Python django.db.models.constants.LOOKUP_SEP.join() Examples

def trim_joins(self, targets, joins, path):
        """
        The 'target' parameter is the final field being joined to, 'joins'
        is the full list of join aliases. The 'path' contain the PathInfos
        used to create the joins.

        Returns the final target field and table alias and the new active
        joins.

        We will always trim any direct join if we have the target column
        available already in the previous table. Reverse joins can't be
        trimmed as we don't know if there is anything on the other side of
        the join.
        """
        joins = joins[:]
        for pos, info in enumerate(reversed(path)):
            if len(joins) == 1 or not info.direct:
                break
            join_targets = set(t.column for t in info.join_field.foreign_related_fields)
            cur_targets = set(t.column for t in targets)
            if not cur_targets.issubset(join_targets):
                break
            targets = tuple(r[0] for r in info.join_field.related_fields if r[1].column in cur_targets)
            self.unref_alias(joins.pop())
        return targets, joins[-1], joins 

def unquote(s):
    """Undo the effects of quote(). Based heavily on urllib.parse.unquote()."""
    mychr = chr
    myatoi = int
    list = s.split('_')
    res = [list[0]]
    myappend = res.append
    del list[0]
    for item in list:
        if item[1:2]:
            try:
                myappend(mychr(myatoi(item[:2], 16)) + item[2:])
            except ValueError:
                myappend('_' + item)
        else:
            myappend('_' + item)
    return "".join(res) 

def add_q(self, q_object):
        """
        A preprocessor for the internal _add_q(). Responsible for
        splitting the given q_object into where and having parts and
        setting up some internal variables.
        """
        if not self.need_having(q_object):
            where_part, having_parts = q_object, []
        else:
            where_part, having_parts = self.split_having_parts(
                q_object.clone(), q_object.negated)
        # For join promotion this case is doing an AND for the added q_object
        # and existing conditions. So, any existing inner join forces the join
        # type to remain inner. Existing outer joins can however be demoted.
        # (Consider case where rel_a is LOUTER and rel_a__col=1 is added - if
        # rel_a doesn't produce any rows, then the whole condition must fail.
        # So, demotion is OK.
        existing_inner = set(
            (a for a in self.alias_map if self.alias_map[a].join_type == INNER))
        clause, require_inner = self._add_q(where_part, self.used_aliases)
        self.where.add(clause, AND)
        for hp in having_parts:
            clause, _ = self._add_q(hp, self.used_aliases)
            self.having.add(clause, AND)
        self.demote_joins(existing_inner) 

def add_q(self, q_object):
        """
        A preprocessor for the internal _add_q(). Responsible for doing final
        join promotion.
        """
        # For join promotion this case is doing an AND for the added q_object
        # and existing conditions. So, any existing inner join forces the join
        # type to remain inner. Existing outer joins can however be demoted.
        # (Consider case where rel_a is LOUTER and rel_a__col=1 is added - if
        # rel_a doesn't produce any rows, then the whole condition must fail.
        # So, demotion is OK.
        existing_inner = {a for a in self.alias_map if self.alias_map[a].join_type == INNER}
        clause, _ = self._add_q(q_object, self.used_aliases)
        if clause:
            self.where.add(clause, AND)
        self.demote_joins(existing_inner) 

def message_user(self, request, message, level=messages.INFO, extra_tags='',
                     fail_silently=False):
        """
        Send a message to the user. The default implementation
        posts a message using the django.contrib.messages backend.

        Exposes almost the same API as messages.add_message(), but accepts the
        positional arguments in a different order to maintain backwards
        compatibility. For convenience, it accepts the `level` argument as
        a string rather than the usual level number.
        """
        if not isinstance(level, int):
            # attempt to get the level if passed a string
            try:
                level = getattr(messages.constants, level.upper())
            except AttributeError:
                levels = messages.constants.DEFAULT_TAGS.values()
                levels_repr = ', '.join('`%s`' % l for l in levels)
                raise ValueError(
                    'Bad message level string: `%s`. Possible values are: %s'
                    % (level, levels_repr)
                )

        messages.add_message(request, level, message, extra_tags=extra_tags, fail_silently=fail_silently) 

def demote_joins(self, aliases):
        """
        Change join type from LOUTER to INNER for all joins in aliases.

        Similarly to promote_joins(), this method must ensure no join chains
        containing first an outer, then an inner join are generated. If we
        are demoting b->c join in chain a LOUTER b LOUTER c then we must
        demote a->b automatically, or otherwise the demotion of b->c doesn't
        actually change anything in the query results. .
        """
        aliases = list(aliases)
        while aliases:
            alias = aliases.pop(0)
            if self.alias_map[alias].join_type == LOUTER:
                self.alias_map[alias] = self.alias_map[alias].demote()
                parent_alias = self.alias_map[alias].parent_alias
                if self.alias_map[parent_alias].join_type == INNER:
                    aliases.append(parent_alias) 

def unquote(s):
    """
    Undo the effects of quote(). Based heavily on urllib.unquote().
    """
    mychr = chr
    myatoi = int
    list = s.split('_')
    res = [list[0]]
    myappend = res.append
    del list[0]
    for item in list:
        if item[1:2]:
            try:
                myappend(mychr(myatoi(item[:2], 16)) + item[2:])
            except ValueError:
                myappend('_' + item)
        else:
            myappend('_' + item)
    return "".join(res) 

def construct_change_message(self, request, form, formsets):
        """
        Construct a change message from a changed object.
        """
        change_message = []
        if form.changed_data:
            change_message.append(_('Changed %s.') % get_text_list(form.changed_data, _('and')))

        if formsets:
            for formset in formsets:
                for added_object in formset.new_objects:
                    change_message.append(_('Added %(name)s "%(object)s".')
                                          % {'name': force_text(added_object._meta.verbose_name),
                                             'object': force_text(added_object)})
                for changed_object, changed_fields in formset.changed_objects:
                    change_message.append(_('Changed %(list)s for %(name)s "%(object)s".')
                                          % {'list': get_text_list(changed_fields, _('and')),
                                             'name': force_text(changed_object._meta.verbose_name),
                                             'object': force_text(changed_object)})
                for deleted_object in formset.deleted_objects:
                    change_message.append(_('Deleted %(name)s "%(object)s".')
                                          % {'name': force_text(deleted_object._meta.verbose_name),
                                             'object': force_text(deleted_object)})
        change_message = ' '.join(change_message)
        return change_message or _('No fields changed.') 

def message_user(self, request, message, level=messages.INFO, extra_tags='',
                     fail_silently=False):
        """
        Send a message to the user. The default implementation
        posts a message using the django.contrib.messages backend.

        Exposes almost the same API as messages.add_message(), but accepts the
        positional arguments in a different order to maintain backwards
        compatibility. For convenience, it accepts the `level` argument as
        a string rather than the usual level number.
        """

        if not isinstance(level, int):
            # attempt to get the level if passed a string
            try:
                level = getattr(messages.constants, level.upper())
            except AttributeError:
                levels = messages.constants.DEFAULT_TAGS.values()
                levels_repr = ', '.join('`%s`' % l for l in levels)
                raise ValueError('Bad message level string: `%s`. '
                        'Possible values are: %s' % (level, levels_repr))

        messages.add_message(request, level, message, extra_tags=extra_tags,
                fail_silently=fail_silently) 

def as_sql(self):
        """
        Create the SQL for this query. Return the SQL string and list of
        parameters.
        """
        sql, params = [], []
        for annotation in self.query.annotation_select.values():
            ann_sql, ann_params = self.compile(annotation, select_format=FORCE)
            sql.append(ann_sql)
            params.extend(ann_params)
        self.col_count = len(self.query.annotation_select)
        sql = ', '.join(sql)
        params = tuple(params)

        sql = 'SELECT %s FROM (%s) subquery' % (sql, self.query.subquery)
        params = params + self.query.sub_params
        return sql, params 

def message_user(self, request, message, level=messages.INFO, extra_tags='',
                     fail_silently=False):
        """
        Send a message to the user. The default implementation
        posts a message using the django.contrib.messages backend.

        Exposes almost the same API as messages.add_message(), but accepts the
        positional arguments in a different order to maintain backwards
        compatibility. For convenience, it accepts the `level` argument as
        a string rather than the usual level number.
        """
        if not isinstance(level, int):
            # attempt to get the level if passed a string
            try:
                level = getattr(messages.constants, level.upper())
            except AttributeError:
                levels = messages.constants.DEFAULT_TAGS.values()
                levels_repr = ', '.join('`%s`' % l for l in levels)
                raise ValueError(
                    'Bad message level string: `%s`. Possible values are: %s'
                    % (level, levels_repr)
                )

        messages.add_message(request, level, message, extra_tags=extra_tags, fail_silently=fail_silently) 

def as_sql(self):
        """
        Create the SQL for this query. Return the SQL string and list of
        parameters.
        """
        sql, params = [], []
        for annotation in self.query.annotation_select.values():
            ann_sql, ann_params = self.compile(annotation, select_format=FORCE)
            sql.append(ann_sql)
            params.extend(ann_params)
        self.col_count = len(self.query.annotation_select)
        sql = ', '.join(sql)
        params = tuple(params)

        sql = 'SELECT %s FROM (%s) subquery' % (sql, self.query.subquery)
        params = params + self.query.sub_params
        return sql, params 

def display_for_value(value, empty_value_display, boolean=False):
    from django.contrib.admin.templatetags.admin_list import _boolean_icon

    if boolean:
        return _boolean_icon(value)
    elif value is None:
        return empty_value_display
    elif isinstance(value, datetime.datetime):
        return formats.localize(timezone.template_localtime(value))
    elif isinstance(value, (datetime.date, datetime.time)):
        return formats.localize(value)
    elif isinstance(value, (int, decimal.Decimal, float)):
        return formats.number_format(value)
    elif isinstance(value, (list, tuple)):
        return ', '.join(str(v) for v in value)
    else:
        return str(value) 

def demote_joins(self, aliases):
        """
        Change join type from LOUTER to INNER for all joins in aliases.

        Similarly to promote_joins(), this method must ensure no join chains
        containing first an outer, then an inner join are generated. If we
        are demoting b->c join in chain a LOUTER b LOUTER c then we must
        demote a->b automatically, or otherwise the demotion of b->c doesn't
        actually change anything in the query results. .
        """
        aliases = list(aliases)
        while aliases:
            alias = aliases.pop(0)
            if self.alias_map[alias].join_type == LOUTER:
                self.alias_map[alias] = self.alias_map[alias].demote()
                parent_alias = self.alias_map[alias].parent_alias
                if self.alias_map[parent_alias].join_type == INNER:
                    aliases.append(parent_alias) 

def unquote(s):
    """Undo the effects of quote(). Based heavily on urllib.parse.unquote()."""
    mychr = chr
    myatoi = int
    list = s.split('_')
    res = [list[0]]
    myappend = res.append
    del list[0]
    for item in list:
        if item[1:2]:
            try:
                myappend(mychr(myatoi(item[:2], 16)) + item[2:])
            except ValueError:
                myappend('_' + item)
        else:
            myappend('_' + item)
    return "".join(res) 

def trim_joins(self, targets, joins, path):
        """
        The 'target' parameter is the final field being joined to, 'joins'
        is the full list of join aliases. The 'path' contain the PathInfos
        used to create the joins.

        Return the final target field and table alias and the new active
        joins.

        Always trim any direct join if the target column is already in the
        previous table. Can't trim reverse joins as it's unknown if there's
        anything on the other side of the join.
        """
        joins = joins[:]
        for pos, info in enumerate(reversed(path)):
            if len(joins) == 1 or not info.direct:
                break
            if info.filtered_relation:
                break
            join_targets = {t.column for t in info.join_field.foreign_related_fields}
            cur_targets = {t.column for t in targets}
            if not cur_targets.issubset(join_targets):
                break
            targets_dict = {r[1].column: r[0] for r in info.join_field.related_fields if r[1].column in cur_targets}
            targets = tuple(targets_dict[t.column] for t in targets)
            self.unref_alias(joins.pop())
        return targets, joins[-1], joins 

def get_initial_alias(self):
        """
        Return the first alias for this query, after increasing its reference
        count.
        """
        if self.alias_map:
            alias = self.base_table
            self.ref_alias(alias)
        else:
            alias = self.join(BaseTable(self.get_meta().db_table, None))
        return alias 

def explain(self, using, format=None, **options):
        q = self.clone()
        q.explain_query = True
        q.explain_format = format
        q.explain_options = options
        compiler = q.get_compiler(using=using)
        return '\n'.join(compiler.explain_query()) 

def join(self, join, reuse=None, reuse_with_filtered_relation=False):
        """
        Return an alias for the 'join', either reusing an existing alias for
        that join or creating a new one. 'join' is either a
        sql.datastructures.BaseTable or Join.

        The 'reuse' parameter can be either None which means all joins are
        reusable, or it can be a set containing the aliases that can be reused.

        The 'reuse_with_filtered_relation' parameter is used when computing
        FilteredRelation instances.

        A join is always created as LOUTER if the lhs alias is LOUTER to make
        sure chains like t1 LOUTER t2 INNER t3 aren't generated. All new
        joins are created as LOUTER if the join is nullable.
        """
        if reuse_with_filtered_relation and reuse:
            reuse_aliases = [
                a for a, j in self.alias_map.items()
                if a in reuse and j.equals(join, with_filtered_relation=False)
            ]
        else:
            reuse_aliases = [
                a for a, j in self.alias_map.items()
                if (reuse is None or a in reuse) and j == join
            ]
        if reuse_aliases:
            self.ref_alias(reuse_aliases[0])
            return reuse_aliases[0]

        # No reuse is possible, so we need a new alias.
        alias, _ = self.table_alias(join.table_name, create=True, filtered_relation=join.filtered_relation)
        if join.join_type:
            if self.alias_map[join.parent_alias].join_type == LOUTER or join.nullable:
                join_type = LOUTER
            else:
                join_type = INNER
            join.join_type = join_type
        join.table_alias = alias
        self.alias_map[alias] = join
        return alias 

def get_current_prefetch_to(self, level):
        return LOOKUP_SEP.join(self.prefetch_to.split(LOOKUP_SEP)[:level + 1]) 

def quote(s):
    """
    Ensure that primary key values do not confuse the admin URLs by escaping
    any '/', '_' and ':' and similarly problematic characters.
    Similar to urllib.parse.quote(), except that the quoting is slightly
    different so that it doesn't get automatically unquoted by the Web browser.
    """
    if not isinstance(s, str):
        return s
    res = list(s)
    for i in range(len(res)):
        c = res[i]
        if c in """:/_#?;@&=+$,"[]<>%\n\\""":
            res[i] = '_%02X' % ord(c)
    return ''.join(res) 

def reverse_field_path(model, path):
    """ Create a reversed field path.

    E.g. Given (Order, "user__groups"),
    return (Group, "user__order").

    Final field must be a related model, not a data field.
    """
    reversed_path = []
    parent = model
    pieces = path.split(LOOKUP_SEP)
    for piece in pieces:
        field = parent._meta.get_field(piece)
        # skip trailing data field if extant:
        if len(reversed_path) == len(pieces) - 1:  # final iteration
            try:
                get_model_from_relation(field)
            except NotRelationField:
                break

        # Field should point to another model
        if field.is_relation and not (field.auto_created and not field.concrete):
            related_name = field.related_query_name()
            parent = field.remote_field.model
        else:
            related_name = field.field.name
            parent = field.related_model
        reversed_path.insert(0, related_name)
    return (parent, LOOKUP_SEP.join(reversed_path)) 

def reverse_field_path(model, path):
    """ Create a reversed field path.

    E.g. Given (Order, "user__groups"),
    return (Group, "user__order").

    Final field must be a related model, not a data field.
    """
    reversed_path = []
    parent = model
    pieces = path.split(LOOKUP_SEP)
    for piece in pieces:
        field = parent._meta.get_field(piece)
        # skip trailing data field if extant:
        if len(reversed_path) == len(pieces) - 1:  # final iteration
            try:
                get_model_from_relation(field)
            except NotRelationField:
                break

        # Field should point to another model
        if field.is_relation and not (field.auto_created and not field.concrete):
            related_name = field.related_query_name()
            parent = field.remote_field.model
        else:
            related_name = field.field.name
            parent = field.related_model
        reversed_path.insert(0, related_name)
    return (parent, LOOKUP_SEP.join(reversed_path)) 

def _extract_model_params(self, defaults, **kwargs):
        """
        Prepare `lookup` (kwargs that are valid model attributes), `params`
        (for creating a model instance) based on given kwargs; for use by
        get_or_create() and update_or_create().
        """
        defaults = defaults or {}
        lookup = kwargs.copy()
        for f in self.model._meta.fields:
            if f.attname in lookup:
                lookup[f.name] = lookup.pop(f.attname)
        params = {k: v for k, v in kwargs.items() if LOOKUP_SEP not in k}
        params.update(defaults)
        property_names = self.model._meta._property_names
        invalid_params = []
        for param in params:
            try:
                self.model._meta.get_field(param)
            except exceptions.FieldDoesNotExist:
                # It's okay to use a model's property if it has a setter.
                if not (param in property_names and getattr(self.model, param).fset):
                    invalid_params.append(param)
        if invalid_params:
            raise exceptions.FieldError(
                "Invalid field name(s) for model %s: '%s'." % (
                    self.model._meta.object_name,
                    "', '".join(sorted(invalid_params)),
                ))
        return lookup, params 

def quote(s):
    """
    Ensure that primary key values do not confuse the admin URLs by escaping
    any '/', '_' and ':' and similarly problematic characters.
    Similar to urllib.parse.quote(), except that the quoting is slightly
    different so that it doesn't get automatically unquoted by the Web browser.
    """
    if not isinstance(s, str):
        return s
    res = list(s)
    for i in range(len(res)):
        c = res[i]
        if c in """:/_#?;@&=+$,"[]<>%\n\\""":
            res[i] = '_%02X' % ord(c)
    return ''.join(res) 

def get_current_prefetch_to(self, level):
        return LOOKUP_SEP.join(self.prefetch_to.split(LOOKUP_SEP)[:level + 1]) 

def _validate_values_are_expressions(values, method_name):
        invalid_args = sorted(str(arg) for arg in values if not hasattr(arg, 'resolve_expression'))
        if invalid_args:
            raise TypeError(
                'QuerySet.%s() received non-expression(s): %s.' % (
                    method_name,
                    ', '.join(invalid_args),
                )
            ) 

def deferred_class_factory(model, attrs):
    """
    Returns a class object that is a copy of "model" with the specified "attrs"
    being replaced with DeferredAttribute objects. The "pk_value" ties the
    deferred attributes to a particular instance of the model.
    """
    if not attrs:
        return model
    # Never create deferred models based on deferred model
    if model._deferred:
        # Deferred models are proxies for the non-deferred model. We never
        # create chains of defers => proxy_for_model is the non-deferred
        # model.
        model = model._meta.proxy_for_model
    # The app registry wants a unique name for each model, otherwise the new
    # class won't be created (we get an exception). Therefore, we generate
    # the name using the passed in attrs. It's OK to reuse an existing class
    # object if the attrs are identical.
    name = "%s_Deferred_%s" % (model.__name__, '_'.join(sorted(list(attrs))))
    name = utils.truncate_name(name, 80, 32)

    try:
        return apps.get_model(model._meta.app_label, name)

    except LookupError:

        class Meta:
            proxy = True
            app_label = model._meta.app_label

        overrides = {attr: DeferredAttribute(attr, model) for attr in attrs}
        overrides["Meta"] = Meta
        overrides["__module__"] = model.__module__
        overrides["_deferred"] = True
        return type(str(name), (model,), overrides)


# The above function is also used to unpickle model instances with deferred
# fields. 

def add_fields(self, field_names, allow_m2m=True):
        """
        Add the given (model) fields to the select set. Add the field names in
        the order specified.
        """
        alias = self.get_initial_alias()
        opts = self.get_meta()

        try:
            cols = []
            for name in field_names:
                # Join promotion note - we must not remove any rows here, so
                # if there is no existing joins, use outer join.
                join_info = self.setup_joins(name.split(LOOKUP_SEP), opts, alias, allow_many=allow_m2m)
                targets, final_alias, joins = self.trim_joins(
                    join_info.targets,
                    join_info.joins,
                    join_info.path,
                )
                for target in targets:
                    cols.append(target.get_col(final_alias))
            if cols:
                self.set_select(cols)
        except MultiJoin:
            raise FieldError("Invalid field name: '%s'" % name)
        except FieldError:
            if LOOKUP_SEP in name:
                # For lookups spanning over relationships, show the error
                # from the model on which the lookup failed.
                raise
            else:
                names = sorted(
                    list(get_field_names_from_opts(opts)) + list(self.extra) +
                    list(self.annotation_select) + list(self._filtered_relations)
                )
                raise FieldError("Cannot resolve keyword %r into field. "
                                 "Choices are: %s" % (name, ", ".join(names))) 

def get_from_clause(self):
        """
        Return a list of strings that are joined together to go after the
        "FROM" part of the query, as well as a list any extra parameters that
        need to be included. Subclasses, can override this to create a
        from-clause via a "select".

        This should only be called after any SQL construction methods that
        might change the tables that are needed. This means the select columns,
        ordering, and distinct must be done first.
        """
        result = []
        params = []
        for alias in tuple(self.query.alias_map):
            if not self.query.alias_refcount[alias]:
                continue
            try:
                from_clause = self.query.alias_map[alias]
            except KeyError:
                # Extra tables can end up in self.tables, but not in the
                # alias_map if they aren't in a join. That's OK. We skip them.
                continue
            clause_sql, clause_params = self.compile(from_clause)
            result.append(clause_sql)
            params.extend(clause_params)
        for t in self.query.extra_tables:
            alias, _ = self.query.table_alias(t)
            # Only add the alias if it's not already present (the table_alias()
            # call increments the refcount, so an alias refcount of one means
            # this is the only reference).
            if alias not in self.query.alias_map or self.query.alias_refcount[alias] == 1:
                result.append(', %s' % self.quote_name_unless_alias(alias))
        return result, params