WP8.1客户端代码中的HttpResponseMessage错误

Question

I have a problem that I can't seem to figure out with my WindowsPhone 8.1 app. On my client side, I'm writing code to retrieve the values from the database that I query. While I was able to successfully do that with my Bars entities, I can't seem to get my Teams entities to work. The weird thing is that it seems to both get past and get stuck on the creation of my HttpResponseMessage object. Here's the code:

private void refresh_Click(object sender, RoutedEventArgs e)
    {
        GetTeams();
        //getTeamById(10);
    }


    public async void GetTeams()
    {
        using (var client = new HttpClient())
        {
            teamsListBox.Items.Add("using block entered");
            client.BaseAddress = new Uri("http://nflff.azurewebsites.net");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            teamsListBox.Items.Add("client's defaultrequestheaders done");

            HttpResponseMessage response = await client.GetAsync("api/bars");//not getting past here
            teamsListBox.Items.Add("right after response"); //not printing
            if (response.IsSuccessStatusCode)
            {
                teamsListBox.Items.Add("if entered");
                //IList<Teams> Teams = await response.Content.ReadAsAsync<IList<Teams>>();
                string teams = await response.Content.ReadAsStringAsync();

                int start = 0;
                while (start != -1)
                {
                    start = stringToTeam(teams, start); //throwing exception inside stringToTeams, which isn't being called anywhere else
                }
            }
            teamsListBox.Items.Add(Teams.TeamsList.Count);
            foreach (var team in Teams.TeamsList)
            {
                teamsListBox.Items.Add(team.ToString());
            }
        }
    }

public int stringToTeam(String Team, int start)
    {
        start = Team.IndexOf("TeamID", start) + 8;
        int end = Team.IndexOf(",", start); //start index correct
        //teamsListBox.Items.Add(end);
        int id = Convert.ToInt32(Team.Substring(start, end - start)); //throws FormatException for string to DateTime
        //String id = Team.Substring(start, (end - start));
        teamsListBox.Items.Add("id is " + id);
        start = Team.IndexOf("TeamName", start) + 11;
        end = Team.IndexOf("\"", start);
        //teamsListBox.Items.Add(end);
        String name = Team.Substring(start, (end - start));
        teamsListBox.Items.Add("name is " + name);

        String city = Team.Substring(start, (end - start));
        teamsListBox.Items.Add("city is " + city);
        start = Team.IndexOf("TeamState", start) + 12;
        end = Team.IndexOf("\"", start);
        //teamsListBox.Items.Add(end);


        //creates a Teams model obj with values pulled from string and adds it to static list of objs in Teams model
        //teamsListBox.Items.Add(Teams.TeamsList.Count);
        Teams newTeam = new Teams(id, name, city);
        Teams.TeamsList.Add(newTeam);
        //teamsListBox.Items.Add(Teams.TeamsList.Count);
        //teamsListBox.Items.Add(newTeam.ToString());

        end += 4;
        if (end <= Team.Length)
        {
            return end;
        }
        else
        {
            return -1;
        }
    }

When I run this code, "right after response" isn't printing to the UI, whereas the test messages above them are. Also, the emulator will eventually break and throw a FormatException from a line within stringToTeam (which I'll post another question about), which isn't getting called anywhere else. It's also worth mentioning that I have the exact same code for my Bars entity (with the names switched of course), and the bars works perfectly fine. I've compared every line of code in these methods as well as the models and server-side controllers, and they are exactly the same. So why would the bars code work while the teams code doesn't?

If it helps, here's my model code:

public class Teams
{
    private int teamID { get; set; }
    private string teamName { get; set; }
    private string teamCity { get; set; }
    //private object teamFlag { get; set; } //Janci, I was never able to see your comments.  What is teamFlag?  Is that their logo?
    public static List<Teams> TeamsList = new List<Teams>();

    public Teams(int id, string name, string city)
    {
        teamID = id;
        teamName = name;
        teamCity = city;
    }

    public override string ToString()
    {
        return "Team: " + teamID.ToString() + " " + teamName.ToString() + " City: " + teamCity;
    }
}

I have a SQL database hosted on an Azure website and I'm using .NET for my backend. Please help me figure out why my teams code won't work. Thanks.

Answer 1

I think the problem is here:

HttpResponseMessage response = await client.GetAsync("api/bars");

Shouldn't it be:

HttpResponseMessage response = await client.GetAsync("api/teams");

Answer 2

The problem turned out to be that I had the wrong start and end indices in my stringToTeam method. Once I fixed that, the code worked and displayed properly. The method's IndexOf and Substring calls should look like the following:

        start = Team.IndexOf("TeamID", start) + 8;
        int end = Team.IndexOf(",", start); //start index correct
        //teamsListBox.Items.Add(end);
        int id = Convert.ToInt32(Team.Substring(start, end - start)); //throws FormatException for string to DateTime
        //String id = Team.Substring(start, (end - start));
        //teamsListBox.Items.Add("id is " + id);
        start = Team.IndexOf("TeamName", start) + 11;
        end = Team.IndexOf("\"", start);
        //teamsListBox.Items.Add(end);
        String name = Team.Substring(start, (end - start));
        //teamsListBox.Items.Add("name is " + name);
        start = Team.IndexOf("TeamCity", start) + 11;
        end = Team.IndexOf("\"", start);
        String city = Team.Substring(start, (end - start));

After hand-coding my own deserializer and tweaking it for each entity, I discovered the JsonConvert class. I highly recommend against writing your own deserializer. Using JsonConvert, I can delete my stringToTeam() method and replace my old GetTeams() with the following:

public async void GetTeams()
    {
        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://nflff.azurewebsites.net");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            HttpResponseMessage response = await client.GetAsync("api/teams");//not getting past here

            if (response.IsSuccessStatusCode)
            {
                string s = await response.Content.ReadAsStringAsync();
                var deserializedResponse = JsonConvert.DeserializeObject<List<Teams>>(s);
                foreach (Teams team in deserializedResponse)
                {
                    teamsListBox.Items.Add(team.ToString());
                }

            }
            foreach (var team in Teams.TeamsList)
            {
                teamsListBox.Items.Add(team.ToString());
            }
        }
    }

This approach is far less tedious.