This post contains a C# class to search the internet using Google’s custom search API. Before using this class you must first create a Google account (link) and generate an API key (link).
Unfortunately, this code cannot be used directly from a Silverlight application because of security limitations (see cross domain policy). If you need this capability in a Silverlight web application I would suggest performing the search via an ASP.NET proxy (license permitting).
In this sample, I called the Google search API from a WPF application, but it would also work in a WinForms or ASP.NET application as suggested above.
Here is the XAML of the Window that displays the results of the Google search.
<Window x:Class="ESRI.PrototypeLab.MapServiceHarvester.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="600"
Width="800"
>
<Grid>
<DataGrid x:Name="DataGridResults" AutoGenerateColumns="True" />
</Grid>
</Window>
Here is the code behind that makes that performs the internet search and displays the results in the datagrid defined above.
public partial class MainWindow : Window {
public MainWindow() {
InitializeComponent();
this.Loaded += (s, e) => {
GoogleSearch search = new GoogleSearch() {
Key = "<enter your key here>",
CX = "013036536707430787589:_pqjad5hr1a"
};
search.SearchCompleted += (a, b) => {
this.DataGridResults.ItemsSource = b.Response.Items;
};
search.Search("gis");
};
}
}
And here is the class that calls Google’s custom search API, desterilizes the JSON response and returns the result as single .NET objects.
public class GoogleSearch {
public GoogleSearch() {
this.Num = 10;
this.Start = 1;
this.SafeLevel = SafeLevel.off;
}
//
// PROPERTIES
//
public string Key { get; set; }
public string CX { get; set; }
public int Num { get; set; }
public int Start { get; set; }
public SafeLevel SafeLevel { get; set; }
//
// EVENTS
//
public event EventHandler<SearchEventArgs> SearchCompleted;
//
// METHODs
//
protected void OnSearchCompleted(SearchEventArgs e) {
if (this.SearchCompleted != null) {
this.SearchCompleted(this, e);
}
}
public void Search(string search) {
// Check Parameters
if (string.IsNullOrWhiteSpace(this.Key)) {
throw new Exception("Google Search 'Key' cannot be null");
}
if (string.IsNullOrWhiteSpace(this.CX)) {
throw new Exception("Google Search 'CX' cannot be null");
}
if (string.IsNullOrWhiteSpace(search)) {
throw new ArgumentNullException("search");
}
if (this.Num < 0 || this.Num > 10) {
throw new ArgumentNullException("Num must be between 1 and 10");
}
if (this.Start < 1 || this.Start > 100) {
throw new ArgumentNullException("Start must be between 1 and 100");
}
// Build Query
string query = string.Empty;
query += string.Format("q={0}", search);
query += string.Format("&key={0}", this.Key);
query += string.Format("&cx={0}", this.CX);
query += string.Format("&safe={0}", this.SafeLevel.ToString());
query += string.Format("&alt={0}", "json");
query += string.Format("&num={0}", this.Num);
query += string.Format("&start={0}", this.Start);
// Construct URL
UriBuilder builder = new UriBuilder() {
Scheme = Uri.UriSchemeHttps,
Host = "www.googleapis.com",
Path = "customsearch/v1",
Query = query
};
// Submit Request
WebClient w = new WebClient();
w.DownloadStringCompleted += (a, b) => {
// Check for errors
if (b == null) { return; }
if (b.Error != null) { return; }
if (string.IsNullOrWhiteSpace(b.Result)) { return; }
// Desearealize from JSON to .NET objects
Byte[] bytes = Encoding.Unicode.GetBytes(b.Result);
MemoryStream memoryStream = new MemoryStream(bytes);
DataContractJsonSerializer dataContractJsonSerializer =
new DataContractJsonSerializer(typeof(GoogleSearchResponse));
GoogleSearchResponse googleSearchResponse =
dataContractJsonSerializer.ReadObject(memoryStream) as GoogleSearchResponse;
memoryStream.Close();
// Raise Event
this.OnSearchCompleted(
new SearchEventArgs() {
Response = googleSearchResponse
}
);
};
w.DownloadStringAsync(builder.Uri);
}
}
public enum SafeLevel { off, medium, high }
public class SearchEventArgs : EventArgs {
public GoogleSearchResponse Response { get; set; }
}
[DataContract]
public class GoogleSearchResponse {
[DataMember(Name = "kind")]
public string Kind { get; set; }
[DataMember(Name = "url")]
public Url Url { get; set; }
[DataMember(Name = "queries")]
public Queries Queries { get; set; }
[DataMember(Name = "context")]
public Context Context { get; set; }
[DataMember(Name = "items")]
public List<Item> Items { get; set; }
}
[DataContract]
public class Url {
[DataMember(Name = "type")]
public string Type { get; set; }
[DataMember(Name = "template")]
public string Template { get; set; }
}
[DataContract]
public class Queries {
[DataMember(Name = "nextPage")]
public List<Page> NextPage { get; set; }
[DataMember(Name = "request")]
public List<Page> Request { get; set; }
}
[DataContract]
public class Page {
[DataMember(Name = "title")]
public string Title { get; set; }
[DataMember(Name = "totalResults")]
public int Request { get; set; }
[DataMember(Name = "searchTerms")]
public string SearchTerms { get; set; }
[DataMember(Name = "count")]
public int Count { get; set; }
[DataMember(Name = "startIndex")]
public int StartIndex { get; set; }
[DataMember(Name = "inputEncoding")]
public string InputEncoding { get; set; }
[DataMember(Name = "outputEncoding")]
public string OutputEncoding { get; set; }
[DataMember(Name = "safe")]
public string Safe { get; set; }
[DataMember(Name = "cx")]
public string CX { get; set; }
}
[DataContract]
public class Context {
[DataMember(Name = "title")]
public string Title { get; set; }
[DataMember(Name = "facets")]
public List<List<Facet>> Facets { get; set; }
}
[DataContract]
public class Facet {
[DataMember(Name = "label")]
public string Label { get; set; }
[DataMember(Name = "anchor")]
public string Anchor { get; set; }
}
[DataContract]
public class Item {
[DataMember(Name = "kind")]
public string Kind { get; set; }
[DataMember(Name = "title")]
public string Title { get; set; }
[DataMember(Name = "htmlTitle")]
public string HtmlTitle { get; set; }
[DataMember(Name = "link")]
public string Link { get; set; }
[DataMember(Name = "displayLink")]
public string DisplayLink { get; set; }
[DataMember(Name = "snippet")]
public string Snippet { get; set; }
[DataMember(Name = "htmlSnippet")]
public string HtmlSnippet { get; set; }
[DataMember(Name = "cacheId")]
public string CacheId { get; set; }
//[DataMember(Name = "pagemap")] *** Cannot deserialize JSON to .NET! ***
//public Pagemap Pagemap { get; set; }
}
[DataContract]
public class Pagemap {
[DataMember(Name = "metatags")]
public List<Dictionary<string, string>> Metatags { get; set; }
}
[DataContract]
public class Metatag {
[DataMember(Name = "creationdate")]
public string Creationdate { get; set; }
[DataMember(Name = "moddate")]
public string Moddate { get; set; }
}
And lastly, here is the result.
The only issue I had with this sample was trying to deserialize the JSON associated with the “pagemap” property (see commented out code above). Any tips would be appreciated.
