What are the disadvantages to using webparts in asp.net? Are they losing their popularity?
I was planning on creating a user defined Dashboard and was thinking of using Webparts, is this the way to go or is there another way of doing customisable dashboards these days? I would prefer not to have to use a 3rd party product.
To me, webparts are more of a sharepoint thing these days.
Other than that, with some design you can get all you need with user controls and some classes of your own to get common functionality and layout sorted out.
Say you have a base class called DashboardWidget that inherits from WebControl here you could define a overridable method
ProcessDataSource -> executes a query to a database or service and formats the results for presentation
And in the prerender method (or something similar along the asp.net lifecycle) you call ProcessDataSource (you could use the DataSource property most controls already have).
Then you inherit from DashboardWidget to make your controls and in the render method you override ProcessDataSource to get the info the way you need and the Render method to setup what to display.
Ideally you should define your own data source class to have a single place to define where to connect, how, credentials, etc..
As for the layout, newer versions of asp.net include several layout option you may use (and there is always pure html if you want)
I'm shooting from the hip a bit here, but that's a way to do it without involving webparts, that to me, are not that popular outside of sharepoint.
Hope anything of this helps
Related
Trying to craft a way for our designers to create custom asp.net webforms for our customers. The basic idea is that we have a general set of fields that can be saved, with each customer using a subset of those fields, each customer may have it's own names for similar concepts (ie one customer may use 'patient' and another 'customer'). Staying in customer context will help the designers build the correct form to meet the customers needs.
Now to do this I need to get as much as I can into the design experience as possible. I have a set of custom controls that derive from base controls like asp:TextBox and implements an interface to allows me to iterate over the controls and insert values from a data store, or fetch values to persist (Done). All of these controls need to be bound to a data point in my record object. I have a metadata system set up to allow the binding, but where I am running into trouble is in getting the list of available fields into a UITypeEditor. Namely, I haven't figured out how to (at design time) set the customer context on the form, and then access and use that value on each controls custom property editor (also at design time). Is this possible? Am I looking at this problem the wrong way? A form always has 1 and only one customer context. So in my forms project, each form will have a different customer id set to it.
As a second question how can I debug these editors? There is an expectation of web context in the editors, but there is no asp.net property grid. and even if there was, the editors are winforms components that wouldn't run in a browser.
I can include the code I currently have if it simplifies the problem, but even a simplified example is a half dozen classes.
I resolved these issues, posting here in case a general solution can be useful to anyone in the future.
I was able to get around this problem a bit by going the other way. My parent Page iterates over it's controls, and sets the CustomerId on all the controls that implement a specific interface.
As for debugging. Some refactoring got me to a place where I can easily swap out the webforms specific parts of my implementation for testing.
I've developed an ASP.NET user control, instances of which may appear several times on a single page. Without getting into too much application detail, when the value of any one of the instances changes, all of the other instances need to be refreshed. Currently, in order to accomplish this, I'm requiring that the consuming page implement a couple of methods which iterate through each control on the form, find all the instances of my user control, and call a Refresh method in each one.
Functionally, it's working perfectly. However, I'd like to force the developer of the consuming page to implement these two methods exactly as per my requirements. I could have them implement an interface, but that doesn't provide the functionality in each method. Or I could have them extend an abstract class, but in either case (interface or abstract class) how can I force them to inherit? I need something that will trigger a compiler error if the necessary abstract class is not extended by the consuming page. Any ideas?
Thanks.
You can enforce implementation by using 'abstract methods' in C# or using the 'MustInherit' keyword in VB.NET.
In your particular case, you're expecting the developer to essentially implement 'your' code to force the refreshing and this is something I wouldn't want delegate. Without knowing too many details I would be tempted to utilise the 'Observer' design pattern or possibly the 'Mediator' using either a separate object as a controller or even applying the controlling / publishing code to the webpage. Here's a practical example of the 'Observer' in ASP.NET.
HTH
Is it my understanding that Helper methods are really the place where you can do the hard core logic that we would have done in lets say custom controls in ASP.NET? For instance I work for a .com which uses classic ASP.NET. The nature of our site is VERY complex, so we reuse and render different forms for thousands of products. Every product could have a different configuration form. We have a very complext RenderForm.cs custom server control that performs all the logic. Based on some configuration settings from a table in the DB, it says ok, for Product 1123 it reads the setup (that our users confugure form our internal admin system) and takes that and spits out the dynamic form (using literal controls and what not) to the p age.
So I'm thinking MVC now. Yea yea, it's all done in the View. Well partially. You're still going to have a need to have some custom logic in some .cs where it's not all embeded in your view. That would be foolish to think you're not going to have some class that will spit out some HTML..like some very hard core extensive helper methods.
So my question is, are helper methods or class where you now do your custom server control type of logic? it's basically kind of the same concept in that you need a place to put your "hard core" HTML rendering logic in some class other than a controller. Your controller is not responsible for rendering. So helper methods I guess are the so-called custom server controls in a way that I have in classic ASP.NET, figuratively speaking. I just need a yes or now on is the consensus that helper methods is the place to do all my hard core reusable logic that spits out html to the page and where I can embed custom controls into my view? Looks like it.
"Helpers are essentially static classes, designed to contain the UI logic that otherwise clutters up your UI. Think of these as UI utilities." link text
Yes, that is right on. If you do it right, you will start with the HTML helpers that MVC gives you, and you will gradually build up your own set of helpers that do even more and more for your specific project. You can get to the point where your view has only a few lines of code, which say something like, "Render entire view for Product 1123". The helpers will become your own "language" of renderers specific to your project, and you will be applying configuration, validation and everything else in a very DRY (Don-t Repeat Yourself) manner. It's phenomenal.
Update: Of course, only presentation stuff should go in your helpers. The goal is to stay DRY in your views. You still need to be careful to put into your ViewModels the things that belong in the ViewModels.
I would say "no"... or rather "only where you have to". More often than not, you can instead do the logic in the Controller (or a Service) and end up passing all the data required back to the View in ViewData. Somtimes this will mean multiple Views from one ControllerAction, less often it will mean logic in your View, and occasionally it means HtmlHelpers.
When you decide to use Helpers, it should be with the consideration that this means generated markup that won't be... well, in your markup. If you have (or later hire) a designer, that can be a problem. Or if you need to make a minor change to your layout, where do you go first? Your View or your Helpers?
[Edit] Also should ask yourself this: where is my code more easily unit tested? In a Service class which is just handing back View Data, or in a class that builds entire chunks of HTML and returns them as a String? If you're using TagBuilder, as you probably should be, then any change in the implementation of TagBuilder (even a change of whitespace handling) will break tests on a Helper without your code changing.
I'm not saying "don't use Helpers", I'm saying "don't abuse Helpers".
In traditional ASP.NET Web Form applications, UserControls are a great way to encapsulate functionality so that it can be reused. However, UserControls don't fit well into the MVC model. They often make heavy use of ViewState and they blur the seperation of concerns that MVC promotes.
My question is, how do you best bundle a piece of functionality so it can be shared across MVC applications?
As an example, consider a from/to date-selector UserControl that:
allows a user to select two dates, either using a javascript overlay or by typing in day, month and year into seperate fields
can be configured to default to either today and tomorrow's dates or to dates of the developer's choosing
validates the dates that comes back from the user to ensure the from date is before the to date
exposes From and To properties that can be accessed by code-behind
How would I best build something like this in .NET MVC so that I can easily reuse it?
Note that to fully emulate User Control's functionality the MVC component would have to manage the submitted form data and validation - not just the presentation.
In general I would agree that user controls are nice in terms of encapsulating UI stuff, but I don't think too much has really changed in MVC. If I remember right re-using user controls across classic Asp.net projects was a pain and was never really the best way to truly create reusable components. Most UI toolkits that you bought for classic ASP.net didn't give you user controls, they gave you essentially server controls and javascript controls.
In your example, I would probably create or find a jquery (or ur framework of choice) plugin that did what you wanted on the client side. You could also build a C# wrapper around it similar to what Telerik did with some of the jquery UI controls. I do think that the word code-behind and even viewstate will disappear from your vocabulary the more you get into MVC.
If you look at what open source projects are out there for MVC you will get your answer in terms of what you should be doing.
The MVC Contrib app adds a lot of features by creating extension methods and helpers. Their grid control is a typical way to create a reusable component that you could use across projects
Telerik, created some extensions that wrap jquery controls and do asset management.
Finally I think if you look to the future, MVC has areas, which if I interpret it right will give you the ability to break your project apart into multiple smaller projects.
Besides what is already suggested, ASP.NET MVC v2 will have generic templated input controls, see here. You can read how other people do similar techniques, for example, here:
We have
exactly 1 method call for generating a
form element, “Html.InputFor”. As
part of that “InputFor”, it examines
an input specification, that collects
the PropertyInfo, any attributes, the
type, any modifiers called, and
selects an appropriate InputBuilder.
Call InputFor(p => p.Id) and Id is a
GUID? That creates a hidden input
element. Call InputFor(p =>
p.Customer.Address) and Address is a
complex type? That looks for a
partial with the same name of the type
Having considered the helpful answers from others, I will have a go at answering my own question.
It seems to me that the key difficulty with emulating UserControls in MVC is that they crosscut the concerns that MVC aims to seperate. The from/to date selector UserControl in my example incorporates elements of Model, View, Control and interation. UserControls' ability to bundle all this together is exactly the reason that they don't fit well into MVC.
That means that to create a psuedo-UserControl in MVC requires four seperate pieces:
A Model class - in this case an Interval class or similar
A PartialView that knows how to render the Model to HTML
A jQuery script to layer interactivity on top of the PartialView's HTML
A ModelBinder that can deserialise postdata into an instance of the Model class.
The ModelBinder is important because it deals with data coming back from the user. Without it, every Controller that wanted to display a to/from date selector in any of its Views would have to know how to assemble the six postdata fields - and how to cope if they were invalid or some were missing.
Two ways that I can think of. A partial view though this doesn't really transfer well from app to app because you are moving around ascx files. Not a big pain but not my flavour.
I prefer to use WebControls. They are super easy in mvc and all you need to do is reference the library in the project and possibly in your config file and there you go.
I think some of the answers have missed out on the postback functionality of controls. One way you could handle that is to pass any generic information via ViewData when rendering your partial view. That could then post back to its own control, which in turn could redirect to the UrlReferrer.
Its a little messy and use of UrlReferrer poses a security risk. But it is one way around the problem
You can create a jQuery plugin.
As user-controls provided in ASP.NET Webforms, MVC provide a lot of ways to make the controls and code that can be reused in other app.
Using Partials If your partial code have some C# logic and render the html using Razor/aspx code then it's bst to maintain them in razor file.
Write JavaScript Functionality as plugin If you maintain your code and write it as better as it can be used in other app then it would be a huge advantage for you. Next time when you work on other app just open this solution copy it and modify it. Write JavaScript code that can be used as plugin maybe take some more brainstorming.
Write Code As a Separate C# library If some code is too common for every app you make.for example you write a member authentication system or some global function (C#) that are used in every app you made then maintain them in a separate solution so it can be used in other app you made whenever you trying to make a new app in future.
I've been trimming the UI of our website by doing the following in the onload event of that control:
btnDelete.isVisible = user.IsInRole("can delete");
This has become very tedious because there are so many controls to check again and again. As soon as I get it all working, designers request to change the UI and then it starts all over.
Any suggestions?
One simple suggestion would be to group controls into panels based on access rights
Something I have done before has been to create a custom page class (Actually, I do this part on every project) that each ASP.NET Page inherits.
This page class contains an IsAdmin property.
I then subclass the commonly used controls that may or may not be visible between modes into custom controls, and add code to check the Pages IsAdmin property.
All this is maybe an hour of work, but if you build pages using these controls, they manage their mode automatically.
Another fun timesaving tip is if you need to flip the page in and out of readonly mode. I added a property to the main base class, and then added a custom control that renders a textbox in one mode, and a label in the other.
Again, a little bit of time on the components, but then you can create a readonly version of the page in 2 lines of code...Very worth it.
You may be thinking of the situation in the wrong way. Instead of thinking of individual controls, think of it in terms of business roles and what they have the ability to do. This goes along with grouping controls into panels for access rights. For example, maybe only managers have the ability to delete and do other things, and you have a role for managers that you check. This way if there are changes, you can just move users into different roles. Business rules should not change drastically. There will always be tweaking as new positions gain more responsibility, but thinking of it in this way should minimize the number of changes to be made.
A quick and dirty option is using the asp:loginview controls, which can be wired up to user roles.
Not as elegant as the custom page class option suggested by Jonathan, and can be a bit of a performance hit if they are all over the page.