Retrieve only one item with MVVM light in Silverlight - silverlight

To grab some content from a WCF Data Service into my View Model is straight forward:
public const string RequestsPropertyName = "Requests";
private DataServiceCollection<Request> _requests = null;
public DataServiceCollection<Request> Requests
{
get { return _requests; }
set
{
if (_requests == value) { return; }
var oldValue = _requests;
_requests = value;
RaisePropertyChanged(RequestsPropertyName, oldValue, value, true);
}
}
and then
Requests.LoadAsync(query);
But what if I have a property which is not a collection?
public const string RequestDetailsPropertyName = "RequestDetails";
private Request _requestDetails = null;
public Request RequestDetails
{
get { return _requestDetails; }
and so on.
Where do I get the 'LoadAsync(query)' method from?
Thank you,
Ueli

This is a pretty simple thing to do. You just need to use the DomainContext in your application. This is where you create your query from, then apply the result to your property.
Here is an example of what this might look like in your code:
void LoadRequest(int requstID)
{
var query = workContext.GetRequestByIDQuery(requestID);
workContext.Load(query, lo =>
{
DispatcherHelper.CheckBeginInvokeOnUI(() =>
{
if (lo.HasError)
throw lo.Error;
else
RequestDetails = lo.Entities.Single();
});
}, null);
}
In this example, the workContext object is the DomainContext. The query is an specific version on the server - you can also just contruct the query client side with:
.Where(r => r.RequestID == requestID)
After the async call, it thows any errors that occurred from the async call, and then returns the only entity returned. If you get more than 1 entity, you might use .First() instead.
If this is not enough to get you going, let me know and I can explain further.

Related

Filter a broadcasted property in Angular 9

I have a dbService that calls the database!
//DB service code -----------------------
private changedEvents = new BehaviorSubject<IEvent[]>(null);
broadCastEvents = this.changedEvents.asObservable();
getEvents() {
this.http.get<IEvent[]>(this.configUrl + 'Event/GetEvents').subscribe(
(data: IEvent[]) => {
this.changedEvents.next(data)
});
}
In my component on ngOnInit I starts listening to this
ngOnInit(): void {
this.dbService.broadCastEvents.subscribe(data => {
this.events = data;
})
// this.dbService.getEvents();
}
Now all of this working like a charm! But now I'm only interested in records where this.events.type == 2
I tried by a standard filtering like below!
ngOnInit(): void {
this.dbService.broadCastEvents.subscribe(data => {
this.events = data.filter(event => event.eventTypeRefId == 2);
})
// this.dbService.getEvents();
}
But it results in the following Error!? Any ideas how to this in a better way (that works :-))
core.js:6241 ERROR TypeError: Cannot read property 'filter' of null
at SafeSubscriber._next (start-training.component.ts:26)
at SafeSubscriber.__tryOrUnsub (Subscriber.js:183)
at SafeSubscriber.next (Subscriber.js:122)
at Subscriber._next (Subscriber.js:72)
at Subscriber.next (Subscriber.js:49)
at BehaviorSubject._subscribe (BehaviorSubject.js:14)
at BehaviorSubject._trySubscribe (Observable.js:42)
at BehaviorSubject._trySubscribe (Subject.js:81)
at BehaviorSubject.subscribe (Observable.js:28)
at Observable._subscribe (Observable.js:76)
ngOnInit(): void {
this.dbService.broadCastEvents.pipe(filter(event => event.eventTypeRefId == 2)).subscribe(data => {
this.events = data
})
// this.dbService.getEvents();
}
Reference:
https://rxjs-dev.firebaseapp.com/guide/operators
There are multiple ways for it. One way is to use array filter like you did. Other way would be to use RxJS filter pipe as shown by #enno.void. However both these methods might still throw an error when the notification is null. And since the default value of your BehaviorSubject is null, there is high probability of hitting the error again.
One workaround for it is to use ReplaySubject with buffer 1 instead. It's similar to BehaviorSubject in that it holds/buffer the last emitted value and emits it immediately upon subscription, except without the need for a default value. So the need for initial null value is mitigated.
Try the following
private changedEvents = new ReplaySubject<IEvent[]>(1);
broadCastEvents = this.changedEvents.asObservable();
...
Now the error might still occur if you were to push null or undefined to the observable. So in the filter condition you could check for the truthiness of the value as well.
ngOnInit(): void {
this.dbService.broadCastEvents.subscribe(data => {
this.events = data.filter(event => {
if (event) {
return event.eventTypeRefId == 2;
}
return false;
});
});
}

Byte array and JSON in [FromBody]

I am trying pass an object which consists of different data type. I am always getting null value for orderDetails in Web API.
However if do this,
purchaseOrder.Attachments = null,
in the client then orderDetails is no longer null and I have other informations like "SendEmail" and PurchaseOrderNumber.
It looks I might not be correctly set the parameter in the client (angular 2).
However testing the same Web Api method from Console app works fine and I am not getting a null value.
Do I need to separate the JSON data and byte array?
regards,
-Alan-
Models
public class Attachments
{
public int AttachmentId { get; set; }
public string FileName { get; set ;}
public byte[] FileData { get; set ;}
}
public class UpdatePurchaseOrderViewModel
{
public bool SendEmail { get; set; }
public int PurchaseOrderNumber { get; set; }
public Attachments Attachments { get; set;
}
Here is my Web API put method definition
[HttpPut("AddPurchaseOrderNumber/{purchaseOrderId}")]
public StatusCodeResult AddPurchaseOrderNumber(int purchaseOrderId, [FromBody] UpdatePurchaseOrderViewModel orderDetails)
{
try
{
var status = _service.AddPurchaseOrderNumber(purchaseOrderId, orderDetails);
if (status == 200)
_unitOfWorkAsync.SaveChanges();
else return StatusCode(status);//No Data
}
catch
{
return StatusCode(400); // Bad Request
}
return StatusCode(200);//OK
}
Typescript snippet
let headers = new Headers();
headers.append('Content-Type', 'application/json');
headers.append('Accept','application/json');
let options = new RequestOptions({ headers: headers });
var body = JSON.stringify(
purchaseOrder
);
var uri = 'http://localhost:33907/api/purchaseorder/addpurchaseordernumber/' + purchaseOrderId;
return this._http.put(uri, body , options)
.map((response: Response) => {
let data = response.json();
if (data) {
return true;
}
else {
return false;
}
})
Update
The orderDetails is created as below
let file = Observable.create((observer) => {
let fr = new FileReader();
let data = new Blob([this.attachment]);
fr.readAsArrayBuffer(data);
fr.onloadend = () => {
observer.next(fr.result);
observer.complete();
};
fr.onerror = (err) => {
observer.error(err);
}
fr.onabort = () => {
observer.error("aborted");
}
});
file.map((fileData) => {
//build the attachment object which will be sent to Web API
let attachment: Attachments = {
AttachmentId: '0',
FileName: this.form.controls["attachmentName"].value,
FileData: fileData
}
//build the purchase order object
let order: UpdatePurchaseOrder = {
SendEmail: true,
PurchaseOrderNumber:this.form.controls["purchaseOrderNumber"].value * 1, //for casting purpose
Attachments: attachment
}
console.log("Loading completed");
return order;
})
When sending objects that have byte arrays as a property back and forth between a client to a WebAPI endpoint, I typically use a DTO that stores the property to explicitly define it as a Base64 string. On the server side I map the DTO to my entity by converting the Base64 string to / from the byte array for server side operations and storing in the database.
The serializer will do something like this automatically but the format passed from JavaScript may not match what the WebAPI JSON serializer is expecting (which is why it's working from your C# Console App).
You didn't include how you are creating the purchaseOrder object in your JavaScript so I can't comment on how that object is being setup - which may be where your issue is.

Anotar.Serilog and logging

I premit that I'm quite new to Anotar / Serilog, I've my WPF application that uses the Repository Pattern and I've the repo strucured as
public class CalendarRepository : DefaultRepositoryBase, ICalendarRepository
{
public Task<IList<CalendarTemplate>> GetCalendarTemplatesAsync(int? template)
{
JsonServiceClient client = GetServiceStackClient();
var request = new CalendarTemplatesRequest
{
Template = template
};
return client.PostAsync(request);
}
public Task<IList<Currency>> GetCurrenciesAsync(int? currency)
{
JsonServiceClient client = GetServiceStackClient();
var request = new CurrenciesRequest
{
Currency = currency
};
return client.PostAsync(request);
}
public Task<IList<CurrencyCalendar>> GetCurrencyCalendarsAsync(IEnumerable<int> currencies)
{
JsonServiceClient client = GetServiceStackClient();
var request = new CurrencyCalendarsRequest
{
Currencies = currencies
};
return client.PostAsync(request);
}
Right now I was logging in the viewmodels as
LogTo.Information("Getting calendar currencies {SelectedCurrencies}",selectedCurrenciesId.Select(x=>x.Id));
var items = await repository.GetCurrencyCalendarsAsync(selectedCurrenciesId.Select(x => x.Id));
I was wondering if there's an Attribute that I can apply to a class in order to automatically log the Method and the parameters.
Right now my logged is configured as
var log =
new LoggerConfiguration().MinimumLevel.ControlledBy(
levelSwitch: new LoggingLevelSwitch(LogEventLevel.Debug)).WriteTo.File(#".\logs\serilog.log",outputTemplate: "{Timestamp: yyyy-MM-dd HH:mm:ss.fff} [{Level}] [{SourceContext}] {Message}{NewLine}{Exception}").CreateLogger();
Serilog.Log.Logger = log;
Thanks
You can get the method name and line number by adding {Method} and {LineNumber} to the output template respectively.
As far as I know, there is no way to automatically log the parameters; you would need to do this manually.

Save a value to Database - MVC

I am trying to save a value in the "UserController" but I cannot seem tog et it to save to the database.
I can get the database value as stored in the UserController to change so that when the value is submitted and the view is refreshed it looks as though it was stored. (ie. changing from test to tested) However, as soon as I refresh the page again it returns to the previous value and the database shows no change throughout this.
UserController:
var g = httpPost.VanityUrl;
DB.ppUser_editUser(g);
ppUser_editUser in ppUser:
public ppUser ppUser_editUser(string personVanity)
{
ppUser user = SessionUser.LoggedInUser.Person;
user.VanityUrl = personVanity;
BaseDB.SubmitChanges();
return user;
}
EditProfile View:
<div>
#Html.LabelFor(m => m.VanityUrl, "Edit your Custom Url:")
#Html.TextBoxFor(m => m.VanityUrl, new { maxlength = 15 })
</div>
BaseDB:
public partial class StudioKit_MVC3Repository : IDisposable
{
private StudioKit_MVC3ModelsDataContext _BaseDB;
public StudioKit_MVC3ModelsDataContext BaseDB
{
get
{
if (_BaseDB == null)
{
if (StudioKit_MVC3Config.EnvironmentDetail.Name == "Production")
{
_BaseDB = new StudioKit_MVC3ModelsDataContext(StudioKit_MVC3Config.EnvironmentDetail.ConnectionString);
}
else
{
var sqlConnection = new SqlConnection(StudioKit_MVC3Config.EnvironmentDetail.ConnectionString);
var conn = new ProfiledDbConnection(sqlConnection, MiniProfiler.Current);
_BaseDB = new StudioKit_MVC3ModelsDataContext(conn);
}
}
return _BaseDB;
}
}
}
Edit:
I figured out the problem. I was saving the value to the session user instance and not the actual database. I got rid of the method and in the controller I simply put:
ppUser check = DB.ppUser_GetUserByPersonID(model.cskPersonID);
check.VanityUrl = httpPost.VanityUrl;
DB.Save();

silverlight, using Observables on WCF calls, casting IEvent<T> where T : AsyncCompletedEventArgs

i have a question using Observables in Silverlight 4 to make WCF calls.
Consider the simple webservice call below.
var adminclient = ServiceProxy.WithFactory<AuthenticationClient>();
var results= Observable.FromEvent<AuthorizeAdministratorCompletedEventArgs>(
s => adminclient.AuthorizeAdministratorCompleted += s,
s => adminclient.AuthorizeAdministratorCompleted -= s).ObserveOnDispatcher();
adminclient.AuthorizeAdministratorAsync();
results.Subscribe(e =>
{
//Enable UI Button
});
i have implemented an extension method, that wraps the subscribe method, it does some error validation on the return.
On the return results.Subscribe(e =>
e is System.Collections.Generic.Event<AuthorizeAdministratorCompletedEventArgs>
almost every query will have a different return type such as:
e is System.Collections.Generic.Event<AsyncCompletedEventArgs>
if i had a wrapper that looked something like this, how can i cast every type of xxxCompletedEventArgs to its base type AsyncCompletedEventArgs so that i can access e.EventArgs and inspect the Error property
public static IDisposable Subscribe<TSource>(this IObservable<TSource> source, Action<TSource> onNext = null, Action onError = null, Action onFinal = null)
{
Action<TSource> onNextWrapper = (s) =>
{
var args = (System.Collections.Generic.IEvent<AsyncCompletedEventArgs>)s;
try
{
if (WCFExceptionHandler.HandleError(args.EventArgs))
{
if (onNext != null)
onNext(s);
}
else
{
if (onError != null)
onError();
}
}
finally
{
if (onFinal != null)
onFinal();
}
};
return source.Subscribe<TSource>(onNextWrapper, (e) => { throw e; });
}
The code above will fail
Unable to cast object of type 'System.Collections.Generic.Event1[MyProject.Provider.AuthorizeAdministratorCompletedEventArgs]' to type 'System.Collections.Generic.IEvent1[System.ComponentModel.AsyncCompletedEventArgs]'
This is the method definition of WCFExceptionHandler.HandleError(args.EventArgs))
public static bool HandleError(AsyncCompletedEventArgs e)
I'd probably change you extension method so that it acts to handle the the events as a non blocking operator (much the same as the majority of the Rx extension method operators). Something like:
public static IObservable<IEvent<TEventArgs>> GetHandledEvents<TEventArgs>(this IObservable<IEvent<TEventArgs>> source)
where TEventArgs : AsyncCompletedEventArgs
{
return Observable.CreateWithDisposable<IEvent<TEventArgs>>(observer =>
{
return source.Subscribe(evt =>
{
try
{
if (WCFExceptionHandler.HandleError(evt.EventArgs))
{
observer.OnNext(evt);
}
else
{
observer.OnError(new Exception("Some Exception"));
}
}
finally
{
observer.OnError(new Exception("Some Other Exception"));
}
},
observer.OnError,
observer.OnCompleted);
});
}
Then call it through:
results.GetHandledEvents()
.Finally(() => DoSomethingFinally())
.Subscribe(e =>
{
//Enable UI Button
},
ex => HandleException(ex),
() => HandleComplete());
I think this should solve your issues as the events will funnel through as their original type and it ensures that HandleError gets event args that are the correct type.

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