Source code for squabble.rules.disallow_rename_enum_value

import pglast

import squabble.rule
from squabble.message import Message
from squabble.rules import BaseRule


class DisallowRenameEnumValue(BaseRule):
    """
    Prevent renaming existing enum value.

    Configuration:

    ::

        { "DisallowChangeEnumValue": {} }
    """

    class RenameNotAllowed(Message):
        """
        Renaming an existing enum value may not be backwards compatible
        with code that is live in production, and may cause errors
        (either from the database or application) if the old enum
        value is read or written.
        """
        CODE = 1000
        TEMPLATE = 'cannot rename existing enum value "{value}"'

    def enable(self, ctx, _config):
        ctx.register('AlterEnumStmt', self._check_enum())

    @squabble.rule.node_visitor
    def _check_enum(self, ctx, node):
        """
        Node is an 'AlterEnumStmt' value

        {
            'AlterEnumStmt': {
                'newVal': 'bar',
                'oldVal': 'foo',   # present if we're renaming
            }
        }
        """

        # Nothing to do if this isn't a rename
        if node.oldVal == pglast.Missing:
            return

        renamed = node.oldVal.value

        ctx.report(self.RenameNotAllowed(value=renamed))