Web Part Life Cycle

Simple Webpart Life Cycle (Not UserControl based WebPart).

 

1. OnInit
2. OnLoad
3. LoadViewState 
4. CreateChildControls
5. EnsureChildControls
6. OnPreRender
7. SaveViewState
8. Render
9. RenderContents
10. OnUnload
11. Dispose

Visual Webpart Life Cycle ( UserControl based WebPart).

1. OnInit
2. LoadViewState
3. OnLoad
4. Page_Load
5. OnPreRender
6. SaveViewState
7. Render
8. OnUnload
9. Dispose

There are two way the events are firing.

Initial Load:

Events fired when a web part is initially loaded.

OnInit

OnLoad

EnsureChildControls

CreateChildControls

EnsureChildControls

CreateControlCollection

EnsureChildControls (many)

OnPreRender

EnsureChildControls (many)

SaveViewState

RenderControl

Render

RenderControl

RenderContents

RenderChildren

OnUnload

Dispose

Post-back:

• OnInit
• LoadViewState
• EnsureChildControls
• CreateChildControls
• EnsureChildControls
• CreateControlCollection
• EnsureChildControls (many)
• OnLoad
• btnUpdate_Click
• OnBubbleEvent
• EnsureChildControls
• OnPreRender
• EnsureChildControls (many)
• SaveViewState
• RenderControl
• Render
• RenderControl
• RenderContents
• RenderChildren
• OnUnload
• Dispose

 

OnInit: This method handles initialization of the control.

OnLoad: This event handles the Load event. This is also used for initialize the control but is not intended for loading data or other processing functionality.

LoadViewState: The view state of the web part is populated over here.

CreateChildControls: This is the most popular event in web part life cycle. This creates any child controls. So if you are adding any control to display then you have to write in this method.

EnsureChildControls: This method ensures that CreateChildControls has executed. EnsureChildControls method must be called to prevent null reference exceptions.

SaveViewState: View state of the web part saved.

OnPreRender: This method handles or initiates tasks such as data loading that must complete before the control can render.

Page.PreRenderComplete: The page fires the PreRenderComplete event after all controls have completed their OnPreRender methods.

Render: This method is used to render everything.

RenderContents: Renders the contents of the control only, inside of the outer tags and style properties.

OnUnload: Performs the final cleanup.