/// <summary>
/// Run a query against Nebulon ON
/// </summary>
/// <typeparam name="T">The Type of the target array</typeparam>
/// <param name="name">Name of the query</param>
/// <param name="parameters">Parameters for the query</param>
/// <returns>List of items returned by the query</returns>
public T[] RunQueryMany <T>(string name, GraphQLParameters parameters = null) where T : new()
{
try
{
// field types for objects are all marked with a property attribute
// for all supported Neb* types. Every field that should be queried for
// must be provided in the class properties as JsonPath attribute.
string[] fields = GetQueryFields(typeof(T));
// this composes a new GraphQL method of type query.
GraphQLMethod method = new GraphQLMethod(
GraphQLMethodType.Query,
name,
parameters,
fields
);
// run the task
object[] taskResults = Run <T>(method);
// this is the most tricky part here as the type conversion from a generic
// type to something else doesn't seem to be very reliable. However,
// this approach seeps to work fine (according to Stack Overflow).
return(CastObjects <T>(taskResults));
}
catch (AggregateException errors)
{
string errorMessage = "Error executing query";
foreach (Exception err in errors.InnerExceptions)
{
errorMessage = string.Concat(errorMessage, ", ", err.Message);
}
Logger.WriteError(errorMessage);
throw new Exception(errorMessage);
}
catch (TimeoutException err)
{
Logger.WriteError(err.Message);
throw new Exception(err.Message);
}
catch (Exception err)
{
Logger.WriteError(err.Message);
throw new Exception(err.Message);
}
}
/// <summary>
/// Execute a GraphQL method against nebulon on.
/// </summary>
/// <typeparam name="T">Type of the object that we expect as a response</typeparam>
/// <param name="method">GraphQL method</param>
/// <returns></returns>
private object[] Run <T>(GraphQLMethod method) where T : new()
{
// this could be made static as this URI should never really change.
// the server doesn't end in a "/", but I think we should eventually
// check for a malformed server.
string uri = string.Concat(this._server, "/query");
Logger.WriteDebug(string.Format(
"Sending '{0}' to {1}.",
method,
uri
));
// prepare the request body. We need to make a JSON body
// for UCPAI using JSON object with a single property "query".
JObject jsonObject = new JObject(new JProperty(@"query", method.ToString()));
string bodyString = JsonConvert.SerializeObject(jsonObject, Formatting.Indented);
// we want to keep track of how long this request took, so we keep track
// of the start time. If we later don't care about it anymore, we can
// delete this.
DateTime start = DateTime.UtcNow;
HttpContent content = new StringContent(
bodyString,
Encoding.UTF8,
@"application/json"
);
content.Headers.Add("Nebulon-Client-App", _assemblyVersion);
content.Headers.Add("Nebulon-Client-Platform", _platform);
HttpResponseMessage response = Post(uri, content);
string responseString = ReadResponseBodyString(response);
// this is the earliest we should stop recording the time / duration of the
// request as this is mostly now on the client side, not the server.
double durationMs = (DateTime.UtcNow - start).TotalMilliseconds;
Logger.WriteDebug(string.Format("Got response '{0}' in {1} ms.",
response.StatusCode,
durationMs));
Logger.WriteDebug(string.Concat("Response:", responseString));
// the UCAPI server response with JSON formatted data
// with a well known structure. one property is "errors" and is
// present when the request failed, and another property "data"
// which is populated when the request succeeds.
JObject json = JObject.Parse(responseString);
// check for errors (any HTTP code outside of 2xx). We probably want to still
// get the response body and bubble that up in the exception
int statusCode = (int)response.StatusCode;
if (200 < statusCode || statusCode >= 300 || json.ContainsKey("errors"))
{
string errorMessage = string.Format("Request error (HTTP {0})",
statusCode);
if (json.ContainsKey("errors"))
{
// get the errors that are specified in the response JSON
// and add them to the error string.
IEnumerable <JToken> errors = json.SelectTokens("errors[*].message", true);
foreach (JToken error in errors)
{
// convert the JToken to a string and append it to the
// error message
string errorString = (string)error.ToObject(typeof(string));
errorMessage = string.Concat(errorMessage, ", ", errorString);
}
}
throw new Exception(errorMessage);
}
// read data. This query could fail when the data is not present in the
// response. So, we're checking for the value to not be null.
string jsonPathData = string.Concat("$.data.", method.MethodName);
JToken data = json.SelectToken(jsonPathData, false);
if (data == null)
{
return(null);
}
if (data.Type != JTokenType.Array)
{
if (data.Type == JTokenType.Object)
{
JObject resultData = data.Value <JObject>();
return(new object[] { ObjectFromJObject(resultData, typeof(T)) });
}
// Convert primitive types directly
return(new object[] { data.Value <T>() });
}
JArray dataArray = data.Value <JArray>();
List <object> resultDataArray = new List <object>();
foreach (JObject item in dataArray)
{
resultDataArray.Add(ObjectFromJObject(item, typeof(T)));
}
return(resultDataArray.ToArray());
}
