return datacontext.fetchEntity('Hearing', vm.hearingID()).then(function (result) {
vm.hearingEntity = result.entity;
vm.hearingEntity.entityAspect.loadNavigationProperty("Client");
});
What can be the reason behind "Client" navigation property returned as null in the above code ?
"loadNavigationProperty" is an asynchronous method that returns a promise. You need to wait for the promise to return. Something like:
vm.hearingEntity.entityAspect.loadNavigationProperty("Client").then(function(data) {
// this is your result.
var clients = data.results;
});
Related
I am trying to pass messages between content script and the extension
Here is what I have in content-script
chrome.runtime.sendMessage({type: "getUrls"}, function(response) {
console.log(response)
});
And in the background script I have
chrome.runtime.onMessage.addListener(
function(request, sender, sendResponse) {
if (request.type == "getUrls"){
getUrls(request, sender, sendResponse)
}
});
function getUrls(request, sender, sendResponse){
var resp = sendResponse;
$.ajax({
url: "http://localhost:3000/urls",
method: 'GET',
success: function(d){
resp({urls: d})
}
});
}
Now if I send the response before the ajax call in the getUrls function, the response is sent successfully, but in the success method of the ajax call when I send the response it doesn't send it, when I go into debugging I can see that the port is null inside the code for sendResponse function.
From the documentation for chrome.runtime.onMessage.addListener:
This function becomes invalid when the event listener returns, unless you return true from the event listener to indicate you wish to send a response asynchronously (this will keep the message channel open to the other end until sendResponse is called).
So you just need to add return true; after the call to getUrls to indicate that you'll call the response function asynchronously.
The accepted answer is correct, I just wanted to add sample code that simplifies this.
The problem is that the API (in my view) is not well designed because it forces us developers to know if a particular message will be handled async or not. If you handle many different messages this becomes an impossible task because you never know if deep down some function a passed-in sendResponse will be called async or not.
Consider this:
chrome.extension.onMessage.addListener(function (request, sender, sendResponseParam) {
if (request.method == "method1") {
handleMethod1(sendResponse);
}
How can I know if deep down handleMethod1 the call will be async or not? How can someone that modifies handleMethod1 knows that it will break a caller by introducing something async?
My solution is this:
chrome.extension.onMessage.addListener(function (request, sender, sendResponseParam) {
var responseStatus = { bCalled: false };
function sendResponse(obj) { //dummy wrapper to deal with exceptions and detect async
try {
sendResponseParam(obj);
} catch (e) {
//error handling
}
responseStatus.bCalled= true;
}
if (request.method == "method1") {
handleMethod1(sendResponse);
}
else if (request.method == "method2") {
handleMethod2(sendResponse);
}
...
if (!responseStatus.bCalled) { //if its set, the call wasn't async, else it is.
return true;
}
});
This automatically handles the return value, regardless of how you choose to handle the message. Note that this assumes that you never forget to call the response function. Also note that chromium could have automated this for us, I don't see why they didn't.
You can use my library https://github.com/lawlietmester/webextension to make this work in both Chrome and FF with Firefox way without callbacks.
Your code will look like:
Browser.runtime.onMessage.addListener( request => new Promise( resolve => {
if( !request || typeof request !== 'object' || request.type !== "getUrls" ) return;
$.ajax({
'url': "http://localhost:3000/urls",
'method': 'GET'
}).then( urls => { resolve({ urls }); });
}) );
I use my postgres database query to determine my next action. And I need to wait for the results before I can execute the next line of code. Now my conn.query returns a Future but I can't manage to get it async when I place my code in another function.
main() {
// get the database connection string from the settings.ini in the project root folder
db = getdb();
geturl().then((String url) => print(url));
}
Future geturl() {
connect(db).then((conn) {
conn.query("select trim(url) from crawler.crawls where content IS NULL").toList()
.then((result) { return result[0].toString(); })
.catchError((err) => print('Query error: $err'))
.whenComplete(() {
conn.close();
});
});
}
I just want geturl() to wait for the returned value but whatever I do; it fires immediately. Can anyone point me a of a piece of the docs that explains what I am missing here?
You're not actually returning a Future in geturl currently. You have to actually return the Futures that you use:
Future geturl() {
return connect(db).then((conn) {
return conn.query("select trim(url) from crawler.crawls where content IS NULL").toList()
.then((result) { return result[0].toString(); })
.catchError((err) => print('Query error: $err'))
.whenComplete(() {
conn.close();
});
});
}
To elaborate on John's comment, here's how you'd implement this using async/await. (The async/await feature was added in Dart 1.9)
main() async {
try {
var url = await getUrl();
print(url);
} on Exception catch (ex) {
print('Query error: $ex');
}
}
Future getUrl() async {
// get the database connection string from the settings.ini in the project root folder
db = getdb();
var conn = await connect(db);
try {
var sql = "select trim(url) from crawler.crawls where content IS NULL";
var result = await conn.query(sql).toList();
return result[0].toString();
} finally {
conn.close();
}
}
I prefer, in scenarios with multiple-chained futures (hopefully soon a thing of the past once await comes out), to use a Completer. It works like this:
Future geturl() {
final c = new Completer(); // declare a completer.
connect(db).then((conn) {
conn.query("select trim(url) from crawler.crawls where content IS NULL").toList()
.then((result) {
c.complete(result[0].toString()); // use the completer to return the result instead
})
.catchError((err) => print('Query error: $err'))
.whenComplete(() {
conn.close();
});
});
return c.future; // return the future to the completer instead
}
To answer your 'where are the docs' question: https://www.dartlang.org/docs/tutorials/futures/
You said that you were trying to get your geturl() function to 'wait for the returned value'. A function that returns a Future (as in the example in the previous answer) will execute and return immediately, it will not wait. In fact that is precisely what Futures are for, to avoid code doing nothing or 'blocking' while waiting for data to arrive or an external process to finish.
The key thing to understand is that when the interpreter gets to a call to then() or 'catchError()' on a Future, it does not execute the code inside, it puts it aside to be executed later when the future 'completes', and then just keeps right on executing any following code.
In other words, when using Futures in Dart you are setting up chunks of code that will be executed non-linearly.
In the below cloud code i would like to get a feedback of the saveAll function but after calling the code from my client in the parse Logs page i can only see:
I2014-10-08T15:28:32.930Z] v249: Ran cloud function acceptMeetingBis for user dyGu143Xho with:
Input: {"meetingId":"bUSTGNhOer"}
Result: Meeting accepted
Here is my cloud code:
Parse.Cloud.define("acceptMeetingBis", function(request, response) {
var userAcceptingTheMeeting = request.user;
var meetingId = request.params.meetingId;
var changedObjects = [];
var queryForMeeting = new Parse.Query("MeetingObject");
queryForMeeting.equalTo("objectId", meetingId);
queryForMeeting.first({
success: function(meeting) {
var userCreatorOfMeeting = meeting.get("user");
userAcceptingTheMeeting.increment("acceptedMeetings", +1);
changedObjects.push(userAcceptingTheMeeting);
meeting.add("participantsObjectId", userAcceptingTheMeeting.id);
if (meeting.get("participantsObjectId").length === meeting.get("meetingNumberOfPersons")) {
meeting.set("isAvailable", false);
}
changedObjects.push(meeting);
Parse.Object.saveAll(changedObjects, {
success: function(objects) {
console.log("Successfully saved objects"); //this line doesn't show up
response.success("objects saved");
},
error: function(error) {
// An error occurred while saving one of the objects.
response.error(error);
}
});
//future query and push notifications will go here
response.success("Meeting accepted");
},
error: function() {
response.error("Failed to accept the meeting");
}
});
});
I will also need to add some push and another nested query after the saveAll() but before doing/trying that i would like to know if this is the right method to use or if i have to build the code in a different way. I'm new to javascript and honestly i'm struggling to understand some concepts, like promises. Any help would be much appreciated.
Your call to
Parse.Object.saveAll
is asynchronous, and you call
response.success("Meeting accepted")
immediately after making the asynchronous call, which ends the cloud code running of the method. If you simply replace the
response.success("objects saved")
with
response.success("Meeting accepted")
you should get what you want.
I didn't see the rest of your question about promises. You should check out Parse's documentation on chaining promises, which is what you want here.
Essentially, here's what you'll want to do:
Parse.Cloud.define("acceptMeetingBis", function(request, response) {
var userAcceptingTheMeeting = request.user;
var meetingId = request.params.meetingId;
var changedObjects = [];
var meetingToAccept;
var queryForMeeting = new Parse.Query("MeetingObject");
queryForMeeting.get(meetingId).then(function(meeting) {
meetingToAccept = meeting;
var userCreatorOfMeeting = meeting.get("user");
userAcceptingTheMeeting.increment("acceptedMeetings", +1);
return userAcceptingTheMeeting.save();
}).then(function(userWhoAcceptedMeetingNowSaved) {
meetingToAccept.add("participantsObjectId", userWhoAcceptedMeetingNowSaved.id);
if (meetingToAccept.get("participantsObjectId").length === meetingToAccept.get("meetingNumberOfPersons")) {
meetingToAccept.set("isAvailable", false);
}
return meetingToAccept.save();
}).then(function(savedMeeting) {
response.success("Meeting accepted");
}, function(error) {
response.error("Failed to accept the meeting");
});
});
For each asynchronous action you want to do, perform it at the end of one of the .then functions and return the result (it returns a promise). Keep adding .then functions until you're done all the work you want to do, at which point call response.success.
I´v got a "detail" view and a controller that initilizes data with an id.
My view:
<div ng-app="AFApp" ng-controller="AgentCtrl" ng-init="init('#Model.Id')">
My controller:
$scope.id;
$scope.agent = {};
$scope.init = function (id) {
$scope.id = id;
getAgent();
getAgentStatus();
getSystemInfo();
getActions();
};
The problem is that the method "getAgentStatus();" gets executed before "getAgent();". The "getAgentStatus" needs the $scope.agent data that "getAgent" provides. The function getAgentStatus has an attached timer, and it gets the value as the timer elepses but not in the init function. Can someone please help me out with the method execution sequence in angular controllers and how the id parameter is provided the best possible way.
See methods below:
function getAgent() {
agentDataFactory.getAgent($scope.id)
.success(function (data) {
$scope.agent = data;
})
.error(function (error) {
console.log('Unable to load data: ' + error.message);
});
};
function getAgentStatus() {
if (typeof ($scope.agent.ServiceUrl) == 'undefined' || $scope.agent.ServiceUrl == null) {
console.log('getAgentStatus: ServiceUrl is undefined ' + JSON.stringify($scope.agent));
}
agentDataFactory.getAgentStatus($scope.agent.ServiceUrl)
.success(function (data) {
$scope.agent.CurrentStatus = data.Status;
$scope.agent.CurrentInterval = data.Interval;
})
.error(function (error) {
console.log('Unable to load data: ' + error);
});
$timeout(getAgentStatus, 3000);
};
You can pass getAgentStatus() as a callback parameter to getAgent() and have it executed in the success callback (at which point agent will be defined):
function getAgent(callback) {
agentDataFactory.getAgent($scope.id)
.success(function (data) {
$scope.agent = data;
callback && callback();
})
.error(function (error) {
console.log('Unable to load data: ' + error.message);
});
};
$scope.init = function (id) {
$scope.id = id;
getAgent(getAgentStatus);
getSystemInfo();
getActions();
};
Short explanation:
Some highlights first:
agentDataFactory.getAgent($scope.id).success(...).error(...);:
Creates a promise (which will be resolved) asynchronously and registers two callbacks, one if the promise is successfully resolved and one for the case of an error.
.success(function (data) { $scope.agent = data; }):
Registers a callbackfor when the promise is successfully resolved. When (and if) that happens, $scope.agent will be set.
function getAgentStatus() { if (typeof ($scope.agent.ServiceUrl...:
Tries to access some properties of $scope.agent and thus requires the object to be defined.
So, what happens with your code:
getAgent() is gets called.
[$scope.agent is undefined]
A promise is created that when resolved will set $scope.agent.
[$scope.agent is undefined]
getAgent() returns and getAgentStatus() is called.
[$scope.agent is undefined]
getAgentStatus() tries to access $scope.agent's properties and fails.
[$scope.agent is undefined]
The promise created in step 2 is resolved and its success callback get executed.
[$scope.agent is finally defined]
My version of the code ensures that getAgentStatus() is not executed before the promise is resolved and thus $scope.agent is defined:
getAgent() is gets called.
[$scope.agent is undefined]
A promise is created that when resolved will set $scope.agent.
[$scope.agent is undefined]
getAgent() returns and other functions get called (e.g. getSystemInfo(), getActions(), etc.).
[$scope.agent is undefined]
The promise created in step 2 is resolved and its success callback get executed.
[$scope.agent is finally defined]
Only now does getAgentStatus() get called and it works as expected since...
[$scope.agent is defined]
Take a look at the $q service for more info on Angular promises.
var display_message="";
$('input:checked').each(function(index) {
var profile_id=$(this).val();
$.ajax({
type: 'post',
url: 'myUrl',
data: data,
success: function(data) {
if(data=="ok")
display_message = display_message + data +", ";
}
});
});
alert(display_message);
alert(display_message);
if($.trim(display_message)!=""){
jAlert("Your birthdate already exits in "+display_message.substring(0, display_message.length - 2)+".", "Bdate");
return false;
}
in this code, i use two alert-box for display display_message variable value.
when i run successfully this code, in 1st alert-box i get blank value and second alert-box i get value which i needed, then it will go in if condition.
if i doesn't use alert box then it will always take null value in display_message variable and never enters into the if condition. so what i need to change to run this code without alert box?
You are making an asynchronous call via AJAX, but your code is executing synchronously. So it is returning before the AJAX call completes. The first alert box just gives the function time to catch up. You need to handle all this code in your success callback.
var display_message="";
$('input:checked').each(function(index) {
var profile_id=$(this).val();
$.ajax({
type: 'post',
url: 'myUrl',
data: data,
success: function(data) {
if(data=="ok")
display_message = display_message + data +", ";
if($.trim(display_message)!=""){
jAlert("Your birthdate already exits in "+display_message.substring(0, display_message.length - 2)+".", "Bdate");
return false;
}
});
});
You want all your ajax queries to finish and return results, right?
Then this is a synchronization problem.
I would suggest this approach (code is simplified for clarity).
var inputs_processed = -1;
var inputs_to_process = -1;
function queryData() {
inputs_to_process = $('input:checked').length;
$('input:checked').each(function() {
$.ajax({success: function(data) {
inputs_processed += 1;
// build up that message
}});
});
}
function displayResult() {
if (inputs_processed == inputs_to_process) {
// display result
} else {
// not all queries finished yet. Wait.
setTimeout(displayResult, 500);
}
}
queryData();
displayResult();
Basically, you know how many requests should be made and you don't display result until that number of requests returns.
Why your data is "data"? I cant see any variable called data is declared here. You should pass in the value you want to use as the parameter into the data options.
Edit: This is why u getting the null value. data is not initialize into anything. Only after the success function, your "data" will have the value since you declare the return value with the same name