anusha(salesforce developer)

Friday 29 July 2016

How To Use <apex:commandLink> In Visualforce Page?

<apex:commandLink>:
This tag creates a link that helps to execute an action defined in a controller.  Normally action can be executed using buttons but in situations where you need links to be placed on your page we can use this tag. Similar to the command button tag action method, this links also transfers control to a different and then either refreshes the current page, or navigates to a different page based on the PageReference variable that is returned by the action. An < apex:commandLink > component must always be a child of an < apex:form > component.

To add query string parameters to an < apex:commandLink >, specify them in the associated action method attribute.

Syntax:
<apex:commandLink action="{!save}" value="Save" id="theCommandLink"/> 


This tag supports following attributes:

Attribute
Description
accesskey
The keyboard access key that puts the command link in focus. When the command link is in focus, pressing the Enter key is equivalent to clicking the link.
action
The action method invoked by the AJAX request to the server. Use merge-field syntax to reference the method. For example, action="{!save}" references the save() method in the controller. If an action is not specified, the page simply refreshes. Note that command links associated with the save, edit, or delete actions in a standard controller are not rendered if the user does not have the appropriate permissions. Likewise if no particular record is associated with a page, command links associated with the edit and delete actions are also not rendered.
charset
The character set used to encode the specified URL. If not specified, this value defaults to ISO-8859-1.
coords
The position and shape of the hot spot on the screen used for the command link (for use in client-side image maps). The number and order of comma-separated values depends on the shape being defined. For example, to define a rectangle, use coords="left-x, top-y, right-x, bottom-y". To define a circle, use coords="center-x, center-y, radius". To define a polygon, use coords="x1, y1, x2, y2, ..., xN, yN", where x1 = nN and y1 = yN. Coordinates can be expressed in pixels or percentages, and represent the distance from the top-left corner of the image that is mapped. See also the shape attribute.
dir
The direction in which the generated HTML component should be read. Possible values include "RTL" (right to left) or "LTR" (left to right).
hreflang
The base language for the resource referenced by this command link, for example, "en" or "en-US".
id
An identifier that allows the commandLink component to be referenced by other components in the page.
immediate
A Boolean value that specifies whether the action associated with this component should happen immediately, without processing any validation rules associated with the fields on the page. If set to true, the action happens immediately and validation rules are skipped. If not specified, this value defaults to false.
lang
The base language for the generated HTML output, for example, "en" or "en-US".
onblur
The JavaScript invoked if the onblur event occurs that is, if the focus moves off of the command link.
onclick
The JavaScript invoked if the onclick event occurs that is, if the user clicks the command link.
oncomplete
The JavaScript invoked when the result of an AJAX update request completes on the client.
ondblclick
The JavaScript invoked if the ondblclick event occurs that is, if the user clicks the command link twice.
onfocus
The JavaScript invoked if the onfocus event occurs that is, if the focus is on the command link.
onkeydown
The JavaScript invoked if the onkeydown event occurs that is, if the user presses a keyboard key.
onkeypress
The JavaScript invoked if the onkeypress event occurs that is, if the user presses or holds down a keyboard key.
onkeyup
The JavaScript invoked if the onkeyup event occurs that is, if the user releases a keyboard key.
onmousedown
The JavaScript invoked if the onmousedown event occurs that is, if the user clicks a mouse button.
onmousemove
The JavaScript invoked if the onmousemove event occurs that is, if the user moves the mouse pointer.
onmouseout
The JavaScript invoked if the onmouseout event occurs that is, if the user moves the mouse pointer away from the command link.
onmouseover
The JavaScript invoked if the onmouseover event occurs that is, if the user moves the mouse pointer over the command link.
onmouseup
The JavaScript invoked if the onmouseup event occurs that is, if the user releases the mouse button.
rel
The relationship from the current document to the URL specified by this command link. The value of this attribute is a space-separated list of link types. 
rendered
A Boolean value that specifies whether the component is rendered on the page. If not specified, this value defaults to true.
reRender
The ID of one or more components that are redrawn when the result of an AJAX update request returns to the client. This value can be a single ID, a comma-separated list of IDs, or a merge field expression for a list or collection of IDs.
rev
The reverse link from the URL specified by this command link to the current document. The value of this attribute is a space-separated list of link types. 
shape
The shape of the hot spot in client-side image maps. Valid values are default, circle, rect, and poly. See also the coords attribute.
status
The ID of an associated component that displays the status of an AJAX update request. See the actionStatus component.
style
The style used to display the commandLink component, used primarily for adding inline CSS styles.
styleClass
The style class used to display the commandLink component, used primarily to designate which CSS styles are applied when using an external CSS stylesheet.
tabindex
The order in which this link is selected compared to other page components when a user presses the Tab key repeatedly. This value must be an integer between 0 and 32767, with component 0 being the first component that is selected when a user presses the Tab key.
target
The name of the frame where the resource retrieved by this command link should be displayed. Possible values for this attribute include "_blank", "_parent", "_self", and "_top". You can also specify your own target names by assigning a value to the name attribute of a desired destination.
timeout
The amount of time (in milliseconds) before an AJAX update request should time out.
title
The text to display as a tooltip when the user's mouse pointer hovers over this component.
type
The MIME content type of the resource designated by this command link. Possible values for this attribute include "text/html", "image/png", "image/gif", "video/mpeg", "text/css", and "audio/basic". 
value
The text that is displayed as the commandLink label. Note that you can also specify text or an image to display as the command link by embedding content in the body of the commandLink tag. If both the value attribute and embedded content are included, they are displayed together.

Visualforce Example:


<apex:page standardController="Account">
    <apex:form >
        <apex:pageBlock title="My Content" mode="edit">
            <apex:pageBlockSection title="My Content Section" columns="1">
                   <apex:inputField value="{!account.name}"/>
                   <apex:inputField value="{!account.site}"/>
              </apex:pageBlockSection>
                      <apex:pageBlockButtons >
                           <apex:commandlink action="{!save}" value="Save"/>
                     </apex:pageBlockButtons>
              </apex:pageBlock>
    </apex:form>
</apex:page>




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