JS-Interop : Attempting to use salesforce proxy - dart

Question

I'm trying to use Salesforce's sforce library to place an Ajax call to salesforce. Here is the example javascript that is working:
function setupPage() {
var state = { //state that you need when the callback is called
output : document.getElementById("output"),
startTime : new Date().getTime()};
var callback = {
//call layoutResult if the request is successful
onSuccess: layoutResults,
//call queryFailed if the api request fails
onFailure: queryFailed,
source: state};
sforce.connection.query(
"Select Id, Name, Industry From Account order by Industry",
callback);
}
function queryFailed(error, source) {
// not shown function code
}
function layoutResults(queryResult, source) {
// not shown function code
}
Here's my dart implementation:
import 'dart:html';
import 'package:js/js.dart' as js;
import 'dart:json';
void main() {
js.scoped(() {
var sforce = js.context.sforce;
var callbackSuccess = new js.Callback.once(success);
var callbackFailed = new js.Callback.once(failure);
var sfdc = new js.Proxy(sforce.connection.query("Select Id, Name, Industry From Account order by Industry"),
js.map({"onSuccess" : callbackSuccess, "onFailure" : callbackFailed}));
});
}
void success(queryResult) {
print("queryResult is: " + queryResult);
}
void failure(error) {
print("error is: " + error);
}
The Ajax call is being placed, as I see the POST request being made and returning data. However, I always seem to get this error (and I've tried countless different combinations):
Uncaught TypeError: object is not a function (program):370
construct (program):370
ReceivePortSync.dispatchCall darttest:178
$$._JsSendPortSync.callSync$1 minidartjs:4929
$.Proxy_Proxy$withArgList minidartjs:8194
$.Proxy_Proxy minidartjs:8183
$$.main_anon.call$0 minidartjs:6057
$.scoped minidartjs:8136
$.main minidartjs:8066
$$._IsolateContext.eval$1 minidartjs:276
$.startRootIsolate minidartjs:6533
(anonymous function)
Any help would be greatly appreciated, as I'm not sure where to turn at this point.

Answer 1

You get this error because you try to create a js.Proxy (sfdc) with the result of sforce.connection.query(...) . When you use new js.Proxy(f), f must be a js.Proxy of a js function. Here you get an object and that's why you get the error.
Here's the code that should work.
import 'dart:html';
import 'package:js/js.dart' as js;
import 'dart:json';
void main() {
js.scoped(() {
var sforce = js.context.sforce;
var callbackSuccess = new js.Callback.once(success);
var callbackFailed = new js.Callback.once(failure);
sforce.connection.query("Select Id, Name, Industry From Account order by Industry",
js.map({"onSuccess" : callbackSuccess, "onFailure" : callbackFailed}));
});
}
void success(queryResult, source) {
print("queryResult is: " + queryResult);
}
void failure(error, source) {
print("error is: " + error);
}