As we know react works on virtual Dom, not real Dom. When state or props changed،،،،، this change is in the virtual Dom. Can we consider when the call setstate() method this change applies on the real Dom?
the setState will trigger a new render on the virtual DOM, which will use its diffing algorithm to check what has changed in the virtual DOM from the last snapshot to the current one.
After that, the virtual DOM will send a "package" with all the needed changes to make.
Finally, the real DOM will update the users' screen.
Related
I'm new to React, and I'm trying to figure out some basics. In other template engines such as EJS or Jade, you are able to pass in a context variable when you are rendering the view file in your routes/controller file. However, I have not found any way to do this with React/jsx. I should note that I am working with Express.
I am actually uncertain if jsx is a view engine, or if React somehow was one built in. In either case, I do not know how to pass context from the server to the view file.
For example, if I wanted to load profile information (that is stored on the server/backend), how would I pass that to my front end jsx view file in React/jsx?
that's simple. There is a mess in MVC terminology, but I think it would be okay to say that React component is not just the "View", but "View + Controller".
As a direct analogy to the templating engines, component's render() function is your template. And component.state (which is local to the component) and component.props (arguments received from the upper component) both can be used as a "context".
If you want some really close analogy to the React component in the conservative part of the JS world, it's Backbone's View (which is again the view + controller if we use original MVC terminology; as I told - it's a mess). Conceptually, it's the same thing. JSX is used in render() instead of EJS (or whatever), that's it.
Btw, React's context concept is something different. Think of it as
props which are visible to the whole component subtree starting from
the component where the context is exposed.
For example, if I wanted to load profile information (that is stored on the server/backend), how would I pass that to my front end jsx view file in React/jsx?
In the simplest case, you create the top-level React component, which would load the stuff you need on mount (componentWillMount()), put it to its local state when you'll receive the response from server (this.setState(...)), and pass elements of its state (this.state) down to the subcomponents as props (<List items={ this.state.items } />) in its render() function.
Whenever state is modified with this.setState(...), the whole component subtree will render again. That's how it works. In the simplest case.
I have some custom controls that I want to include in Xpages, but I don't want them to be visible to the user or to take up space on the screen, as it is throwing my alignment off. I have looked at the properties rendered, loaded, and visible, but I don't really understand them and they don't seem to do what I want, which is to include some functionality but not change the layout.
I am sure there is a way to do this, but I can't figure it out.
Loaded means it won't be added to the component tree and only affects server-side functionality. Because it's not in the component tree (the server-side map of the page) it can't be passed to the browser or processed during partial refreshes. Rendered and visible are the same and mean they're in the component tree, so server-side processing can interact with them, but no HTML is passed to the browser for them. So you can't interact with them via CSJS. If you want it passed to the browser, available for CSJS but not visible to the user, you'll need to set the style as display:none. Another option is to put that style in a theme and allocate the themeId you choose to your custom control.
I'm having a strange issue with Yii and a theme. I set it in config/main.php like:
'theme'=>'themeName',
as usual. But when I try to render a view, it is rendered as is, without any layout, as if I called:
$this->renderPartial
I double check that I don't call for renderPartial, the themes seem to be equal to all the others theme I've done. What can be this issue about?
Thank's for any help, I'm going out of mind on this...
Here is the structure and syntax that you should have to check
-yiiroot
-!-!protected
-!-!-!controllers
-!-!-!-!TestController.php
-!-!themes
-!-!-!themeName (it was the one that you have set on config file)
-!-!-!-!views
-!-!-!-!-!layouts
-!-!-!-!-!-!main.php // It would be default what if public $layout has not been overwriten or the layout file which has been set was not found
-!-!-!-!-!test
-!-!-!-!-!-!viewName.php
On controller TestController
public $layout is main as default or is overwritten there
in actionIndex you set $this->render('viewName');
If you rendered your page by method renderPartial() directly in controller, you would not get the layout template for sure
render() is commonly used to render a view that corresponds to what a
user sees as a "page" in your application. It first renders the view
you have specified and then renders the layout for the current
controller action (if applicable), placing the result of the first
render into the layout. It then performs output processing (which at
this time means automatically inserting any necessary tags
and updating dynamic content) and finally outputs the result.
renderPartial() is commonly used to render a "piece" of a page. The
main difference from render() is that this method does not place the
results of the render in a layout. By default it also does not perform
output processing, but you can override this behavior using the
$processOutput parameter.
renderFile() is a low-level method that does the grunt work of
rendering: it extracts the data variables in the current scope and
then runs the view code. The other two methods internally call this
one, but you should practically never need to call it yourself. If you
do, keep in mind that you need to pass in a file path (not a view
path).
Reference: Yii difference between rendering functions
I'm trying to send a parameter from Portlet doView function to portal_normal.vm
Is it possible? How can I send and receive it?
Sorry, but I can't see the way to do through request.
In doView I wrote
HttpServletRequest httpRequest = PortalUtil.getOriginalServletRequest(PortalUtil.getHttpServletRequest(renderRequest));
httpRequest.setAttribute("hola", "hola");
And in the portal normal I tried with:
#set ($holas =$request.get('attributes').get('hola'))
#set ($holas2 = $request.getSession().getAttribute("hola"))
$holas
$holas2
but Velocity only shows $holas $holas2
This sounds like an overly specific plan to display some information outside of the portlet - but also well outside the portlet spec. Is it possible? Yes. Does it have limitations? Yes.
I didn't try it, but I'd argue that you don't have any guarantee that all render phases of all portlets have been finished before portal_normal.vm starts to be evaluated. Technically it's only necessary to have them finished once they are actually about to render. Render is not allowed to change any state - and you're implying that in your case it might do - because on render something else will be displayed.
It might make sense to rather assume that your theme has some DOM element that is available on the page. Then render some javascript that manipulates this DOM element. The dependency on the theme is the same, but you could also fall back to some default rendering in case you can't find the DOM element.
Alternatively, if you insist on your mode of operation. you might try to go through the servlet-session (portlet session won't help) as you have access to the HttpServletRequest from portal_normal.vm. Be warned though: Access to HttpServletRequest is nonstandard and not really portal-thinking
I have an issue with the dynamic content control in ExtLib. Every time I compile my xpage the dynamic content control flips out if I do not reload the page. I need a way to control this, like an onerror event on the control.
this is wahat's happening
I open my webpage, the dynamic content control works fine
I do some changes to my xpages and build (webpage still open)
I click a link on my webpage to reload the content in the dynamic content control.
the webpage flips out and starts to reload constantly using a partial refresh url.
I use various ways to update this control. sometimes it is through a csjs link and somtimes it is per interval using XSP.partialRefreshGet() so I guess I need a way to know if the dynamic content control is available before calling it, or let the control notify me somehow that is is not available
any idea?
Thanks
Thomas
When you change an XPage you must do a manual full reload of that page in any browser. Executing any call from the stale page will not work.