Freebase API

Search Overview

  1. Overview
  2. Security considerations
  3. Advanced filtering

Overview

The Freebase Search API provides access to Freebase data given a free text query. The results of the query are ordered and have a numerical relevancy score.

Developers can apply filters to constrain the search results to certain types of data. See the Search Cookbook for more information on how to construct detailed search queries.

Some examples of how developers may want to use the Search API include:

The following code samples in several supported languages show how to perform a search for a musical artist that matches the text “Cee Lo Green”. An additional constraint is that they created something called “The Lady Killer”.

Python

import json
import urllib

api_key = open(".api_key").read()
query = 'blue bottle'
service_url = 'https://www.googleapis.com/freebase/v1/search'
params = {
	'query': query,
	'key': api_key
}
url = service_url + '?' + urllib.urlencode(params)
response = json.loads(urllib.urlopen(url).read())
for result in response['result']:
    print result['name'] + ' (' + str(result['score']) + ')'

Ruby

require 'rubygems'
require 'cgi'
require 'httparty'
require 'json'
require 'addressable/uri'

API_KEY = open(".freebase_api_key").read()
url = Addressable::URI.parse('https://www.googleapis.com/freebase/v1/search')
url.query_values = {
	'query' => 'Blue Bottle',
	'key'=> API_KEY
}
response = HTTParty.get(url, :format => :json)
response['result'].each { |topic|
  puts topic['name']
} 
This example uses the Httparty and Addressable libraries.

Java

package com.freebase.samples;

import com.google.api.client.http.GenericUrl;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpRequestFactory;
import com.google.api.client.http.HttpResponse;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.jayway.jsonpath.JsonPath;
import java.io.FileInputStream;
import java.util.Properties;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

public class SearchExample {
  public static Properties properties = new Properties();
  public static void main(String[] args) {
    try {
      properties.load(new FileInputStream("freebase.properties"));
      HttpTransport httpTransport = new NetHttpTransport();
      HttpRequestFactory requestFactory = httpTransport.createRequestFactory();
      JSONParser parser = new JSONParser();
      GenericUrl url = new GenericUrl("https://www.googleapis.com/freebase/v1/search");
      url.put("query", "Cee Lo Green");
      url.put("filter", "(all type:/music/artist created:\"The Lady Killer\")");
      url.put("limit", "10");
      url.put("indent", "true");
      url.put("key", properties.get("API_KEY"));
      HttpRequest request = requestFactory.buildGetRequest(url);
      HttpResponse httpResponse = request.execute();
      JSONObject response = (JSONObject)parser.parse(httpResponse.parseAsString());
      JSONArray results = (JSONArray)response.get("result");
      for (Object result : results) {
        System.out.println(JsonPath.read(result,"$.name").toString());
      }
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}

Javascript

<!DOCTYPE html>
<html>
<head>
    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
</head>
<body>
<script>
  var service_url = 'https://www.googleapis.com/freebase/v1/search';
  var params = {
    'query': 'Cee Lo Green',
    'filter': '(all type:/music/artist created:"The Lady Killer")',
    'limit': 10,
    'indent': true
  };
  $.getJSON(service_url + '?callback=?', params, function(response) {
    $.each(response.result, function(i, result) {
      $('<div>', {text:result['name']}).appendTo(document.body);
    });
  });
</script>
</body>
</html>
This example uses the jQuery library.

PHP

<!DOCTYPE html>
<html>
<body>
<?php
  include('.freebase-api-key');
  $service_url = 'https://www.googleapis.com/freebase/v1/search';
  $params = array(
    'query' => 'Blue Bottle',
    'key' => $freebase_api_key
  );
  $url = $service_url . '?' . http_build_query($params);
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  $response = json_decode(curl_exec($ch), true);
  curl_close($ch);
  foreach($response['result'] as $result) {
    echo $result['name'] . '<br/>';
  }
?>
</body>
</html>

Also see the Client Libraries page to see if your favorite language is supported.

Search API documentation

Also see the following documentation:

Security considerations

The Search API indexes and searches user generated content stored in the Freebase graph. This means that you cannot directly use the content on a web page without safely escaping it first.

See Getting Started: Security for more information.

Advanced filtering

The Search API supports a large number of filter constraints to better aim the search at the correct entities.

For example, using a "type" filter constraint, we can show a list of the most notable people in Freebase.

filter=(any type:/people/person)

Filter constraints accept a variety of inputs:

  • Human readable IDs for schema entities or users, for example:
    • /people/person for a type constraint
    • /film for a domain constraint
  • Freebase MIDs, for example:
    • /m/04kr for the same /people/person type constraint
    • /m/010s for the above /film domain constraint
  • Entity names, for example:
    • "person" for a less precise /people/person type constraint
    • "film" for a less precise /film domain constraint

Filter constraints can be classified into a few categories. See the Search Cookbook for more details.

Filter constraints can be freely combined and repeated in the SearchRequest directly. Repeated filter constraint parameters are combined into an OR query. Different filter constraint parameters or groups are combined into an AND query.

For example:

To search for "people or cities named Gore", try:

query=gore
&filter=(any type:/people/person type:/location/citytown)

This combining behavior can be overriden and better controlled with the filter parameter which offers a richer interface to combining constraints. It is an s-expression, possibly arbitrarily nested, where the operator is one of:

  • any, logically an OR
  • all, logically an AND
  • not
  • should, which can only be used at the top level and which denotes that the constraint is optional. During scoring, matches that don't match optional constraints have their score divided in half for each optional constraint they don't match.

For example:

To match on the /people/person type or the /film domain, try:

query=gore
&filter=(any type:/people/person domain:/film)

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