Validaterl

Validaterl is a simple Erlang library for validating (input) data.

Validation Primitives

Using records defined in validaterl/include/validaterl.hrl one can check individual values against validators.

For example:

>validaterl:validate(1, #range{ to=10 })
true>validaterl:validate(1, #range{ to=0 })
greater

Also, if the second argument is not a validator, it will be matched against the first argument:

>validaterl:validate(1, 1).
true>validaterl:validate(1, 2).
lesser>validaterl:validate(1, 0).
greater

Custom Validators

One can define custom validators using this layout:

-record(my_validator, {
'$validator'=funmymodule:myvalidator/2,
... %% rest of arguments
}).

Validation Sheets

Instead of running individual validations, you can define so called "validation sheets" and test them using validaterl:validate/1.

Validation sheet is a list of validations in the following format:

{Name::any(), Value::any(), Spec::spec()}

For example:

[
{'user.name', Username, #length{ is=#range{ from=3, to=16 } }},
{'user.email', Email, #length{ is=#range { from=3, to=255 } }},
{'user.age', Age, #numericality{ allow_string=true }}
]

Just as an example, if you try to put a string with a non-numeric value into Age, you'll get this:

[{'user.age',"wrong",
#numericality{'$validator'= #Fun<validaterl.validate.2>,
allow_undefined=false,allow_null=false,
allow_string=true,allow_empty=false,allow_rest=false,
allow_float=true,default=0},
number_expected}]