar event data using JSON-in-script.\u003c/p\u003e\n"]]],[],null,["# Using JSON in the Google Data Protocol\n\n**Warning** : This page is about Google's older APIs, the Google Data APIs; it's relevant only to the APIs that are listed in the [Google Data APIs directory](/gdata/docs/directory), many of which have been replaced with newer APIs. For information about a specific new API, see the new API's documentation. For information about authorizing requests with a newer API, see [Google Accounts Authentication and Authorization](/accounts).\n\nThis article covers JSON as it is used within the Google Data Protocol. For more\ninformation about the protocol, view the [Developer's Guide](/gdata/docs/developers-guide).\n\nYou can use JSON with any programming language, but the examples in this document are in JavaScript.\n\nAbout JSON feeds and XML feeds\n==============================\n\nA Google Data service creates a JSON-format feed by converting the XML feed using the following rules:\n\n**Basic**\n\n- The feed is represented as a JSON object; each nested element or attribute is represented as a name/value property of the object.\n- Attributes are converted to String properties.\n- Child elements are converted to Object properties.\n- Elements that may appear more than once are converted to Array properties.\n- Text values of tags are converted to `$t` properties.\n\n**Namespace**\n\n- If an element has a namespace alias, the alias and element are concatenated using \"$\". For example, `ns:element` becomes `ns$element`.\n\n**XML**\n\n- XML version and encoding attributes are converted to version and encoding attributes of the root element, respectively.\n\nThe following example shows XML and JSON versions of the same feed. They are tabbed to provide easy comparison. \n\n### XML\n\n```\n\u003c?xml version=\"1.0\" encoding=\"UTF-8\" ?\u003e\n\u003cfeed xmlns=\"http://www.w3.org/2005/Atom\"\n xmlns:openSearch=\"http://a9.com/-/spec/opensearchrss/1.0/\"\n xmlns:gd=\"http://schemas.google.com/g/2005\"\n xmlns:gCal=\"http://schemas.google.com/gCal/2005\"\u003e\n \u003cid\u003e...\u003c/id\u003e\n \u003cupdated\u003e2006-11-12T21:25:30.000Z\u003c/updated\u003e\n \u003ctitle type=\"text\"\u003eGoogle Developer Events\u003c/title\u003e\n \u003csubtitle type=\"text\"\u003eThe calendar contains information about upcoming\n developer conferences at which Google will be speaking, along with\n other developer-related events.\u003c/subtitle\u003e\n \u003clink rel=\"http://schemas.google.com/g/2005#feed\"\n type=\"application/atom+xml\" href=\"...\" /\u003e\n \u003clink rel=\"self\" type=\"application/atom+xml\" href=\"...\" /\u003e\n \u003cauthor\u003e\n \u003cname\u003eGoogle Developer Calendar\u003c/name\u003e\n \u003cemail\u003edeveloper-calendar@google.com\u003c/email\u003e\n \u003c/author\u003e\n \u003cgenerator version=\"1.0\"\n uri=\"http://www.google.com/calendar\"\u003eGoogle Calendar\u003c/generator\u003e\n \u003copenSearch:startIndex\u003e1\u003c/openSearch:startIndex\u003e\n \u003copenSearch:itemsPerPage\u003e25\u003c/openSearch:itemsPerPage\u003e\n \u003cgCal:timezone value=\"America/Los_Angeles\" /\u003e\n \n \u003centry\u003e\n \u003cid\u003e...\u003c/id\u003e\n \u003cpublished\u003e2006-11-12T21:25:30.000Z\u003c/published\u003e\n \u003cupdated\u003e2006-11-12T21:25:30.000Z\u003c/updated\u003e\n \u003ccategory scheme=\"...\" term=\"...\" /\u003e\n \u003ctitle type=\"text\"\u003eWebmasterWorld PubCon 2006:\n Google Developer Tools in General\u003c/title\u003e\n \u003ccontent type=\"text\"\u003eGoogle is sponsoring at \n \u003ca href=\"http://www.pubcon.com/\"\u003eWebmasterWorld PubCon 2006\u003c/a\u003e. Come and\n visit us at the booth or join us for an evening demo reception where we\n will be talking \"5 ways to enhance your website with Google Code\". \n After all, it is Vegas, baby! See you soon.\u003c/content\u003e\n \u003clink rel=\"alternate\" type=\"text/html\" href=\"...\" title=\"alternate\" /\u003e\n \u003clink rel=\"self\" type=\"application/atom+xml\" href=\"...\" /\u003e\n \u003cauthor\u003e\n \u003cname\u003eGoogle Developer Calendar\u003c/name\u003e\n \u003cemail\u003edeveloper-calendar@google.com\u003c/email\u003e\n \u003c/author\u003e\n \u003cgCal:sendEventNotifications value=\"true\" /\u003e\n \u003cgd:comments\u003e\n \u003cgd:feedLink href=\"...\" /\u003e\n \u003c/gd:comments\u003e\n \u003cgd:transparency value=\"...\" /\u003e\n \u003cgd:eventStatus value=\"...\" /\u003e\n \u003cgd:where valueString=\"3150 Paradise Road, Las Vegas, NV 89109\" /\u003e\n \u003cgd:when startTime=\"2006-11-15\" endTime=\"2006-11-17\"\u003e\n \u003cgd:reminder minutes=\"10\" /\u003e\n \u003c/gd:when\u003e\n \u003c/entry\u003e\n ...\n\u003c/feed\u003e\n \n```\n\n### JSON\n\n```\n{\n \"version\": \"1.0\",\n \"encoding\": \"UTF-8\",\n \"feed\": {\n \"xmlns\": \"http://www.w3.org/2005/Atom\",\n \"xmlns$openSearch\": \"http://a9.com/-/spec/opensearchrss/1.0/\",\n \"xmlns$gd\": \"http://schemas.google.com/g/2005\",\n \"xmlns$gCal\": \"http://schemas.google.com/gCal/2005\",\n \"id\": {\"$t\": \"...\"},\n \"updated\": {\"$t\": \"2006-11-12T21:25:30.000Z\"},\n \"title\": {\n \"type\": \"text\",\n \"$t\": \"Google Developer Events\"\n },\n \"subtitle\": {\n \"type\": \"text\",\n \"$t\": \"The calendar contains information about upcoming developer \n conferences at which Google will be speaking, along with other \n developer-related events.\"\n },\n \"link\": [{\n \"rel\": \"...\",\n \"type\": \"application/atom+xml\",\n \"href\": \"...\"\n },{\n \"rel\": \"self\",\n \"type\": \"application/atom+xml\",\n \"href\": \"...\"\n }],\n \"author\": [{\n \"name\": {\"$t\": \"Google Developer Calendar\"},\n \"email\": {\"$t\": \"developer-calendar@google.com\"}\n }],\n \"generator\":{\n \"version\": \"1.0\",\n \"uri\": \"http://www.google.com/calendar\",\n \"$t\": \"Google Calendar\"\n },\n \"openSearch$startIndex\": {\"$t\": \"1\"},\n \"openSearch$itemsPerPage\": {\"$t\": \"25\"},\n \"gCal$timezone\": {\"value\": \"America/Los_Angeles\"},\n\n \"entry\": [{\n \"id\": {\"$t\": \"...\"},\n \"published\": {\"$t\": \"2006-11-12T21:25:30.000Z\"},\n \"updated\": {\"$t\": \"2006-11-12T21:25:30.000Z\"},\n \"category\": [{\n \"scheme\": \"...\",\n \"term\": \"...\"\n }],\n \"title\":{\n \"type\": \"text\",\n \"$t\": \"WebmasterWorld PubCon 2006: Google Developer Tools in General\"\n },\n \"content\": {\n \"type\": \"text\",\n \"$t\": \"Google is sponsoring at\n \u003ca href=\"http://www.pubcon.com/\"\u003eWebmasterWorld PubCon 2006\u003c/a\u003e.\n \\nCome and visit us at the booth or join us for an evening demo\n reception where we will be talking \"5 ways to enhance your website\n with Google Code\".\\nAfter all,\\nit is Vegas, baby! See you soon.\"\n },\n \"link\": [{\n \"rel\": \"alternate\",\n \"type\": \"text/html\",\n \"href\": \"...\",\n \"title\": \"alternate\"\n },{\n \"rel\": \"self\",\n \"type\": \"application/atom+xml\",\n\t \"href\": \"...\"\n }],\n \"author\": [{\n \"name\": {\"$t\": \"Google Developer Calendar\"},\n \"email\": {\"$t\": \"developer-calendar@google.com\"}\n }],\n \"gd$transparency\": {\"value\": \"http://schemas.google.com/g/2005#event.opaque\"},\n \"gd$eventStatus\": {\"value\": \"http://schemas.google.com/g/2005#event.confirmed\"},\n \"gd$comments\": {\"gd$feedLink\": {\"href\": \"...\"}},\n \"gCal$sendEventNotifications\": {\"value\": \"true\"},\n \"gd$when\": [{\n \"startTime\": \"2006-11-15\",\n \"endTime\": \"2006-11-17\",\n \"gd$reminder\": [{\"minutes\": \"10\"}]\n }],\n \"gd$where\": [{\"valueString\": \"3150 Paradise Road,Las Vegas,NV 89109\"}]},\n }]\n }\n}\n```\n\nRequesting and using JSON feeds\n===============================\n\nAtom is Google Data's default format. If you don't specify an `alt` parameter in\nyour request, then you receive an Atom feed.\n\n**Note**: The Google Data client libraries don't currently support JSON.\n\n### JSON output\n\nTo request a response in JSON format, use the `alt=json` parameter.\n\nFor example, to request Google's developer calendar feed in JSON format, send the following query: \n\n```\nhttp://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json\n```\n\n### JSON-in-script output\n\nTo request a response that wraps JSON in a script tag, use the `alt=json-in-script`\nparameter and add a callback function by adding the `callback=`*functionName* parameter. \n\n```\nhttp://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json-in-script&callback=myFunction\n```\n\nUsing callback functions allows you get around some of the cross-domain\nsecurity issues you might encounter in typical client side JavaScript. Usually\nbrowsers prevent you from loading files across domains because of potential\nsecurity holes and the cross domain attacks that could result.\n\nThe JSON-in-script format allows you to get around these restrictions by\nloading the response in a script tag on the client. This means that you\ncan use the response in other places in your JavaScript code on that page.\nThe JSON output is loaded when the page is loaded; no other tricks are needed.\n\nThe simple working application below demonstrates this technique: \n\n```\n\u003ch3\u003eUpcoming Google Developer Events\u003c/h3\u003e\n\n\u003cdiv id=\"agenda\"\u003e\u003c/div\u003e\n\n\u003cscript\u003e\n function listEvents(root) {\n var feed = root.feed;\n var entries = feed.entry || [];\n var html = ['\u003cul\u003e'];\n\n for (var i = 0; i \u003c entries.length; ++i) {\n var entry = entries[i];\n var title = (entry.title.type == 'html') ? entry.title.$t : escape(entry.title.$t);\n var start = (entry['gd$when']) ? entry['gd$when'][0].startTime : \"\";\t\n\n html.push('\u003cli\u003e', start, ' ', title, '\u003c/li\u003e');\n }\n\n html.push('\u003c/ul\u003e');\n document.getElementById(\"agenda\").innerHTML = html.join(\"\");\n }\n\u003c/script\u003e\n\n\u003cscript src=\"http://www.google.com/calendar/feeds/developer-calendar@google.com/public/full?alt=json-in-script&callback=listEvents\"\u003e\n\u003c/script\u003e\n```\n\nSamples\n=======\n\nFor working examples of how to use JSON with the Google Data APIs, see the [samples](/gdata/samples) page.\n\nAdditional resources\n====================\n\nThere are several external resources that you may want to check out to learn more about JSON and using JSON in web applications.\n\n- [JSON.org](http://www.json.org/)\n- [Wikipedia entry on JSON](http://en.wikipedia.org/wiki/JSON)\n- [JSON: The Fat Free Alternative\n to XML](http://www.json.org/xml.html)\n\n[Back to top](#top)"]]
