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Mixin

Shared request-handler mixin for odin-control.

This module implements a mixin class providing CORS and Server header behaviour used by both API and static route handlers.

Tim Nicholls, STFC Detector Systems Software Group

HandlerMixin

Mixin to apply CORS and Server header behaviour to handlers.

Source code in src/odin_control/http/handlers/mixin.py 
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class HandlerMixin:
    """Mixin to apply CORS and Server header behaviour to handlers."""

    def initialize(self, *args, **kwargs):
        """Initialise handler and set CORS headers if enabled.

        Expects optional ``enable_cors`` and ``cors_origin`` keyword arguments in
        handler URLSpec params.
        """
        enable_cors = kwargs.pop("enable_cors", False)
        cors_origin = kwargs.pop("cors_origin", "*")

        super().initialize(*args, **kwargs)  # type: ignore[misc]

        if enable_cors:
            self.set_header("Access-Control-Allow-Origin", cors_origin)
            self.set_header("Access-Control-Allow-Headers", "x-requested-with,content-type")
            self.set_header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")

    def options(self, *_):
        """Handle CORS preflight OPTIONS requests with no content."""
        self.set_status(204)

    def set_default_headers(self):
        """Set default response headers including an OdinControl Server token.

        This method overrides the base RequestHandler to set the default Server header for all
        responses. The header is set to include name and version of odin-control. If the header is
        already set, e.g. by the base Tornado implementation, append that value to the header.
        """
        server_header_str = f"OdinControl/{__version__}"
        if "Server" in self._headers and not str(self._headers["Server"]).startswith(
            server_header_str
        ):
            server_header_str += f" {self._headers['Server']}"

        self.set_header("Server", server_header_str)

initialize(*args, **kwargs)

Initialise handler and set CORS headers if enabled.

Expects optional enable_cors and cors_origin keyword arguments in handler URLSpec params.

Source code in src/odin_control/http/handlers/mixin.py 
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def initialize(self, *args, **kwargs):
    """Initialise handler and set CORS headers if enabled.

    Expects optional ``enable_cors`` and ``cors_origin`` keyword arguments in
    handler URLSpec params.
    """
    enable_cors = kwargs.pop("enable_cors", False)
    cors_origin = kwargs.pop("cors_origin", "*")

    super().initialize(*args, **kwargs)  # type: ignore[misc]

    if enable_cors:
        self.set_header("Access-Control-Allow-Origin", cors_origin)
        self.set_header("Access-Control-Allow-Headers", "x-requested-with,content-type")
        self.set_header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")

options(*_)

Handle CORS preflight OPTIONS requests with no content.

Source code in src/odin_control/http/handlers/mixin.py 
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def options(self, *_):
    """Handle CORS preflight OPTIONS requests with no content."""
    self.set_status(204)

set_default_headers()

Set default response headers including an OdinControl Server token.

This method overrides the base RequestHandler to set the default Server header for all responses. The header is set to include name and version of odin-control. If the header is already set, e.g. by the base Tornado implementation, append that value to the header.

Source code in src/odin_control/http/handlers/mixin.py 
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def set_default_headers(self):
    """Set default response headers including an OdinControl Server token.

    This method overrides the base RequestHandler to set the default Server header for all
    responses. The header is set to include name and version of odin-control. If the header is
    already set, e.g. by the base Tornado implementation, append that value to the header.
    """
    server_header_str = f"OdinControl/{__version__}"
    if "Server" in self._headers and not str(self._headers["Server"]).startswith(
        server_header_str
    ):
        server_header_str += f" {self._headers['Server']}"

    self.set_header("Server", server_header_str)