c＃HttpWebRequest 404，对象不完整列表返回null

Question

I have a code that retrieves Json value from a Api link. This is deserialized and stored as object in a list. The ID values in this list are then used to retrieve other Json values from a different Api link. Only these Id's have a possibility to not exist in the second Api link. If this is the case all that is shown is {"text":"no such id"} and the program crashes with a 404 error.

This is the code:

public RootObject objFromApi_idExistListings(string url)
        {

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

            try
            {
                WebResponse response = request.GetResponse();
                using (Stream responseStream = response.GetResponseStream())
                {
                    StreamReader reader = new StreamReader(responseStream, Encoding.UTF8);
                    var jsonReader = new JsonTextReader(reader);
                    var serializer = new JsonSerializer();
                    return serializer.Deserialize<RootObject>(jsonReader);
                }
            }
            catch (WebException)
            {
                return null;
            }
        }

When a 404 is hit it returns everything null from there on. Not only that single Api request and then continues, no the entire list is then returned null.

How do i get around to only make that object return null and everything else continues. Or how do i skip the entire making of that object when its a 404, doesnt have to be returned null as long as the code can continue going and deserialize all left Api links it has to work through.

Answer 1

You could use something like this to bail out if there is a 404 response (or any response other than 200).

try
{
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    if (response.StatusCode != System.Net.HttpStatusCode.OK) return null;
    //Continue by getting and parsing the response stream