openpyxl.packaging.relationship 源代码

from __future__ import absolute_import
# Copyright (c) 2010-2019 openpyxl

import posixpath

from openpyxl.descriptors import (
    String,
    Set,
    NoneSet,
    Alias,
    Sequence,
)
from openpyxl.descriptors.serialisable import Serialisable

from openpyxl.xml.constants import REL_NS, PKG_REL_NS
from openpyxl.xml.functions import (
    Element,
    fromstring,
    tostring
)


[文档]class Relationship(Serialisable): """Represents many kinds of relationships.""" tagname = "Relationship" Type = String() Target = String() target = Alias("Target") TargetMode = String(allow_none=True) Id = String(allow_none=True) id = Alias("Id") def __init__(self, Id=None, Type=None, type=None, Target=None, TargetMode=None ): """ `type` can be used as a shorthand with the default relationships namespace otherwise the `Type` must be a fully qualified URL """ if type is not None: Type = "{0}/{1}".format(REL_NS, type) self.Type = Type self.Target = Target self.TargetMode = TargetMode self.Id = Id
[文档]class RelationshipList(Serialisable): tagname = "Relationships" Relationship = Sequence(expected_type=Relationship) def __init__(self, Relationship=()): self.Relationship = Relationship
[文档] def append(self, value): values = self.Relationship[:] values.append(value) if not value.Id: value.Id = "rId{0}".format((len(values))) self.Relationship = values
def __len__(self): return len(self.Relationship) def __bool__(self): return bool(self.Relationship)
[文档] def find(self, content_type): """ Find relationships by content-type NB. these content-types namespaced objects and different to the MIME-types in the package manifest :-( """ for r in self.Relationship: if r.Type == content_type: yield r
def __getitem__(self, key): for r in self.Relationship: if r.Id == key: return r raise KeyError("Unknown relationship: {0}".format(key))
[文档] def to_tree(self): tree = Element("Relationships", xmlns=PKG_REL_NS) for idx, rel in enumerate(self.Relationship, 1): if not rel.Id: rel.Id = "rId{0}".format(idx) tree.append(rel.to_tree()) return tree
[文档]def get_rels_path(path): """ Convert relative path to absolutes that can be loaded from a zip archive. The path to be passed in is that of containing object (workbook, worksheet, etc.) """ folder, obj = posixpath.split(path) filename = posixpath.join(folder, '_rels', '{0}.rels'.format(obj)) return filename
from warnings import warn
[文档]def get_dependents(archive, filename): """ Normalise dependency file paths to absolute ones Relative paths are relative to parent object """ src = archive.read(filename) node = fromstring(src) try: rels = RelationshipList.from_tree(node) except TypeError: msg = "{0} contains invalid dependency definitions".format(filename) warn(msg) rels = RelationshipList() folder = posixpath.dirname(filename) parent = posixpath.split(folder)[0] for r in rels.Relationship: if r.TargetMode == "External": continue elif r.target.startswith("/"): r.target = r.target[1:] else: pth = posixpath.join(parent, r.target) r.target = posixpath.normpath(pth) return rels
[文档]def get_rel(archive, deps, id=None, cls=None): """ Get related object based on id or rel_type """ if not any([id, cls]): raise ValueError("Either the id or the content type are required") if id is not None: rel = deps[id] else: try: rel = next(deps.find(cls.rel_type)) except StopIteration: # no known dependency return path = rel.target src = archive.read(path) tree = fromstring(src) obj = cls.from_tree(tree) rels_path = get_rels_path(path) try: obj.deps = get_dependents(archive, rels_path) except KeyError: obj.deps = [] return obj