CLI Parameter Types
You can use several data types for the CLI options and CLI arguments, and you can add data validation requirements too.
Data conversion
When you declare a CLI parameter with some type Typer will convert the data received in the command line to that data type.
For example:
{ docs_src/parameter_types/index/tutorial001.py hl[4] }
In this example, the value received for the CLI argument NAME
will be treated as str
.
The value for the CLI option --age
will be converted to an int
and --height-meters
will be converted to a float
.
And as female
is a bool
CLI option, Typer will convert it to a "flag" --female
and the counterpart --no-female
.
And here's how it looks like:
$ python main.py --help
// Notice how --age is an INTEGER and --height-meters is a FLOAT
Usage: main.py [OPTIONS] NAME
Arguments:
NAME [required]
Options:
--age INTEGER [default: 20]
--height-meters FLOAT [default: 1.89]
--female / --no-female [default: True]
--help Show this message and exit.
// Call it with CLI parameters
$ python main.py Camila --age 15 --height-meters 1.70 --female
// All the data has the correct Python type
NAME is Camila, of type: class 'str'
--age is 15, of type: class 'int'
--height-meters is 1.7, of type: class 'float'
--female is True, of type: class 'bool'
// And if you pass an incorrect type
$ python main.py Camila --age 15.3
Usage: main.py [OPTIONS] NAME
Try "main.py --help" for help.
Error: Invalid value for '--age': '15.3' is not a valid integer
// Because 15.3 is not an INTEGER (it's a float)
Watch next
See more about specific types and validations in the next sections...
/// info | Technical Details
All the types you will see in the next sections are handled underneath by Click's Parameter Types.
///