Class DeleteStatement

cassandra/cqlengine/statements.py:840–907

a cql delete statement

class DeleteStatement(BaseCQLStatement):
    """ a cql delete statement """

    def __init__(self, table, fields=None, where=None, timestamp=None, conditionals=None, if_exists=False):
        super(DeleteStatement, self).__init__(
            table,
            where=where,
            timestamp=timestamp,
            conditionals=conditionals
        )
        self.fields = []
        if isinstance(fields, str):
            fields = [fields]
        for field in fields or []:
            self.add_field(field)

        self.if_exists = if_exists

    def update_context_id(self, i):
        super(DeleteStatement, self).update_context_id(i)
        for field in self.fields:
            field.set_context_id(self.context_counter)
            self.context_counter += field.get_context_size()
        for t in self.conditionals:
            t.set_context_id(self.context_counter)
            self.context_counter += t.get_context_size()

    def get_context(self):
        ctx = super(DeleteStatement, self).get_context()
        for field in self.fields:
            field.update_context(ctx)
        for clause in self.conditionals:
            clause.update_context(ctx)
        return ctx

    def add_field(self, field):
        if isinstance(field, str):
            field = FieldDeleteClause(field)
        if not isinstance(field, BaseClause):
            raise StatementException("only instances of AssignmentClause can be added to statements")
        field.set_context_id(self.context_counter)
        self.context_counter += field.get_context_size()
        self.fields.append(field)

    def __unicode__(self):
        qs = ['DELETE']
        if self.fields:
            qs += [', '.join(['{0}'.format(f) for f in self.fields])]
        qs += ['FROM', self.table]

        delete_option = []

        if self.timestamp:
            delete_option += ["TIMESTAMP {0}".format(self.timestamp_normalized)]

        if delete_option:
            qs += [" USING {0} ".format(" AND ".join(delete_option))]