I'm trying to use T4MVC in my ASP.NET MVC4 application.
I'm inserting it in my view as shown below:
#using (Ajax.BeginForm(MVC.Check.Lead(),
The Lead method takes an integer ID parameter which is supplied in the form itself.
In the documentation T4MVC state that a parameter-less constructor should be auto generated however the compiler says that there isn't.
Why is it not generated?
Well I figured it out myself. My controller action returned a string which apparently is not suppported by T4MVC. So I changed it to partialviewresult and it works now.
Another possible reason (for future viewers) is that your action is inherited. It works but T4MVC will not automatically make your base actions virtual and it will not generate the parameter-less overload.
Related
I have a quick question on scope of ModelAttributes.
Dev. Env: Spring MVC 3.1/Java 6/JSP w/JSTL for Views
In my controller, I add an attribute to the model via
model.addAttribute(“appForResubmission”, appForResubmission);
In the JSP(served out in response to a GET request) I read it’s contents as:
${appForResubmission.appId}
— works fine and the data is shown on JSP as expected.
Upon submission of the JSP, in the same controller in a different method(in response to a PUT request), I try to read the attributes from the Model for any changes and I am doing this as
#ModelAttribute(“appForResubmission”) Application app
in the method signature.
However, all I get is a new Application object when I try to interrogate the object for data. Spring’s documentation says this kind of instantiation of a new object happens when the requested attribute does not exist in the Model.
What would cause the attribute to be lost? Any ideas? I am suspecting it is a scope issue someplace but I am not sure where the problem could be.
Any pointers you could provide is greatly appreciated?
Thank you,
M. Reddy
The scope of a modelattribute is the request, internally it is just equivalent to HttpSerletRequest.setAttribute("model", model).
If you want the model to be available in a different controller you probably have two options, one is to reconstruct it, based on what you submit to the controller or using your persistent source. The second option is for specific model attributes to be added to the session using #SessionAttribute({'modelname'}), but just be careful that you have to call SessionStatus.complete to remove the model added to the session later.
I need to get some Json to the client side from the server and it's somewhat troublesome as almost all tutorials assume an Ajax call to a separate action to get the Json.
This led me to think that there must be some reason why it is done this way. In Asp.Net MVC we can pass a Model along with the view to get the information but we can't seem to easily pass a Json object. Instead you are supposed to make a separate call to get this information.
What if the Json info is known when the page is generated, why not generate it at the same time?
I'm sorry if I wasn't clear enough. While it's nice to hear of ways to get Json to the client, the question is actually whether there is a specific reason the Ajax call method is much more popular, like security or anything like that.
Can you put something like this into your view? (rough pseudo code, assuming using a Razor view)
< script >
var myJSON = { Field: #model.Field, Field2: #model.Field2 };
< /script >
Because you do not need both at the same time... on the first call will be to get html (the view of the data - represented by a view model), and any ajax calls will be to get the possibly updated data (json serialized view model).
No reason why you can't. You could use the javacript serializer to create a JSON string that drop on the page. You could also create an action that return the json string that you called from a script tag.
What you want if you're using KnockOut, would be the Mapping plugin that turns an ordinary JS object, like that generated above, into an observable ready for KnockOut to use. See here from info. http://knockoutjs.com/documentation/plugins-mapping.html
You can use content-negotiation by setting accept header. This is considered a best practice (and according to some RESTful).
This needs to be supported and implemented at server as well. ASP NET MVC does not make it easy to support content-negotiation and you have to implement it yourself by if-else or using ActionFilter and implementing action selector.
I'm wondering if there is an ASP.Net MVC equivalent to PHP's require_once() function.
Lets say I need to call RenderAction to a particular action twice. However, inside the view that is rendered from said action, I need to print out some init scripts but only once.
Is there an easy mechanism to do this?
Should a flag be set in the controller and then passed into the view?
Thanks for any help you can provide.
Edit
Thanks for the responses. I know I can do this through the controller or temp data or some mechanism like that but wasn't sure if there was anything built into .NET MVC that would have done this for me automatically.
I am not aware of such equivalent.
Should a flag be set in the controller and then passed into the view?
That seems like a good way. The flag needs to be passed as argument to the controller action when using the RenderAction helper.
I am using in my views (asp mvc3/razor cshtml) references to the Request object (eg, #Request.Params["Name"]). Do you think this is a very bad practice? Should I rewrite the value in the controller Request.Params ["Name"] to ViewBag.Name and then use it in the view (#ViewBag.Name)?
Best practice is to use a model class. An instance of the model class is created or updated in your controller. Then the controller displays a strongly-typed view.
So I'd avoid direct access to the request from the view as well as the use of the view bag.
Should I rewrite the value in the controller Request.Params ["Name"] to ViewBag.Name and then use it in the view (#ViewBag.Name)?
Yes. You will avoid runtime errors if "Name" does not exist.
The IDE will not warn you of the NullReferenceException about to be thrown with the following code.
#Request.Params["Fake"].ToString()
Of course, you'll have to be careful about ViewBag.Fake being null as well.
I like to use the viewbag to store things not related to the model, for example if I have a dropdown containing locations. I like to store only the id of the selected location on the model and the locations in the viewbag, since is not needed to create a contact. I think that's the purpose of the viewbag.
For me the model is a bag or properties used in business operations, for example if I have a customer creation view using a NewCustomerModel, I don't wanna pollute my model with things like a IList<CustomerType> AND a SelectedCustomerTypeId property. I just want the second since is the one imma use to create the customer.
I am new to the MVC way of programming so please bear with my basic question !
I have a Status class with a default constructor (in an ASP.NET MVC application).
public Status()
{
this.DatePosted = DateTime.Now;
}
I noticed Fluent NHibernate calls this constructor each time it fetched a list of existing Status objects from the database. Hence, the constructor does not seem like the right place to initialize the date.
Where should I move this initialization ? Moving it to the Controller (Add action of Status controller) also seems to violate the principle that the Controller should not make any business decisions. Should I move it to the Status DAO then ? (In traditional ASP.NET Web Form applications I worked with, a DAO simply accepted a business object and saved it to the database and did not contain any logic)
I would like to know the right way to accomplish this. Is there another layer I am missing here where this initialization should take place?
I noticed Fluent NHibernate calls this
constructor each time it fetched a
list of existing Status objects from
the database. This does not seem right
This is exactly what is supposed to be happening. Why wouldn't an ORM call the default constructor for an object? I think every hand rolled DAL and ORM in the world would trigger DatePosted to be reset because thats just how constructors work.
Your DatePosted property should probably set via ModelBinding or manually in the controller and not be part of a constructor.