Looking for an explanation of QGIS Edit Widgets

Question

I have noticed "Edit Widgets" under the Quantum GIS and would like to know in detail the use case and usage of this widget.

For any opened vector file, under the Properties -> Fields Tab, for every attribute feature there is a Edit Widget shown. Can someone explain in detail, the the use of these widgets?

If the answer is in form of Tutorial, I'm sure it will help a lot of users like me.

Answer 1

Users can choose from one of the following editing widgets:

• Line edit – a simple edit box
• Classification – displays a combo box with the values used for “unique value” classification (symbology tab)
• Range – allows numeric values within a given range, the widget can be either slider or spin box
• Unique values
  • editable – displays a line edit widget with auto-completion suggesting values already used in the attribute table
  • not editable – displays a combo box with already used values
• File name – adds a file chooser dialog
• Value map – shows a combo box with predefined description/value items
• Enumeration – a combo box with values that can be used within the columns type
• Immutable – read-only
• Hidden – makes the attribute invisible for the user
• Checkbox – a checkbox with customizable representation for both checked and unchecked state
• Text edit – an edit box that allow multiple input lines
• Calendar – a calendar widget to input dates

[Source: http://underdark.wordpress.com/2010/07/28/customized-attribute-editing-in-qgis-1-5/]

Answer 2

The edit widgets are used to control which UI control is used when the edit form (feature form) is shown to the user. These can be used to better control the input from the use, or aid in data collection, e.g Selecting Checkbox will show a tick box to the user for the field in the form.

These two posts cover a simple use case:

How to create a drop down list?

How to have a drop down list for feature editing (attributes) in Quantum GIS?