96 lines
3.0 KiB
JavaScript
96 lines
3.0 KiB
JavaScript
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/*
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* Timemap.js Copyright 2008 Nick Rabinowitz.
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* Licensed under the MIT License (see LICENSE.txt)
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*/
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/**
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* @fileOverview
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* Metaweb Loader
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*
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* @author Nick Rabinowitz (www.nickrabinowitz.com)
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*/
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/*----------------------------------------------------------------------------
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* Loader
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*
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*/
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/**
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* @class
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* Metaweb loader factory - inherits from jsonp loader
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*
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* <p>This is a loader for data from the Metaweb service at freebase.com. See
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* the API documentation at <a href="http://www.freebase.com/view/en/documentation">http://www.freebase.com/view/en/documentation</a> for
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* a description of how to write MQL queries. This code is based on code from
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* the API site.</p>
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*
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* <p>Depends on:</p>
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* <ul>
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* <li>lib/json2.pack.js</li>
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* <li>loaders/jsonp.js</li>
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* </ul>
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*
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* @example Usage in TimeMap.init():
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datasets: [
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{
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title: "Freebase Dataset",
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type: "metaweb",
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options: {
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query: [
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{
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// query here - see Metaweb API
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}
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],
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transformFunction: function(data) {
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// map returned data to the expected format - see
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// http://code.google.com/p/timemap/wiki/JsonFormat
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return data;
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}
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}
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}
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]
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*
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* @param {Object} options All options for the loader:<pre>
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* {Object} query MQL query to load
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* {Function} preloadFunction Function to call on data before loading
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* {Function} transformFunction Function to call on individual items before loading
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* </pre>
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* @return {TimeMap.loaders.remote} Remote loader configured for MetaWeb
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*/
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TimeMap.loaders.metaweb = function(options) {
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var loader = new TimeMap.loaders.jsonp(options);
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// Host and service - default to freebase.com
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loader.HOST = options.host || "http://www.freebase.com";
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loader.QUERY_SERVICE = options.service || "/api/service/mqlread";
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// Metaweb preload functon
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loader.preload = function(data) {
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// Open outer envelope
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var innerEnvelope = data.qname;
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// Make sure the query was successful
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if (innerEnvelope.code.indexOf("/api/status/ok") != 0) {
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// uncomment for debugging
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/*
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// If error, get error message and throw
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var error = innerEnvelope.messages[0];
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throw error.code + ": " + error.message;
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*/
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return [];
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}
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// Get result from inner envelope
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var result = innerEnvelope.result;
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return result;
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};
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// format the query URL for Metaweb
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var q = options.query || {};
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var querytext = encodeURIComponent(JSON.stringify({qname: {query: q}}));
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// Build the URL using encoded query text and the callback name
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loader.url = loader.HOST + loader.QUERY_SERVICE + "?queries=" + querytext + "&callback=";
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return loader;
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}
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