Develop Reference

Dotmim.Sync null reference exception in web proxy post method

I am using Dotmim.sync framework. I am trying to sync an mssql database with my xamarin android app's sqlite database. So I implemented the web proxy to reach the database from the android app.
The proxy starts fine, but then when I call the sync from the android app the Post method gives a null reference error, but I cannot find what is null.
In the ASP.NET Core web app's Startup file:
public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews();
// [Required]: To be able to handle multiple sessions
services.AddMemoryCache();
// [Required]: Get a connection string to your server data source
var connectionString = #"[my connection string]";
// [Required]: Tables list involved in the sync process
var tables = new string[] { "dbo.Album", "dbo.Artist", "dbo.Customer", "dbo.Invoice", "dbo.InvoiceItem", "dbo.Track" };
// [Required]: Add a SqlSyncProvider acting as the server hub.
services.AddSyncServer<SqlSyncChangeTrackingProvider>(connectionString, tables);
}
The SyncController:
[ApiController]
[Route("api/[controller]")]
public class SyncController : ControllerBase
{
private WebServerManager manager;
public SyncController(WebServerManager man) => this.manager = man;
[HttpPost]
public async Task Post()
{
await manager.HandleRequestAsync(this.HttpContext);
} //----> the Null error comes
[HttpGet]
public async Task Get() => await manager.HandleRequestAsync(this.HttpContext);
}
In the android app the sync function that is called:
public async Task SyncDatabase(string connString, Context context)
{
var handler = HttpClientHandlerService.GetInsecureHandler();
HttpClient httpClient = new HttpClient(handler);
httpClient.DefaultRequestHeaders.Host = $"localhost:44372";
var serverOrchestrator = new WebClientOrchestrator("https://10.0.2.2:44372/api/sync", client: httpClient);
// Second provider is using plain sqlite provider
var clientProvider = new SqliteSyncProvider(connString);
var agent = new SyncAgent(clientProvider, serverOrchestrator);
try
{
var result = await agent.SynchronizeAsync(); //---> error comes when this line is called
var output = result.ToString();
output = output.Replace("\n", " ").Replace("\t", " ").Replace("\r", " ");
Toast.MakeText(context, output, ToastLength.Long).Show();
}
catch (Exception e)
{
Toast.MakeText(context, e.Message, ToastLength.Long).Show();
}
}
Let me know what further information should I supply to solve this.
EDIT:
Calling from postman it gives this error: {"tn":"HttpHeaderMissingExceptiopn","m":"Header dotmim-sync-scope-name is missing."}
EDIT2:
Server orchestrator on the client side:
On the server side:
The details of the exception:

SOLUTION:
I tried the sync with a different database and tables, and that worked, so it was clear that dotmim has some problem with the tables I was using. So after lot of thinking I tried with a different schema name instead of dbo, since the other database that worked had something else. And it turns out the sync has some problem if the schema name is dbo, something gets mixed probably when it tries to create its own new tables. So use something different from dbo for schema.

UnityWebRequest does nothing on IL2CPP Build

I've been trying to simply call an api on an android build supporting 64 bit (IL2CPP build) and the UnityWebRequest class didnt seem to work. It's being called via a simple ui button click. It hits the webRequest.SendWebRequest(); and nothing happens. Ive tried the following samples. One, directly from the Unity docs for UnityWebRequest and others using standard HttpClient.
UnityWebRequest:
IEnumerator GetRequest(string uri)
{
using (UnityWebRequest webRequest = UnityWebRequest.Get(uri))
{
webRequest.SetRequestHeader("Authorization", "Bearer " + API_KEY);
yield return webRequest.SendWebRequest();
if (webRequest.isNetworkError)
{
debugText.text = ": Error: " + webRequest.error;
coroutineAllowed = false;
}
else
{
debugText.text = ":\nReceived: " + webRequest.downloadHandler.text;
dynamic jsonObj = JsonConvert.DeserializeObject(webRequest.downloadHandler.text);
foreach (var obj in jsonObj["businesses"])
{
businessResults.Add(new Business()
{
name = (string)obj["name"],
image_url = (string)obj["image_url"],
review_count = (string)obj["review_count"],
rating = (string)obj["rating"],
Coordinates = new Coordinates()
{
Latitude = (float)obj["coordinates"]["latitude"],
Longitude = (float)obj["coordinates"]["longitude"]
},
price = (string)obj["price"]
});
}
debugText.text = businessResults.Count.ToString();
//coroutineAllowed = true;
}
debugText.text = "getRequest 4";
}
}
This unfortunately did nothing at the yield return webRequest.SendWebRequest();
The next sample I tried was using HttpClient():
IEnumerator HttpClientCall(string uri) //possibly wrap in IEnumerator
{
debugText.text += "http coroutine started" +Environment.NewLine;
using (var httpClient = new HttpClient())
{
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", API_KEY);
var response = httpClient.GetAsync(uri);
if (response.Result.StatusCode != HttpStatusCode.OK)
{
debugText.text += "FAILED HTTP GET";
}
yield return response.Result.Content.ReadAsStringAsync();
dynamic jsonObj = JsonConvert.DeserializeObject(response.Result.Content.ReadAsStringAsync().Result);
foreach (var obj in jsonObj["businesses"])
{
businessResults.Add(new Business()
{
name = (string)obj["name"],
image_url = (string)obj["image_url"],
review_count = (string)obj["review_count"],
rating = (string)obj["rating"],
Coordinates = new Coordinates()
{
Latitude = (float)obj["coordinates"]["latitude"],
Longitude = (float)obj["coordinates"]["longitude"]
},
price = (string)obj["price"]
});
debugText.text += Environment.NewLine + ((string)obj["name"]);
}
}
}
Once again, nothing when it hits yield return response.Result.Content.ReadAsStringAsync();
These all work on PC, and they both return results that i'm expecting.
The next thing i heard was about setting the android manifest application tag with android:usesCleartextTraffic="true"
This unfortunately, also did nothing for me lol. I know it has to be the 64 support, because this works on a standard build. The moment i go to build with 64 support, it doesnt work.
Any help on why it's not returning appropriately would be very helpful.
side note, i know the code is pretty ugly, but after i can figure out why the build doesnt work on the device a heavy refactoring is going to be in play. Thanks in advance!

So after a lot of trouble shooting ive found out why this was not working. The main issue seems to be stemming from my use of the standard Newtonsoft Json package when Unity, apparently, has their own internal JsonUtility class. After changing this:
dynamic jsonObj = JsonConvert.DeserializeObject(response.Result.Content.ReadAsStringAsync().Result);
To This:
var js = JsonUtility.FromJson<T>(response.Result.Content.ReadAsStringAsync().Result);
my results are finally showing in the the apk build correctly.
Also, to note that to map correctly, the JsonUtility.FromJson must be typed to a class that exactly mirrors the incoming json object explicitly.
The page article that finally helped me with this issue is here.
P.S.
Thank you to #RetiredNinja for trying to help instead of just downvoting and saying nothing of value. You're amazing!

HTTP POST request from app works on iPhone but not on Android phone

In my ionic app I have a POST request to do login. This works fine on an iPhone but when I test the app on an Android phone the server returns a 404 Not Found error.
My code for making the HTTP request looks like this:
loginUser: function(email,password) {
var em = email.replace(/\s/g,'');
var pw = password.replace(/\s/g,'');
var url = apiDomain + '/api/v1/user/login/';
if (em && pw) {
return $http.post(url, {
auth: {
email: em,
password: pw
}
}).then(function successCallback(response) {
alert('login success. response = '+JSON.stringify(response));
return response;
}, function errorCallback(response) {
alert('login fail. response = '+JSON.stringify(response));
return -1;
});
}
},
Can anyone think of a reason why this would work on an iPhone but not on an Android phone?
The text shown by the alert() in the errorCallback is:
login fail. response = {
"data":"",
"status":404,
"config":{
"method":"POST",
"transformRequest":[null],
"url":"http://cues-server-dev.elasticbeanstalk.com/api/v1/user/login/",
"data":{
"auth":"{
"email":"aa#aa.aa",
"password":"alcohol"}},
"headers":{
"Accept":"application/json,text,plain,*/*",
"Content-Type":"application/json;charset=utf-8"}},
"statusText":"Not Found"}
I am at a loss to understand why this works on an iPhone but not an Android phone.

It may be to do with the URL prefix. Have you tried using:
apiDomain = #"https://cues-server-dev.elasticbeanstalk.com"
or
apiDomain = #"http://www.cues-server-dev.elasticbeanstalk.com"
or some other variant.

How to use HttpWebRequest with async & await

I am new to Xamarin and C# as well. I try to make a Http request to my server with some information.
In general with android Native a uses AsyncTask and HttpClient for that. and build a json object or name value pair, and encrypt it to integrate information with the request.
But when I try to do the same with xamarin I get some problems.
if I try to import the namespace
using System.Net.Http.HttpClient
than my xamarin not have this namespace
Because of the above problem I try to use HttpWebRequest. But when I go for use it with the asyc and await I am not getting any response from server.
I am new to xamarin so I am not sure about async and await keyword.
I read lot of articles but No luck :(
on Click of the Button I call the below Method
public async Task<int> ValidateUser(){
try{
var request = HttpWebRequest.Create (URL);
request.Method = "GET/POST";
String postString = String.Format ("AAA ={0}&BBB={1}&CCC={2}", "111",
"222","333");
byte[] postByte = Encoding.UTF8.GetBytes (postString);
Stream st = request.GetRequestStream ();
//I am reaching here
Console.WriteLine("Check for Validity");
request.ContentLength = postByte.Length;
st.Write (postByte, 0, postByte.Length);
st.Close ();
Task<Stream> contentTask = request.GetRequestStreamAsync();
Stream response = await contentTask;
String str = response.ToString();
// this is not getting printed in Console
Console.WriteLine("=====>>"+str);
}
catch (WebException exception) {
string responseText;
using (var reader = new StreamReader(exception.Response.GetResponseStream())) {
responseText = reader.ReadToEnd ();
Console.WriteLine ("====Dude Error"+responseText);
}
}catch(Exception e){
}
return 1;
}
Any help will be appreciated

Consider using RestSharp, a component created for Xamarin to facilitate web requests. Click here for more info on the component. It will facilitate allot of things about webrequesting ( like serialization, automatic return type detection,... )
Your code would look something like this with restsharp:
public async Task<int> ValidateUser(){
var client = RestClient (URL);
var request = new RestRequest ("AAA ={0}&BBB={1}&CCC={2}", "111",
"222","333");
client.ExecuteAsync (request, response => {
WebApiResponse webApiResponse = new WebApiResponse ();
webApiResponse.Content = response.Content;
webApiResponse.StatusCode = response.StatusCode;
webApiResponse.ResponseStatus = (WebApiResponseStatus)response.ResponseStatus;
return webApiResponse.Content;
});
return -1
}

Using HttpWebRequest is a bad idea, instead it would be better to focus on why you don't have the System.Net.Http.* namespace. Imho the most likely cause is that you didn't add System.Net.Http as a reference to your project.
Here's how you add System.Net.Http.* to your project.
In Visual Studio 2013:
Open the solution
Open the project
Open the Solution Explorer
Right-click on References
Add Reference
Click on 'Search Assemblies'
Type in 'Http'
Select System.Net.Http
Press 'OK'
In Xamarin Studio:
Open the solution
Open the project
Open the Solution Explorer
Right-click on References
Edit References
Type in 'Http'
Select System.Net.Http
Press 'OK'
Afterwards there should be no problems resolving System.Net.Http when 'using System.Net.Http;'

unable to connect to JSON service in android application of Titanium studio

i am trying to do login application which takes id and password..when i click on logi button then it will connect to our local server by JSON..with the specified URL..the code is..
var loginReq = Titanium.Network.createHTTPClient();
loginReq.onload = function()
{
var json = this.responseText; alert(json);
var response = JSON.parse(json);
if (response.data.status == "success")
{ alert("Welcome ");
}
else
{ alert(response.data.status);
}
};
loginReq.onerror = function(event)
{
alert(event.toSource());
//alert("Network error");
};
loginBtn.addEventListener('click',function(e)
{ if (username.value != '' && password.value != '')
{
var url = 'our local url action=login&id='+username.value+'&pwd='+password.value;
loginReq.open("POST",url);
loginReq.send();
}
else
{
alert("Username/Password are required");
}
});
Here it is not connecting our URl..so it is entering into loginReq.onerror function...instead of loginReq.onload function..why it is throwing run time error.. The same code working fine with Iphone..
The Run Time Error is..
TypeError:Cannot call property toSource in object{'source':[Ti.Network.HttpClient],specified url} is not a function,it is a object.
This is wat the error..please let me Know...

Apparently the toSource() function does not exist in android, as it is an object. Try debugging and see what the object event contains.
You could do that by adding a line above the alert line, and adding a debug line to it.
Look in debug mode and see all variables

"toSource()" is not a documented function for either platform, and I also do not see it in the source for Titanium Mobile. If you aren't getting the error on iOS, I'm guessing it is because the error handler isn't getting called. Perhaps your emulator or device does not have internet access, whereas your iOS simulator or device does?
Regardless, error handling in the HTTPClient normally looks something like this:
loginReq.onerror = function(e)
{
Ti.API.info("ERROR " + e.error);
alert(e.error);
};