Validation types#

By default, the compiler validates the types of the attributes of a service instance. For certain types, type checking is done at the API level, prior to compilation. This provides a more interactive feedback to the operator since validation is performed before firing up the compile process. Type validation is done at the API level for the following types:

  • Primitive types: int, number, string, bool, dict and list.

  • Certain types defined via the typedef statement.

The std module already defines many commonly used types for which validation is performed at the API level (e.g., ip, url, date, …). The section below defines for which typedef statement validation is done at the API level.

Supported forms#



typedef <attr> as <type> matching self in <enumeration>


typedef colour as string matching self in ["red", "green", "blue"]
typedef bundle_size as number matching self in [1, 10, 100]

Regular expressions#


typedef <attr> as <type> matching <pattern>


typedef lowercase as string matching /^[a-z]+$/

Number constraints#


typedef <attr> as <type> matching self <cmp> <value> [(or | and) <comparison_2> ...]
typedef <attr> as <type> matching <value> <cmp> self [(or | and) <comparison_2> ...]


  • <cmp> is one of <, <=, >, >=

  • <value> is any number


typedef port_number as int matching self > 1023 and self <= 65535


The std::validate_type() function allows for finer grained type definition.

These three forms are supported:

typedef <attr> as <type> matching std::validate_type(<parameters>)
typedef <attr> as <type> matching std::validate_type(<parameters>) == true
typedef <attr> as <type> matching true == std::validate_type(<parameters>)


typedef my_type as int matching true == std::validate_type("pydantic.conint", self, {"gt": 0, "lt": 10})