In MVC application you have encounter many MVC attributes like HandleError and many more. These attributes servers one particular task so that you do not have to re-write the code for for it.
If you want to write your attribute in controller, then how can we do that?
MVC provides one class named ActionMethodSelectorAttribute, which can help us to create our own custom attribute. Let's create our own attrubite "AjaxMethodAttribute". This attribute tests the Ajax request. If the request from Ajax method came, allow the action to execute. The request other than the Ajax should be neglected.
We will create the class named AjaxMethodAttribute inherited from ActionMethodSelectorAttribute. The class ActionMethodSelectorAttribute has one override method IsValidForRequest which has to be implemented. Here is our implementation. public class AjaxMethodAttribute : ActionMethodSelectorAttribute
{
///
/// Implement IsValidForRequest method as per your need.
///
public override bool IsValidForRequest(ControllerContext controllerContext, MethodInfo methodInfo)
{
// Check request of Ajax.
return controllerContext.HttpContext.Request.IsAjaxRequest();
}
}
You can now have our custom attribute ready for use. Let's try it.
[AjaxMethodAttribute] public ActionResult AjaxRequest() { ViewData["AjaxCall"] = "Call from Aajx Request"; return View("AjaxRequest"); }
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Whenever the user for a action / method which does not exists in any controller, the framework shows the error message. How to handle it?
Each controller has one override method named "HandleUnknownAction". You can use it to handle the unknown request. The method accept one parameter actionname.
/// Method to process unknown action request. /// Unknwoan action name
In MVC your can return the View which will be view of the same Controller or any other existing controllers. If the view does not exist the framework search the view in Views/Shared folder.
Now, suppose you have to call the view stored in some folder MyViews under the Views folder. There is no controller with name MyViews. How to call this view then?
Here is the solution:
return View("../MyViews/TestView");
You can call this view using relative path as shown above.
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In this blog we will learn how to manipulate the page contents using jQuery.
The topics we will learn in today's blog are:
Overview of content manipulation:
Creating, setting, and getting content
Manipulating attributes
Inserting Content
Wrapping, replacing, removing content
Working with CSS information
Working with CSS classes
Working with CSS positioning
Working with CSS sizing information
Overview of content manipulation:
Once you’ve used selectors and filters to retrieve web page content, you usually want to do something with it
Sometimes you want to create new content to dynamically add into the page
jQuery has functions for creating, copying, deleting, and moving content around, as well as wrapping page content in other content
jQuery provides cross-browser support for working with CSS, including positioning and sizing information
Creating, setting, and getting content:
To create new HTML content, you simply pass a string containing new HTML to the $() function:
Var newHeader = $(“My new header”);
Var myStr = “My new header”;
Var newHeader = $(myStr);
In addition to this method, you can use the html() and text() methods to get and set content on
Function
Purpose
html()
Returns the HTML content of the first matched element
html(newcontent)
Sets the HTML content of every matched element
text()
Returns the text content of the first matched element
text(newtext)
Sets the text content for all matched elements
Manipulating attributes:
To inspect or change the value of attribute on elements, use jQuery’s attr functions
Function
Purpose
attr(name)
Accesses property on the first matched element. This method makes it easy to retrieve a property value from the first matched element. If the element does not have an attribute with such a name, undefined is returned
attr(properties)
Set a series of attributes on all matched element using an object notation syntax. This is the best used for setting large numbers of properties at once
$(“img”).attr({ src: “/images/hat.gif”, title: “jQuery”, alt: “jQuery Logo”});
attr(key, value)
Sets a single property to a value on all matched elements
attr(key, fn)
Sets a single property to a computed value, on all matched elements. Instead of supplying a string value, a function is provided that computes the value of the attribute
removeAttr(name)
Removes the named attribute from all matched elements
Inserting Content:
JQuery provides several functions for inserting content into the document, both before and after existing page elements
Function
Purpose
append(content)
Appends content to the inside of every matched element
appendTo(selector)
Appends all of the matched elements to another, specified, set of elements
prepend(content)
Prepends content to the inside of every matched element
prependTo(selector)
Prepends all the matched elements to another, specified, set of elements
after(content)
Inserts content after each of the matched elements
before(content)
Inserts content before each of the matched elements
insertAfter(selector)
Inserts all of the matched elements after another, specified, set of elements
insertBefore(selector)
Inserts all of the matched elements before another, specified, set of elements
Wrapping, replacing, removing content:
jQuery can wrap existing content in the page, replace content, copy content, and remove it
Function
Purpose
wrap(html)
Wraps each matched element with the specified HTML content
wrap(element)
Wraps each matched element with the specified element
wrapAll(html)
Wraps all the elements in the matched set with the specified HTML content
wrapAll(element)
Wraps all the elements in the matched set into a single wrapper element
wrapInner(html)
Wraps the inner child contents of each matched element (including text nodes) with an HTML structure
wrapInner(element)
Wraps the inner child contents of each matched element (including text nodes) with a DOM structure
replaceWith(content)
Replaces all matched elements with the specified HTML or DOM elements
replaceAll(selector)
Replaces the elements matched by the specified selector with the matched elements
empty()
Removes all child nodes from the set of matched elements
remove()
Removes all matched elements from the DOM
clone()
Clone matched DOM elements and selects the clones
clone(bool)
Clone matched DOM elements, and all their event handlers, and select the clones
Working with CSS information:
jQuery’s CSS functions provide easy, cross-browser access for setting properties and working with positioning and sizing information
The css() function allows you to retrieve and set CSS styles for a set of matched elements
Filter
Purpose
css(name)
Returns the value for the named CSS property for the first matched element
css(properties)
Sets the CSS properties of every matched element using an object-notation syntax:
var cssObj = {
‘background-color’ : ‘#ddd’,
‘font-weight’ : ‘ ‘
‘color’ : ‘rgb(0, 40, 244)’ }
$(this).css(cssObj);
css(property, value)
Sets a single style property to a value on all matched elements. If a number is provided, it is automatically converted into a pixel value, with the following exception: z-index, font-weight, opacity, zoom, and line-height
Working with CSS classes:
jQuery provides a set of functions for working with CSS classes on page elements
Classes can be easily added, removed, toggled, and detected
CSS Functions
Purpose
addClass(class)
Adds the specified class(es) to each of matched elements
hasClass(class)
Returns true if the specified class is present on at least one of the set of matched elements
removeClass(class)
Removes all the specified class(es) from the set of matched elements
toggleClass(class)
Adds the specified class if it is not present, removes the specified class if it is present
toggleClass(class, switch)
Adds the specified class if the switch is true, removed the specified class if the switch is false
Working with CSS positioning:
The CSS positioning functions provide cross-browser support for figuring out the positions of elements
CSS Functions
Purpose
offset()
Gets the current offset of the first matched element, in pixels, relative to the document
offsetParent()
Returns a jQuery collection with the positioned parent of the first matched element
position()
Gets the top and left position of an element relative to its offset parent
scrollTop()
Gets the scroll top offset of the first matched element
scrollTop(val)
Sets the scroll top offset to the given value on all matched elements
scrollLeft()
Gets the scroll left offset of the first matched element
scrollLeft(val)
Sets the scroll left offset to the given value on all matched elements
Working with CSS sizing information:
To retrieve cross-browser sizing information for elements, use the jQuery size-related CSS function
CSS Functions
Purpose
height()
Gets the current computed, pixel, height of the first matched element
height(val)
Sets the CSS height of every matched element
width()
Gets the current computed, pixel, width of the first matched element
width(val)
Sets the CSS width of every matched element
innerHeight()
Gets the inner height (excluding the border and including the padding) for the first matched element
innerWidth()
Gets the inner width (excluding the border and including the padding) for the first matched element
outerHeight(margin)
Gets the outer height (includes the border and padding by default) for the first matched element. If the margin argument is true, then the margin values are also included
outerwidth(margin)
Gets the outer width (includes the border and padding by default) for the first matched element. If the margin argument is true, then the margin values are also included
In the next blog we will learn Working with events using jQuery.
In the last blog you saw the jQuery overview.
In this blog we will learn:
Overview of Selectors and Filters
Using basic jQuery selectors
Using filters
Using basic jQuery filters
Attribute filters
Content and Visibility filters
Child filters
Form selectors
Traversing Document Information
jQuery statement chaining
Overview of Selectors and Filters:
jQuery selectors and filters retrieve contents from the documents so it can be manipulated using other functions
-jQuery selectors return an array of objects that match the selection criteria
-jQuery filters operates on a selectors to further refine the results array that the selector returns
This array is not a set of DOM elements
It is a collection of jQuery objects that provide a large number of predefined functions for further operating on the objects
Using basic jQuery selectors
CSS-style selectors and filters are based on familiar CSS syntax, and work pretty much the same way as CSS does
The CSS selectors listed here correspond directly to their CSS counterpart s
Selectors
Purpose
tagname
Finds all elements that are named tagname
#identifier
Finds all elements with ID of identifier
.className
Finds all elements that have class attribute with the value of className
tag.className
Get elements of type tag that have a class attribute with the value of className
tag#id.className
Retrieves the tag element that has an ID of id and a class attribute with the value of className
*
Finds all of the elements on the page
The hierarchy and combination selectors allow you to get a little more advanced in selecting page content
You can select elements based on hierarchical relationships or on a series of comman criteria
Selector
Purpose
selector, selector
Finds all of the specified selectors
.class1.class2
Finds all elements with both .class1 and .class2 applied
Parent>child
Finds all child elements that are direct children of elements of type parent
Ancestor descendant
Finds all descendant elements that are contained within elements of type ancestor
Prev + next
Finds all next elements that are next to prev element
Prev ~ siblings
Finds all sibling elements that come after prev and match the siblings selector
Using filters
Filters work with selectors to provide even more fine-grained control over how elements are selected in the document
jQuery filters fall into six different categories
Basic: Provides basic filtering, like getting the first, last, and even- and odd-numbered items in a returned set
Content:Filters a set of elements based on the content, like whether an element contains a particular string
Visibility: Filters a set of elements using the visibility setting of each element as a test
Attribute: Examines a given attribute on an element to determine whether it should be filtered out
Child: Selects elements based upon their relationship with their parent element
Form: Provides specialized filters that operate on form elements
Using basic jQuery filters:
You can refine a selector by including elements that match certain conditions, like position or index
Filter
Purpose
:first
Selects only the first instance of the selector’s returned set
:last
Selects only the last instance of the selector’s returned set
:even
Selects only even-numbered elements in the selector’s returned set
:odd
Selects only odd-numbered elements in the selector’s returned set
:eq(n)
Filters out elements that are not positioned at the given index
:gt(n)
Includes elements that are past the given index
:lt(n)
Includes elements that are before the given index
:header
Selects all header elements (H1, H2, H3, etc)
:animated
Selects all elements that are currently being animated in some way
:not(selector)
Includes elements that do not match the given selector
Attribute filters:
You can filter the results of a selector statement based on attribute content
Filter
Purpose
[attribute]
Includes elements in the result set if they have the specified attribute
[attribute=value]
Includes elements in the result set if they have the specified attribute and it has the given value
[attribute!=value]
Includes elements in the result set only if they have the specified attribute and it doesn’t have the given value
[attribute^=value]
Includes elements that have the specified attribute and it starts with the specified value
[attribute$=value]
Includes elements that have the specified attribute and it ends with the specified value
[attribute*=value]
Includes elements that have the specified attribute and it contains the specified value
[attrFilter1][attrFilterN]
Includes elements that match all of the specified attribute filters
Content and Visibility filters:
You can examine the content of selected elements or their visibility property to determine whether they should be included or excluded from the final set
Content filter
Purpose
:contains(text)
Filters the selection to only include elements that contain the text string
:empty
Filters the selection to only include empty elements
:has(selector)
Matches elements that contain at least one element that has the specified selector
:parent
Matches all elements that are parents (i.e. they contain at least one other element, including text)
Visibility filter
Purpose
:visible
Filters the selection to only include visible elements
:hidden
Filters the selection to only include hidden elements
Child filters:
You can refine a selector by examining the relationship each element has with its parent element
