I have a multiword String that I'd like to convert to a GET request parameter.
I have an API endpoint /search that takes in the parameter query. Now typically your request would look like http://host/search?query=Hello+World.
I have a String Hello World that I'd like to convert to this URL encoded parameter.
Ofcourse, I could just write the logic to break it into words and add a + in between but I was wondering if the URI class could help with this
I'm using Dart's httpClient to make a request.
Future<String> _getJsonData(String queryToSearch) async {
List data = new List();
var httpClient = new HttpClient();
var request = await httpClient.getUrl(Uri.parse(
config['API_ENDPOINT'] + '/search?query=' +
queryToSearch));
var response = await request.close();
if (response.statusCode == HttpStatus.OK) {
var jsonString = await response.transform(utf8.decoder).join();
data = json.decode(jsonString);
print(data[0]);
return data[0].toString();
} else {
return "{}";
}
}
Essentially, need to encode queryToSearch as the URL parameter.
You can use Uri.http(s) which wrap everythings (query, host, and path) together and encode them accordingly.
final uri = new Uri.http(config['API_ENDPOINT'], '/search', {"query": queryToSearch});
The Uri class provides methods for that
https://api.dartlang.org/stable/1.24.3/dart-core/Uri/encodeQueryComponent.html
https://api.dartlang.org/stable/1.24.3/dart-core/Uri/encodeFull.html
https://api.dartlang.org/stable/1.24.3/dart-core/Uri/encodeComponent.html
You can use Uri.parse(url_string) if you have the full URL in this way.
final String accountEndPoint = 'https://api.npoint.io/2e4ef87d9ewqf01e481e';
Future<Account> getAccountData() async {
try {
final uri = Uri.parse(accountEndPoint); // <===
final response = await http.get(uri);
if (response.statusCode == 200) {
Map<String, dynamic> accountJson = jsonDecode(response.body);
return Future.value(Account.fromJson(accountJson));
} else {
throw Exception('Failed to get account');
}
} catch (e) {
return Future.error(e);
}
}
Related
Future<dynamic> getCoinData() async{
String url = 'https://rest.coinapi.io/v1/exchangerate/BTC/USD?apikey=$apikey';
final parsedUrl = Uri.parse(url);
http.Response response = await http.get(parsedUrl);`enter code here`
if(response.statusCode == 200){
var data = response.body;
var exchangeRate = jsonDecode(data)['rate'];
return exchangeRate;
}else{
print('An error occured, statusCode: ${response.statusCode}');
}
}
I'm trying to get the exchange rate and used it another dart file.
I am using the Flutter Plugin Image_picker to choose images so that I want to upload image after selected the image
Future<File> _imageFile;
void _onImageButtonPressed(ImageSource source) async {
setState(() {
_imageFile = ImagePicker.pickImage(source: source);
});
}
I find this code in flutter documentation but its not work
var uri = Uri.parse("http://pub.dartlang.org/packages/create");
var request = new http.MultipartRequest("POST", url);
request.fields['user'] = 'nweiz#google.com';
request.files.add(new http.MultipartFile.fromFile(
'package',
new File('build/package.tar.gz'),
contentType: new MediaType('application', 'x-tar'));
request.send().then((response) {
if (response.statusCode == 200) print("Uploaded!");
});
Use MultipartRequest class
Upload(File imageFile) async {
var stream = new http.ByteStream(DelegatingStream.typed(imageFile.openRead()));
var length = await imageFile.length();
var uri = Uri.parse(uploadURL);
var request = new http.MultipartRequest("POST", uri);
var multipartFile = new http.MultipartFile('file', stream, length,
filename: basename(imageFile.path));
//contentType: new MediaType('image', 'png'));
request.files.add(multipartFile);
var response = await request.send();
print(response.statusCode);
response.stream.transform(utf8.decoder).listen((value) {
print(value);
});
}
Check this answer
This code works properly.
Used MultipartRequest class
void uploadImage() async {
File _image;
File pickedImage = await ImagePicker.pickImage(source: ImageSource.camera);
setState(() {
_image = pickedImage;
});
// open a byteStream
var stream = new http.ByteStream(DelegatingStream.typed(_image.openRead()));
// get file length
var length = await _image.length();
// string to uri
var uri = Uri.parse("enter here upload URL");
// create multipart request
var request = new http.MultipartRequest("POST", uri);
// if you need more parameters to parse, add those like this. i added "user_id". here this "user_id" is a key of the API request
request.fields["user_id"] = "text";
// multipart that takes file.. here this "image_file" is a key of the API request
var multipartFile = new http.MultipartFile('image_file', stream, length, filename: basename(_image.path));
// add file to multipart
request.files.add(multipartFile);
// send request to upload image
await request.send().then((response) async {
// listen for response
response.stream.transform(utf8.decoder).listen((value) {
print(value);
});
}).catchError((e) {
print(e);
});
}
name spaces:
import 'package:path/path.dart';
import 'package:async/async.dart';
import 'dart:io';
import 'package:http/http.dart' as http;
If you want the uploading function to return the server response, you can use toBytes() instead of transform(), in order to wait until data transmission is complete.
Future<String> upload() async {
String responseString = '';
// Pick image
final image = await ImagePicker().getImage(
source: ImageSource.gallery // or ImageSource.camera
imageQuality: 100,
maxWidth: 1000,
);
// Convert to File
final file = File(image.path);
// Set URI
final uri = Uri.parse('URL');
// Set the name of file parameter
final parameter = 'Name';
// Upload
final request = http.MultipartRequest('POST', uri)
..files.add(await http.MultipartFile.fromPath(parameter, file.path));
final response = await request.send();
if (response.statusCode == 200) {
responseString = String.fromCharCodes(await response.stream.toBytes());
}
return responseString;
}
I am calling an api. I am getting a streamed response after sending the request. But i cannot parse the response and convert it to String/JSON. This is where I am calling the api.
static Future<String> callDeviceListFetchApi() async {
Completer completer = new Completer();
String jsonResponse;
String url = Constants.BASE_URL + Constants.DEVICE_REGISTER_URL;
var client = new http.Client();
var request = new http.Request('GET', Uri.parse(url));
request.headers[HttpHeaders.CONTENT_TYPE] = 'application/json';
request.headers[HttpHeaders.AUTHORIZATION] = '<auth code>';
await client.send(request).then((response) {
response.stream.bytesToString().then((value) {
print(value.toString());
jsonResponse = value.toString();
completer.complete(jsonResponse);
});
}).catchError((error) {
print(error.toString());
});
return completer.future;
}
I am getting the error,
Bad state: Stream has already been listened to Flutter error. Any idea why this is happening?
There's a couple of things wrong with your code. I think you have a slight misunderstanding about how Async and Futures work in dart - you should re-read the docs and this tutorial (part 1 and part 2).
Basically, the problem is that you were returning a 'Future' from an async function. If you return a future from an async function, it has issues (I don't know why the analyzer doesn't catch that).
Future<String> callDeviceListFetchApi() async {
Completer completer = new Completer();
String url = "<url>";
var client = new http.Client();
var request = new http.Request('GET', Uri.parse(url));
request.headers[HttpHeaders.CONTENT_TYPE] = 'application/json';
request.headers[HttpHeaders.AUTHORIZATION] =
'<auth string>';
var response = await client.send(request);
String jsonResponse;
try {
var value = await response.stream.bytesToString();
print(value.toString());
jsonResponse = value.toString();
} catch (error) {
print(error.toString());
}
return completer.complete(jsonResponse);
}
Or not async:
Future<String> callDeviceListFetchApiNotAsync() {
String url = "<url>";
var client = new http.Client();
var request = new http.Request('GET', Uri.parse(url));
request.headers[HttpHeaders.CONTENT_TYPE] = 'application/json';
request.headers[HttpHeaders.AUTHORIZATION] =
'<auth string>';
Completer completer = new Completer();
return client.send(request).then((response) {
return response.stream.bytesToString();
}).then((value) {
print(value.toString());
return value.toString();
}).catchError((error) {
print(error.toString());
// if you use catchError, whatever you return from it
// is the value you'll get wherever you resolve the future.
return null;
});
}
But unless you're trying to do something I'm not seeing, there's a way easier way to do this (assuming all you want to do is get a string from a server):
Future<String> getList() async {
var response = await http.get("<url>", headers: {
HttpHeaders.CONTENT_TYPE: 'application/json',
HttpHeaders.AUTHORIZATION: '<auth string>',
});
if (response.statusCode == 200) {
return response.body;
} else {
throw Error();
}
}
I have two classes, a user_api_manager and a base_api_manager. From user_api_manager i call the get method of base_api_manager which performs an http get request and returns a Future<String>. The getrequest is performed but i am not pass the result to my user_api_manager class. The callback result is always null.
This is my user_api_manager.dart
static Future<Map<String,dynamic>> forgotPasswordAPI(String email) async{
String url = Constants.BASE_URL + Constants.FORGOT_PASSWORD_URL + email;
await BaseApiManager.get(url: url).then((val) {
var response = JSON.decode(val);
var status = response['status'];
String message = '';
print(response);
switch (response['status']) {
case Constants.SUCCESS:
message = Constants.SUCCESS_RESPONSE;
break;
case Constants.SERVER_ERROR:
message = Constants.SERVER_ERROR_MESSAGE;
break;
case Constants.UNAUTHORISED:
message = Constants.UNAUTHORISED_MESSAGE;
break;
}
return {'status':status,'message':message};
});
}
and here is my base_api_manager.dart
static Future<String> get({url : String,
parameters : Map ,
headers: Map }) async {
var client = new http.Client();
Map<String,dynamic> resultJSON;
final c = new Completer();
await client.get(url).then((response) { //response is always null
resultJSON = {
'status' : response.statusCode,
'body' : JSON.decode(response.body)
};
c.complete(resultJSON.toString());
return c.future;
});
}
How to solve this issue?
Move the return c.future outside of the response processing, i.e you want to return this from your get otherwise you will return null.
You can simplify the code. That should make it easier to locate the problem
static Future<String> get({url : String, parameters : Map, headers: Map }) async {
var client = new http.Client();
final response = await client.get(url);
print(response.body);
var resultJSON = {
'status' : response.statusCode,
'body' : JSON.decode(response.body)
};
return resultJSON.toString()
}
What does that code print?
How to ensure UploadStringCompletedEventHandler event has been executed successfully ? in following code you can see i am calling function UploadMyPOST with my lastreads parameter having some data. Now you can see i am saving a variable named response into the MyClassXYZ varialbe. in the extreme last you can see there is a event which invoked by the method UploadMyPost() is filling the server response into the response variable. Now here issue is UploadMyPost(lastreads) executes successfully but its invoked event does not executes. Even cursor do not go on that event by which i am not able to fill server response into the response variable. So Anyone know any approach by which i can wait until that event successfully execute and i could able to save server response ?
private async void MyMethod(MyClassXYZ lastreads)
{
await UploadMyPOST(lastreads);
MyClassXYZ serverResponse = response;
if (serverResponse.Book == null)
{
//Do Something.
}
}
private void UploadMyPOST(MyClassXYZ lastreads)
{
apiData = new MyClassXYZApi()
{
AccessToken = thisApp.currentUser.AccessToken,
Book = lastreads.Book,
Page = lastreads.Page,
Device = lastreads.Device
};
//jsondata is my global variable of MyClassXYZ class.
jsondata = Newtonsoft.Json.JsonConvert.SerializeObject(apiData);
MyClassXYZ responsedData = new MyClassXYZ();
Uri lastread_url = new Uri(string.Format("{0}lastread", url_rootPath));
WebClient wc = new WebClient();
wc.Headers["Content-Type"] = "application/json;charset=utf-8";
wc.UploadStringCompleted += new UploadStringCompletedEventHandler(MyUploadStringCompleted);
wc.UploadStringAsync(lastread_url, "POST", jsondata);
}
private void MyUploadStringCompleted(object sender, UploadStringCompletedEventArgs e)
{
try
{
if (e.Error == null)
{
string resutls = e.Result;
DataContractJsonSerializer json = new DataContractJsonSerializer(typeof(MyClassXYZ));
MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(resutls));
response = (MyClassXYZ)json.ReadObject(ms);
}
else
{
string sx = e.Error.ToString();
}
}
catch(Exception exe)
{
}
}
//After Stephen suggession i used the HttpClient so i have written new code with the help of HttpClient. Code is building successfully but at run time cursor goes out from this method to the parent method where from its calling.
private async Task<string> UploadMyPOST(MyClassXYZ lastreads)
{
string value = "";
try
{
apiData = new LastReadAPI()
{
AccessToken = thisApp.currentUser.AccessToken,
Book = lastreads.Book,
Page = lastreads.Page,
Device = lastreads.Device
};
jsondata = Newtonsoft.Json.JsonConvert.SerializeObject(apiData);
LastRead responsedData = new LastRead();
Uri lastread_url = new Uri(string.Format("{0}lastread", url_rootPath));
HttpClient hc = new HttpClient();
//After following line cursor go back to main Method.
var res = await hc.PostAsync(lastread_url, new StringContent(jsondata));
res.EnsureSuccessStatusCode();
Stream content = await res.Content.ReadAsStreamAsync();
return await Task.Run(() => Newtonsoft.Json.JsonConvert.SerializeObject(content));
value = "kd";
}
catch
{ }
return value;
}
I recommend that you use HttpClient or wrap the UploadStringAsync/UploadStringCompleted pair into a Task-based method. Then you can use await like you want to in MyMethod.
Thank you Stephen Clear you leaded me in a right direction and i did POST my request successfully using HttpClient.
HttpClient hc = new HttpClient();
hc.BaseAddress = new Uri(annotation_url.ToString());
HttpRequestMessage req = new HttpRequestMessage(HttpMethod.Post, myUrl);
HttpContent myContent = req.Content = new StringContent(myJsonData, Encoding.UTF8, "application/json");
var response = await hc.PostAsync(myUrl, myContent);
//Following line for pull out the value of content key value which has the actual resposne.
string resutlContetnt = response.Content.ReadAsStringAsync().Result;
DataContractJsonSerializer deserializer_Json = new DataContractJsonSerializer(typeof(MyWrapperClass));
MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(resutlContetnt.ToString()));
AnnotateResponse = deserializer_Json.ReadObject(ms) as Annotation;