Snippets by sago

Currency Fields with newforms

The newforms package allows you to simply add new field types to your forms. This snippet shows the addition of a new type of field, to make sure the user enters sensible currency values (either with no decimal, or two-decimal places), and a custom widget to make sure that the value is displayed correctly when the user sees the form. The CurrencyInput widget simply tries to display the current value in floating point 2-decimal places format (and gives up if it can't). The CurrencyField makes sure that the input value matches a regular expression, and when it is asked to clean the value it converts it to a float. The regex here limits the amount to 99,999.99 or less. This is within the bounds of accuracy of python's float value. If you want to use truly huge values for the amount, then you'll face problems with the floating point not being able to represent the values you enter, and so the conversion to floating point in the field will fail. In this case it would be better to use python longs, and used a fixed point interpretation.