DownloadStrinAsync error during parsing in Windows Phone - windows

Question

i've an issue... I would create an app that scraping the result of a google search.. but when I try to use downloadstringasync the debug return me an error "Impossible to assign 'void' to a local variable ..."
You say how I can resolve it?
This is the code
public class SearchResult
{
public string url;
public string title;
public string content;
public FindingEngine engine;
public enum FindingEngine { google, bing, google_and_bing };
public SearchResult(string url, string title, string content, FindingEngine engine)
{
this.url = url;
this.title = title;
this.content = content;
this.engine = engine;
}
}
public static List<SearchResult> GoogleSearch(string search_expression,
Dictionary<string, object> stats_dict)
{
var url_template = "http://ajax.googleapis.com/ajax/services/search/web?v=1.0&rsz=large&safe=active&q={0}&start={1}";
Uri search_url;
var results_list = new List<SearchResult>();
int[] offsets = { 0, 8, 16, 24, 32, 40, 48 };
foreach (var offset in offsets)
{
var searchUrl = new Uri(string.Format(url_template, search_expression, offset));
var page = new WebClient().DownloadStringAsync(searchUrl);
var o = (JObject)JsonConvert.DeserializeObject(page);
var results_query =
from result in o["responseData"]["results"].Children()
select new SearchResult(
url: result.Value<string>("url").ToString(),
title: result.Value<string>("title").ToString(),
content: result.Value<string>("content").ToString(),
engine: SearchResult.FindingEngine.google
);
foreach (var result in results_query)
results_list.Add(result);
}
return results_list;
}
Thanks!

Answer 1

DownloadStringAsync doesn't return anything i.e. a void so you cannot simply assign a variable to it.
You need to add an event handler to DownloadStringCompleted which will be fired when DownloadStringAsync completes.
var client = new WebClient();
client.DownloadStringCompleted += client_DownloadStringCompleted;
client.DownloadStringAsync(searchUrl);
static void client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e) {
// e.Result will contain the returned JSON. Move the code that parse the result to here.
}