Skip to main content

70-562 User Controls



Copying and pasting a group of control might be ok if they have minimal business logic behind, but if the control has considerable business logic behind it, it might be better to group them in a user control and copy just this one control on each page.

A user control is a like a little page that you embed within other page, they are inteded for use within a single site, so it's ok to put site specific business logic in them.

Custom controls are, like the ones in the toolbox, created from scrach and inherit from a base class, and the result is an assembly containing the control.

User controls are often used for header, footers, and side panels.

To add a user control you can drag and drop it in the page in design mode, or add in the aspx page by adding a register directive that has a src, tagname, tagprefix. And will be referenced by it's prefix:tagname and an id specific to the instance of the control.

An example,a user control can be as simple as a drop down list that provides states of a country. Since the states don't change often, they CAN be hardcoded in the control rather than comming from a db.
In this example, the events exposed by the user control have to be defined, all events of the drop down list are private to the user control. The user control will raise an event that will be handled by the page hosting the user control. This is because a user control contains usualy many controls and some might have the same events. The page then has an event handler for the selected index changed for the user control, which can be hooked up to the user control's delegate, this can be done in the Page_Load or OnInit of the page.




Comments

Post a Comment

Popular posts from this blog

Rxjs Forkjoin vs Zip

These Rxjs combination operators are handy to make Rest calls in parallel and combine their results. Both take n observables and will return the results, with the difference that forkJoin will complete even if one of the nested observables errors of completes.
Post a Comment
Read more

React JS Patterns

React JS is always evolving, and evolving quickly. These evolutions can be very significant ones, for example, the addition of hooks. React has a lot of code patterns, often these patterns are motivated by the DRY and/or the open-close principle. These patterns sometimes come in to replace a previous one, yet the previous ones still stays in use, as a consequence, the list of patterns keep growing. The goal of the next few posts will be to list the patterns commonly used in React JS developpement. Some patterns are more specific to JSX and I will start with these, and maybe add patterns specific to Redux.
4 comments
Read more

Javascript: Closure and Lexical Scope

The two are separate topics, I just happen to put them in the same post for now. Closure Closure is the capability to remember it's lexical scope, even when executed outside it's lexical scope. If two inner functions, are within the same scope, they share the same closure.     Lexical scope The lexical scope is the scope in which a variable is declared during the first pass of the javascript compilation, which has two passes, compilation and execution. During the compilation pass, the compiler goes through the code looking for formal declaration, that is, var, function and parameters of function. For each of these formal declarations, the compiler will check the current lexical scope, and add this identifier if it isn't already there. Then at the second pass, execution, the compiler will run the code as we are intuitively use to and once it reaches the the identifiers found earlier, will ask if they are left hand side(RHS), or right hand side (LHS). If th...
Post a Comment
Read more