diff options
Diffstat (limited to 'examples/elementtree/adjacency_list.py')
| -rw-r--r-- | examples/elementtree/adjacency_list.py | 150 |
1 files changed, 102 insertions, 48 deletions
diff --git a/examples/elementtree/adjacency_list.py b/examples/elementtree/adjacency_list.py index 5e27ba9ca..1f7161212 100644 --- a/examples/elementtree/adjacency_list.py +++ b/examples/elementtree/adjacency_list.py @@ -15,42 +15,63 @@ styles of persistence are identical, as is the structure of the main Document cl """ ################################# PART I - Imports/Coniguration #################################### -from sqlalchemy import (MetaData, Table, Column, Integer, String, ForeignKey, - Unicode, and_, create_engine) +from sqlalchemy import ( + MetaData, + Table, + Column, + Integer, + String, + ForeignKey, + Unicode, + and_, + create_engine, +) from sqlalchemy.orm import mapper, relationship, Session, lazyload import sys, os, io, re from xml.etree import ElementTree -e = create_engine('sqlite://') +e = create_engine("sqlite://") meta = MetaData() ################################# PART II - Table Metadata ######################################### # stores a top level record of an XML document. -documents = Table('documents', meta, - Column('document_id', Integer, primary_key=True), - Column('filename', String(30), unique=True), - Column('element_id', Integer, ForeignKey('elements.element_id')) +documents = Table( + "documents", + meta, + Column("document_id", Integer, primary_key=True), + Column("filename", String(30), unique=True), + Column("element_id", Integer, ForeignKey("elements.element_id")), ) # stores XML nodes in an adjacency list model. This corresponds to # Element and SubElement objects. -elements = Table('elements', meta, - Column('element_id', Integer, primary_key=True), - Column('parent_id', Integer, ForeignKey('elements.element_id')), - Column('tag', Unicode(30), nullable=False), - Column('text', Unicode), - Column('tail', Unicode) - ) +elements = Table( + "elements", + meta, + Column("element_id", Integer, primary_key=True), + Column("parent_id", Integer, ForeignKey("elements.element_id")), + Column("tag", Unicode(30), nullable=False), + Column("text", Unicode), + Column("tail", Unicode), +) # stores attributes. This corresponds to the dictionary of attributes # stored by an Element or SubElement. -attributes = Table('attributes', meta, - Column('element_id', Integer, ForeignKey('elements.element_id'), primary_key=True), - Column('name', Unicode(100), nullable=False, primary_key=True), - Column('value', Unicode(255))) +attributes = Table( + "attributes", + meta, + Column( + "element_id", + Integer, + ForeignKey("elements.element_id"), + primary_key=True, + ), + Column("name", Unicode(100), nullable=False, primary_key=True), + Column("value", Unicode(255)), +) meta.create_all(e) @@ -68,6 +89,7 @@ class Document(object): self.element.write(buf) return buf.getvalue() + #################################### PART IV - Persistence Mapping ################################# # Node class. a non-public class which will represent @@ -78,6 +100,7 @@ class Document(object): class _Node(object): pass + # Attribute class. also internal, this will represent the key/value attributes stored for # a particular Node. class _Attribute(object): @@ -85,16 +108,25 @@ class _Attribute(object): self.name = name self.value = value + # setup mappers. Document will eagerly load a list of _Node objects. -mapper(Document, documents, properties={ - '_root':relationship(_Node, lazy='joined', cascade="all") -}) +mapper( + Document, + documents, + properties={"_root": relationship(_Node, lazy="joined", cascade="all")}, +) -mapper(_Node, elements, properties={ - 'children':relationship(_Node, cascade="all"), - # eagerly load attributes - 'attributes':relationship(_Attribute, lazy='joined', cascade="all, delete-orphan"), -}) +mapper( + _Node, + elements, + properties={ + "children": relationship(_Node, cascade="all"), + # eagerly load attributes + "attributes": relationship( + _Attribute, lazy="joined", cascade="all, delete-orphan" + ), + }, +) mapper(_Attribute, attributes) @@ -106,7 +138,7 @@ class ElementTreeMarshal(object): if document is None: return self - if hasattr(document, '_element'): + if hasattr(document, "_element"): return document._element def traverse(node, parent=None): @@ -132,7 +164,9 @@ class ElementTreeMarshal(object): n.text = str(node.text) n.tail = str(node.tail) n.children = [traverse(n2) for n2 in node] - n.attributes = [_Attribute(str(k), str(v)) for k, v in node.attrib.items()] + n.attributes = [ + _Attribute(str(k), str(v)) for k, v in node.attrib.items() + ] return n document._root = traverse(element.getroot()) @@ -142,6 +176,7 @@ class ElementTreeMarshal(object): del document._element document._root = [] + # override Document's "element" attribute with the marshaller. Document.element = ElementTreeMarshal() @@ -153,7 +188,7 @@ line = "\n--------------------------------------------------------" session = Session(e) # get ElementTree documents -for file in ('test.xml', 'test2.xml', 'test3.xml'): +for file in ("test.xml", "test2.xml", "test3.xml"): filename = os.path.join(os.path.dirname(__file__), file) doc = ElementTree.parse(filename) session.add(Document(file, doc)) @@ -170,10 +205,16 @@ print(document) ############################################ PART VI - Searching for Paths ######################### # manually search for a document which contains "/somefile/header/field1:hi" -d = session.query(Document).join('_root', aliased=True).filter(_Node.tag=='somefile').\ - join('children', aliased=True, from_joinpoint=True).filter(_Node.tag=='header').\ - join('children', aliased=True, from_joinpoint=True).filter( - and_(_Node.tag=='field1', _Node.text=='hi')).one() +d = ( + session.query(Document) + .join("_root", aliased=True) + .filter(_Node.tag == "somefile") + .join("children", aliased=True, from_joinpoint=True) + .filter(_Node.tag == "header") + .join("children", aliased=True, from_joinpoint=True) + .filter(and_(_Node.tag == "field1", _Node.text == "hi")) + .one() +) print(d) # generalize the above approach into an extremely impoverished xpath function: @@ -181,26 +222,39 @@ def find_document(path, compareto): j = documents prev_elements = None query = session.query(Document) - attribute = '_root' - for i, match in enumerate(re.finditer(r'/([\w_]+)(?:\[@([\w_]+)(?:=(.*))?\])?', path)): + attribute = "_root" + for i, match in enumerate( + re.finditer(r"/([\w_]+)(?:\[@([\w_]+)(?:=(.*))?\])?", path) + ): (token, attrname, attrvalue) = match.group(1, 2, 3) - query = query.join(attribute, aliased=True, from_joinpoint=True).filter(_Node.tag==token) - attribute = 'children' + query = query.join( + attribute, aliased=True, from_joinpoint=True + ).filter(_Node.tag == token) + attribute = "children" if attrname: if attrvalue: - query = query.join('attributes', aliased=True, from_joinpoint=True).filter( - and_(_Attribute.name==attrname, _Attribute.value==attrvalue)) + query = query.join( + "attributes", aliased=True, from_joinpoint=True + ).filter( + and_( + _Attribute.name == attrname, + _Attribute.value == attrvalue, + ) + ) else: - query = query.join('attributes', aliased=True, from_joinpoint=True).filter( - _Attribute.name==attrname) - return query.options(lazyload('_root')).filter(_Node.text==compareto).all() + query = query.join( + "attributes", aliased=True, from_joinpoint=True + ).filter(_Attribute.name == attrname) + return ( + query.options(lazyload("_root")).filter(_Node.text == compareto).all() + ) + for path, compareto in ( - ('/somefile/header/field1', 'hi'), - ('/somefile/field1', 'hi'), - ('/somefile/header/field2', 'there'), - ('/somefile/header/field2[@attr=foo]', 'there') - ): + ("/somefile/header/field1", "hi"), + ("/somefile/field1", "hi"), + ("/somefile/header/field2", "there"), + ("/somefile/header/field2[@attr=foo]", "there"), +): print("\nDocuments containing '%s=%s':" % (path, compareto), line) print([d.filename for d in find_document(path, compareto)]) - |