SiLA Data Types

This section describes how SiLA data types are mapped to Python types.

Basic types

  • Integer: int, a ValueError will be raised for values < -2^63 or > 2^63-1

  • Real: float

  • Boolean: bool

  • String: string, a ValueError will be raised if the length exceeds 2^21

  • Binary: bytes, for values > 2 MB both sides of the communication must support SiLA Binary Transfer (which this SDK does)

  • Date: SilaDateType, a NamedTuple class with the fields date and timezone (date, timezone)

    • Note: Other timezone implementations might also work, as long as they map unambiguously to a UTC offset

  • Time: time, a ValueError will be raised if the tzinfo attribute is None

    • Note: Other timezone implementations might also work, as long as they map unambiguously to a UTC offset

  • Timestamp: datetime, a ValueError will be raised if the tzinfo attribute is None

  • Any: SilaAnyType, a NamedTuple class with the fields type_xml and value (str, Any)

List

The List type is mapped to a Python list.

Constrained

The Constrained type is handled like its base type. When a SiLA Server implemented using this SDK receives a value of a Constrained type as a command parameter, it will validate the value and raise a ValidationError if the value does not satisfy all constraints.

Structure

Structures are mapped implicitly to named tuples. These are currently not supported by the code generator, so no appropriate NamedTuple classes are generated yet. The SDK will interpret plain tuple objects as structures, if it has the proper number and types of items.

Example

A data type Point2D is defined like this:

<DataType>
    <Structure>
        <Element>
            <Identifier>X</Identifier>
            <DisplayName>X</DisplayName>
            <Description>The X coordinate</Description>
            <DataType>
                <Basic>Integer</Basic>
            </DataType>
        </Element>
        <Element>
            <Identifier>Y</Identifier>
            <DisplayName>Y</DisplayName>
            <Description>The Y coordinate</Description>
            <DataType>
                <Basic>Integer</Basic>
            </DataType>
        </Element>
    </Structure>
</DataType>

The implicitly created class is:

from typing import NamedTuple

class Point2D_Struct(NamedTuple):
    X: int
    Y: int

When you receives a Point2D object, you can access the structure elements like this:

>>> point = client.CoordinateFeature.Create2DPoint(1, 2)  # returns Point2D(1, 2)

>>> # tuple indexing
>>> x = point[0]
>>> y = point[1]

>>> # attributes
>>> x = point.X
>>> y = point.Y

>>> # iterable unpacking
>>> x, y = point

When expecting a Structure, the SDK will accept a plain tuple containing two int objects: (1, 2).