Form Action

The form action implements our open-source form validation & transformation library, enabling you to parse, validate and transform complex, hierarchical data.

Getting Started

A form consists of a number of fields. Each field can define one or more validators, which can validate and transform the content of the field. If the form validation is successful, the action will return the validated fields. If not, an error will be thrown. Here's an example form action specification:

type: form
config:
  fields:
    - name: date
      validators:
        - type: IsString
        - type: IsTime
          config:
            format: rfc3339
    - name: count
      validators:
        - type: IsInteger
          config:
            hasMin: true
            min: 0
            hasMax: true
            max: 1000

This action will ensure each item has a date field that contains an RFC-3339 formatted data string and a count field that contains an integer value between 0 and 1000. There are many other validator types available, here's the full list:

• CanBeAnything: Just ensures the field is present, but does not perform any other validation on it.
• IsBoolean: Ensures the field contains a boolean value, i.e. true or false.
• IsBytes: Ensures the field contains a byte array with a given encoding, e.g. hex, base64 or base64-url encoded data.
• IsFloat: Ensures the field contains a float value. Optionally, if hasMin or hasMax is true, the min or max config options define the range of the float value.
• IsHex: Ensures the field contains a hex value. If convert is true, the value will be converted to a byte array.
• IsIn: Ensures the field contains one of the specified choices.
• IsInteger: Ensure the filed contains an integer value. Optionally, if hasMin or hasMax is true, the min or max config options define the range of the integer value.
• IsList: Ensures the field contains a list of values. Optionally, a list of validators will be applied to each list element.
• IsNotIn: Like IsIn, but ensures the value of the field is not in the given choices.
• IsOptional: Will skip the other validators if the field is undefined, making it optional.
• IsString: Ensures the field contains a string value. Optionally, minLength and maxLength specify the minimum and maximum length of the string.
• IsStringList: Ensures the field contains a list of strings. Optionally, a list of validators will be applied to each list element.
• IsStringMap: Ensures the field contains a string-based hash map / dictionary. Optionally, a form can be specified that will be used to validate the value.
• IsTime: Ensures the field contains a datetime/time object in the given format, either rfc3339, rfc3339-date, unix, unix-nano or unix-milli. If raw is true the string will not be converted to a Time object. If toUTC is true, the resulting Time object will be converted to UTC.
• IsUUID: Ensures the field contains a UUID value.
• MatchesRegex: Ensures the field matches the given regular expression. Assumes that the field contains a string value, which should be validated before using the IsString validator.
• Or: Ensures the field contains one of several possible values as specified by a list of options, which in turn contain a list of validators. Will stop at the first option that successfully validates the value.
• Switch: Validates the field against a list of validators defined in a cases string map, where the chosen case depends on the value of another field whose name is given by key.

Actions Within Forms

In addition, the form mechanism supports all other actions as well through the IsAction validator, which takes an action specification as configuration. Example validator:

type: IsAction
config:
  type: pseudonymize
  config:
    method: merengue

This performs a pseudonymization of the value using the merengue method. Parameters of embedded actions are managed automatically by the form action.