Post a list and iterate it using Dart - json

Question

I'm trying to post some data from a dart project to another and store them in a mongoDB
Post code:
import 'dart:io';
void main() {
List example = [
{"source": "today", "target": "tomorrow"},
{"source": "yesterday", "target": "tomorrow"},
{"source": "today", "target": "yesterday"}
];
new HttpClient().post('localhost', 4040, '')
.then((HttpClientRequest request) {
request.headers.contentType = ContentType.JSON;
request.write(example);
return request.close();
});
}
Code that receives it, inside another file
void start() {
HttpServer.bind(address, port)
.then((HttpServer server) {
// Log in console to show that server is listening
print('Server listening on ${address}:${server.port}');
server.listen((HttpRequest request) {
request.transform(UTF8.decoder).listen(sendToDatastore);
});
});
}
void sendToDatastore(String contents) {
var dbproxy = new dbProxy("myDb");
dbproxy.write("rawdata", contents);
index++;
// non related to the problem code
}
bool write(collectionName, document)
{
Db connection = connect();
DbCollection collection = connection.collection(collectionName);
connection.open().then((_){
print('writing $document to db');
collection.insert(document);
}).then((_) {
print('closing db');
connection.close();
});
return true;
}
What I'm struggling with is that I'm using
request.transform(UTF8.decoder).listen(sendToDatastore);
so I'm converting the request stream to a string as I couldn't find the way to send it as Json.
And then in sendToDatastore I'm not able to parse it properly in order to store it. As far as I understand I'd need to get every Json object as a Map to store it as I'm getting this error
Uncaught Error: type 'String' is not a subtype of type 'Map' of 'document'.
Thanks,
UPDATE
If I try to do something like this in sendToDatastore
void sendToDatastore(String contents) {
var dbproxy = new dbProxy("myDb");
var contentToPass = JSON.decode(contents);
contentToPass.forEach((element) => dbproxy.write("rawdata", element));
index++;
// non related to the problem code
}
It raises this error
Uncaught Error: FormatException: Unexpected character (at character 3)
[{source: today, target: tomorrow}, {source: yesterday, target: tomorrow}, ...
^
In the use of JSON.decode
UPDATE2
The error was that I wasn't sending actual Json from the "post code". I used
// ...
request.write(JSON.encode(example));
// ...
and everything worked fine
Thanks

Answer 1

You should be able to use the dart:convert package.
You can then use:
String str = JSON.encode(obj)
and
var obj = JSON.decode(str)
to convert string/json.