Pfthb

The class Requests set up an HttpClientRequest. The method getTeamsJsonForRequest is supposed to return the JSON response. However, the variable 'return' is not being assigned properly I assum. The print 'CONTS' in the .then response successfully prints the correct response, but printing 'myres' sections says result is null. Not sure why result is not being assigned in the response.transform section.

class Requests 
 static Future getTeamsJsonForRequest(String reqPath) async
 var result;
 HttpClient myhttp = new HttpClient();
 String path = '/api/v3' + reqPath;
 myhttp.get('www.thebluealliance.com', 80, path) 
 .then((HttpClientRequest request) 
 request.headers.set("accept", "application/json");
 request.headers.set("X-TBA-Auth-Key", "XXXXX");
 return request.close();
 )
 .then((HttpClientResponse response) 
 response.transform(utf8.decoder).transform(json.decoder).listen((conts) 
 print('CONTS: ' + conts.toString());
 result = json.decode(conts).toString();
 );
 );
 print('myres: ' + result.toString());
 return result;
 
 

Short answer: avoid using Future.then inside an async method.

Your print is executing before the response comes back. https://www.dartlang.org/tutorials/language/futures#async-await

Without an await any work that is done asynchronously will happen after subsequent statements in this function are executed.

Here is how I'd write this:

Future<String> teamsJsonForRequest(String requestPath) async 
 var client = new HttpClient();
 var path = '/api/v3$requestPath';
 var request = (await client.get('www.thebluealliance.com', 80, path))
 ..headers.set("accept", "application/json")
 ..headers.set("X-TBA-Auth-Key", "XXXXX");
 var response = await request.close();
 var result =
 await response.transform(utf8.decoder).transform(json.decoder).single;
 print('myres: $result');
 return result;

In

 .then((HttpClientResponse response) 
 response.transform(utf8.decoder).transform(json.decoder).listen((conts) 
 print('CONTS: ' + conts.toString());
 result = json.decode(conts).toString();
 );
 );
 print('myres: ' + result.toString());
 return result;

this line

result = json.decode(conts).toString();

is executed muuuch later than this line

return result;

The request to the server is sent and then return result; is executed.
The then(...) part is executed when the response from the server arrives.

Change the code to

class Requests 
 static Future getTeamsJsonForRequest(String reqPath) async
 HttpClient myhttp = new HttpClient();
 String path = '/api/v3' + reqPath;
 return myhttp.get('www.thebluealliance.com', 80, path) 
 .then((HttpClientRequest request) 
 request.headers.set("accept", "application/json");
 request.headers.set("X-TBA-Auth-Key", "XXXXX");
 return request.close();
 )
 .then((HttpClientResponse response) 
 response.transform(utf8.decoder).transform(json.decoder).listen((conts) 
 print('CONTS: ' + conts.toString());
 var result = json.decode(conts).toString();
 print('myres: ' + result.toString());
 return result;
 );
 );