render.py 文件源码

def _render_check_constraint(constraint, autogen_context):
    rendered = _user_defined_render("check", constraint, autogen_context)
    if rendered is not False:
        return rendered

    # detect the constraint being part of
    # a parent type which is probably in the Table already.
    # ideally SQLAlchemy would give us more of a first class
    # way to detect this.
    if constraint._create_rule and \
        hasattr(constraint._create_rule, 'target') and \
        isinstance(constraint._create_rule.target,
                   sqltypes.TypeEngine):
        return None
    opts = []
    if constraint.name:
        opts.append(
            (
                "name",
                repr(
                    _render_gen_name(
                        autogen_context, constraint.name))
            )
        )
    return "%(prefix)sCheckConstraint(%(sqltext)s%(opts)s)" % {
        "prefix": _sqlalchemy_autogenerate_prefix(autogen_context),
        "opts": ", " + (", ".join("%s=%s" % (k, v)
                                  for k, v in opts)) if opts else "",
        "sqltext": _render_potential_expr(
            constraint.sqltext, autogen_context, wrap_in_text=False)
    }