I have a controller class that makes a search on the Student Database and displays its
information. Right now no matter if a particular student is found or not, it displays the same screen.
I am planning to show a different view if backend search doesnt return any data. For this
I coded my controller with if else block (data found: show view, else show different view) but
it doesnt seem to be working. In any case I am seeing the same view returned back. In this sample
student/homePage. What am I doing wrong here?
#Controller
public class StudentController extends BaseClassController
{
#RequestMapping( value = "/student/studentSearch.html", method = RequestMethod.POST )
public String searchStudent( Arguments )
{
if( bundleStudentBean.getRollNum() != null)
{
try
{
//Call Service layer and get the data
//Set into a model
}
catch( ServiceException e )
{
// Some exception occured
}
catch( Exception e )
{
//print error trace
}
//Student Found: Show student homepage
return "student/homePage";
}
//No Student Found: Show splash page
return "student/noDataPage";
}
}
Instead of checking whether the rollNum to null,better check whether it's value is zero. Chances are more that the function returns zero even when youi give no value into it.Most probably in the database you would have set the column to be not null and int
Good practice: Controller methods should be as lightweight as possible.
Bad practice: using Exceptions as control flow.
Spring MVC has a nice way of mapping business exceptions to custom views using ExceptionHandlers. I assume this is only one of the cases where a Controller is looking for a student and finds none - using ExceptionHandlers should help you write readable, lightweight Controllers.
Related
I'm investigating Web Api in ASP.NET vNext using the daily builds. In a web api 2x project, I use HttpParameterBinding and ParameterBindingAttribute in some situations (see http://bit.ly/1sxAxdk); however, I can't seem to find either in vNext. Do/will these classes exist? If not, what are my alternatives?
Edit (1-22-15):
I want to be able to serialize a complex JS object to a JSON string, put the JSON string in a hidden form field (say name="data"), submit the form, and then bind my parameter to that JSON object on the server. This will never be done by a human, but rather by a machine. I also want this very same mechanism to work if the JSON is sent directly in the request body instead of form data. I also need this to work for several different types of objects.
I've been able to accomplish this scenario in Web Api 2.2 in a few different ways, including a custom ModelBinder; however, I remember reading an MSFT blog post that suggested to use a ModelBinder for query string binding, formatters for request body, and HttpParameterBinding for more general scenarios. Is it okay to read the request body in a ModelBinder ASP.NET 5, or is there a better mechanism for that? If so, then case closed and I will port my ModelBinder with a few minor changes.
I'm not sure that IInputFormatter will work for me in this case either.
Here are two rough approaches
Approach 1:
A quick and dirty approach would be to start with a Dto model
public class Dto
{
public Serializable Result { get; set; }
public Serializable FromForm
{
get { return Result; }
set { Result = value; }
}
[FromBody]
public Serializable FromBody
{
get { return Result; }
set { Result = value; }
}
}
public class Serializable
{
}
And an action method
public IActionResult DoSomething(Dto dto)
{
// Do something with Dto.Result
}
Then write a custom model binder for Serializable, that just works with Request.Form this way you never actually read the body yourself, and Form only reads it if it of type Form.
The down side of this is that ApiExplorer will not provide correct details (but I think since this is none-standard you are going to be in trouble here anyways).
Approach 2
You can alternatively just use the code from BodyModelBinder and create a custom binder for Serializable type above, that first tries to get it from the Form, and if it fails tries to get it from the Body. The Dto class in that case is not necessary.
Here is some pseudo code
if (inputType is yourtype)
{
if (request.Form["yourkey"] != null)
{
Use Json.Net to deserialize your object type
}
else
{
fall back to BodyModelBinder code
}
}
With this approach you can make it generic, and ApiExplorer will say the way to bind the type is unknown/custom (we haven't decided on the term yet :) )
Note:
Instead of registering the model binder you can use the [ModelBinder(typeof(customBinder))] attribute to apply it sparingly.
Here is a link to the BodyModelBinder code.
There is a new [FromHeader] attribute that allows you to bind directly to http header values if that is what you need.
https://github.com/aspnet/Mvc/issues/1671
https://github.com/aspnet/Mvc/search?utf8=%E2%9C%93&q=fromheader
I've just recently started learning MVC patterns, originally in android but currently with spring MVC framework. I'm wondering if it is more appropriate to have testing/exception handling in the model or a controller. What I mean is, say I had some field in the model which should be restricted to some values, or a range of values; should I be testing the inputs and throwing exception in the model and having the controller catch them, or should the controller check inputs on it's own before forwarding inputs to the model?
My concern with testing in the controller is that I may need to check values in several spots whereas if I were to test in the model it's only done in one place. My concern with checking inputs in the model is that, for some reason, that seems really odd to me; then again I am new to this pattern so I don't really know yet.
What is the norm? What is recommended?
Thanks everyone
It is appropriate to have testing and/or exception handling in the model and the controller, which ever is most appropriate to the handling of the exception.
For example, if you want want to parse a number from a string and use a default value when the string does not contain a number and you are parsing in the model, then you should handle the numberformatexception in the model.
I think of this as an "expected" exception.
private String blammyValue;
public int getBlammyAsInt()
{
int returnValue;
try
{
returnValue = Integer.parseInt(blammyValue);
}
catch (NumberFormatException exception)
{
returnValue = -1; // some default value
}
return returnValue;
}
If the exception is something that is out-of-the-ordinary,
like a database exception,
and for which there is no reasonable default behavior,
then catching it in the controller makes sense.
In my edmx model are 2 related tables: Challenge and ChallengeNote (has FK back to ChallengeID)
I can do this in breeze all day long
var qry = dataservice.getQuery("Challenges");
However, this fails every time:
var qry = dataservice.getQuery("Challenges").expand("ChallengeNotes");
The searchFailed is called and is the only error information in the console.
return dataservice.execute(qry.inlineCount(true))
.then(seachSucceeded)
.fail(searchFailed);
Does Breeze support relational data like this?
Does one need to write some custom code to support?
What am I missing?
Here's related answered question, but I was already following (unless I missed something) the answer's solution (and why I have the 2 context.Configuration settings in my ContextProvider).
breezejs-error-when-loading-an-entity-with-related-data
Here's another similar question that's been unanswered breeze-expand-query-fails-with-object-object-has-no-method-getproperty
Here's my provider code (want to use the BeforeSaveEntity override further on in the project):
public class ModelProvider : EFContextProvider<ModelEntities>
{
public ModelProvider()
: base()
{
this.Context.Configuration.LazyLoadingEnabled = false;
this.Context.Configuration.ProxyCreationEnabled = false;
}
}
Here's my controller code:
[BreezeController]
public class DataController : ApiController
{
readonly ModelProvider _contextProvider = new ModelProvider();
[HttpGet]
public string Metadata()
{
return _contextProvider.Metadata();
}
[Queryable(AllowedQueryOptions = AllowedQueryOptions.All)]
[HttpGet]
public IQueryable<Challenge> Challenges()
{
return _contextProvider.Context.Challenges.Include(x => x.ChallengeNotes);
}
[HttpPost]
public SaveResult SaveChanges(JObject saveBundle)
{
return _contextProvider.SaveChanges(saveBundle);
}
[HttpGet]
public IQueryable<ChallengeNote> ChallengeNotes()
{
return _contextProvider.Context.ChallengeNotes;
}
}
When I browse to the URL, it's including the related entity:
http://localhost:53644/breeze/data/Challenges?$filter=Active%20eq%20true&$top=10&$expand=ChallengeNotes&$inlinecount=allpages
Here is the data coming from the Controller
At this point all things, imo, are pointing to Breeze configuration on either the Server or Client.
TIA
Breeze absolutely does support this, but you do need to make sure that your Entity Framework model is set up correctly. Take a look at the DocCode sample in the Breeze zip for a number of examples of using both expand (client side) or EF include (server side) clauses.
One guess about your problem is that you are using the Breeze camelCasing naming convention and therefore your "expand" clause should be
var qry = dataservice.getQuery("Challenges").expand("challengeNotes");
i.e. "challengeNotes" (note the casing) is the name of the client side property that corresponds to a server side property of "ChallengeNotes". To clarify, "expand" clauses take the names of client side "properties" as parameters and property names are what are transformed as a result of the Breeze.NamingConvention.
In contrast, a query resource name i.e. "Challenges" in your example is the name of the server side resource ( as a result of marking your "Challenges" method with the [HttpGet] annotation. This name is NOT affected by the NamingConvention.
Side notes: Your example has both an expand and an Include clause. Either of these is sufficient all by itself. You do not need both. In general you can either include an "expand" clause in your client side query OR have an Entity Framework "Include" clause on the server. The advantage of the first is that you can control the expand on the client, the advantage of the second is that you can insure that every query for a specified resource always fetches some related entities.
Hope this helps!
I have two actions in my controller which are sharing part of logic responsible for selecting the view. How Can I make this part common accross actions. Example:
Controller Document
Action Open
if there is one document found and is type X, display it using OpenX View
if there is one document found and is type Y, display it using OpenY View
if there are more than documents found, display list using List View
if there are no documents found, display error using Error View
Action OpenMetaData
if there is one document found, display it using OpenMetaData View
if there are more than documents found, display list using List View
if there are no documents found, display error using Error View
As you can see, points 3,4 are the same as 2,3
I would like to create something like
public DocumentController
{
public ActionResult Open( ... )
{
var dataFromWebService = service.GetData( ... );
return ViewSelector.GetLaunchView(dataFromWebService);
}
public ActionResult Open( ... )
{
var dataFromWebService = service.GetData( ... );
return ViewSelector.GetOpenMetaData(dataFromWebService);
}
}
public class ViewSelector
{
public static ActionResult GetLaunchView(DataFromWebService dataFromWebService)
{
if( dataFromWebService contains document type X)
return new ViewResult("OpenX",data);
if( dataFromWebService contains document type Y)
return new ViewResult("OpenY",data);
return CommonLogic(dataFromWebService);
}
public static ActionResult GetOpenMetaData(DataFromWebService dataFromWebService)
{
......
}
private static ActionResult CommonLogic(DataFromWebService dataFromWebService)
{
.... Common logic
}
}
I would like to do this to make my Controller as clean as possible.
Can I create ViewResults outside controller, attach data to them are return them in the action ?
Is this good or bad design ?
Maybe someone have better idea how to handle this
If you don't need to access any of the contexts of the controller you can create the results outside the controller. In your case I would consider making the GetOpenMetaData() and GetLaunchView methods private methods of the controller.
If you need to share it accross multiple contollers you could also consider putting it into an abstract BaseController and let your controllers inherit from it.
I'm using logical delete in my system and would like to have every call made to the database filtered automatically.
Let say that I'm loading data from the database in the following way :
product.Regions
How could I filter every request made since Regions is an EntitySet<Region> and not a custom method thus not allowing me to add isDeleted = 0
So far I found AssociateWith but I'd hate to have to write a line of code for each Table -> Association of the current project...
I'm looking into either building generic lambda Expressions or.. something else?
You could create an extension method that implements your filter and use that as your convention.
public static class RegionQuery
{
public static IQueryable<Region> GetAll(this IQueryable<Region> query, bool excludeDeleted=true)
{
if (excludeDeleted)
return query.Regions.Where(r => !r.isDeleted);
return query.Regions;
}
}
So whenever you want to query for regions you can make the following call to get only the live regions still providing an opportunity to get at the deleted ones as well.
context.Regions.GetAll();
It my be a little wonky for access the Products property, but still doable. Only issue is you would have to conform to the convention. Or extend the containing class.
someProduct.Regions.GetAll();
I hope that helps. That is what I ended up settling on because I haven't been able to find a solution to this either outside of creating more indirection. Let me know if you or anyone else comes up with a solution to this one. I'm very interested.
It looks to me like you're using a relationship between your Product and Region classes. If so, then somewhere, (the .dbml file for auto-generated LINQ-to-SQL), there exists a mapping that defines the relationship:
[Table(Name = "Product")]
public partial class Product
{
...
private EntitySet<Region> _Regions;
[Association(Storage = "_Regions")]
public EntitySet<Region> Regions
{
get { return this._Regions; }
set { this._Regions.Assign(value); }
}
...
}
You could put some logic in the accessor here, for example:
public IEnumerable<Region> Regions
{
get { return this._Regions.Where(r => !r.isDeleted); }
set { this._Regions.Assign(value); }
}
This way every access through product.Regions will return your filtered Enumerable.