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# XML-database conversion
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import re
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import traceback
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from xml.dom import Node
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import exc
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import sql
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import strings
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import util
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import xml_dom
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def name_of(node): return re.sub(r'^.*\.', r'', node.tagName)
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ptr_suffix = '_id'
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def is_ptr(node_name): return node_name.lower().endswith(ptr_suffix)
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def ptr_type_guess(node_name):
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    assert is_ptr(node_name)
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    return node_name[:-len(ptr_suffix)]
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def ptr_target(node):
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    assert is_ptr(name_of(node))
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    return xml_dom.first_elem(node)
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def find_by_name(node, name):
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    for parent in xml_dom.NodeParentIter(node):
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        if name_of(parent) == name: return parent
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        else:
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            for child in xml_dom.NodeElemIter(parent):
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                child_name = name_of(child)
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                if is_ptr(child_name):
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                    target = ptr_target(child)
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                    if target.tagName == name: return target
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                elif child_name == name: return child
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    return None
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def get(db, node, limit=None, start=None):
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    def pkey(table): return sql.pkey(db, table)
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    node = node.firstChild
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    table = name_of(node)
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    pkey_ = pkey(table)
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    fields = []
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    conds = {}
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    for child in xml_dom.NodeElemIter(node):
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        child_name = name_of(child)
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        if xml_dom.is_empty(child): fields.append(child_name)
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        elif xml_dom.is_text(child): conds[child_name] = xml_dom.value(child)
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        else: raise Exception('Joins not supported yet')
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    id_ = xml_dom.get_id(node)
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    if id_ != None: conds[pkey(table)] = id_ # replace any existing pkey value
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    if fields == []: fields.append(pkey_)
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    return sql.select(db, table, fields, conds, limit, start)
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def put(db, node, row_ct_ref=None, on_error=exc.raise_, pool=None,
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    store_ids=False, parent_id=None):
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    '''store_ids enables searching the tree for missing fields'''
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    def pkey(table): return sql.pkey(db, table, True)
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    def put_(node, parent_id=None):
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        args = (db, node, row_ct_ref, on_error, pool, store_ids, parent_id)
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        if parent_id != None and pool != None: pool.apply_async(put, args)
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        else: return put(*args)
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    def on_error_(e):
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        exc.add_msg(e, 'node:\n'+str(node))
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        on_error(e)
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    table = name_of(node)
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    try: pkey_ = pkey(table)
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    except sql.DatabaseErrors, e: on_error_(e); return None
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    row = {}
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    children = []
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    # Divide children into fields and children with fkeys to parent
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    for child in xml_dom.NodeElemIter(node):
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        child_name = name_of(child)
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        if xml_dom.is_empty(child): row[child_name] = None
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        elif xml_dom.is_text(child):
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            row[child_name] = strings.to_unicode(xml_dom.value(child))
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        elif is_ptr(child_name): row[child_name] = put_(ptr_target(child))
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        else: children.append(child)
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    try: del row[pkey_]
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    except KeyError: pass
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    # Add fkey to parent
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    if parent_id != None:
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        parent_ptr = node.getAttribute('fkey')
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        if parent_ptr == '': parent_ptr = pkey(name_of(node.parentNode))
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        row[parent_ptr] = parent_id
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    # Insert node
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    try:
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        for try_num in xrange(2):
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            try:
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                id_ = sql.put(db, table, row, pkey_, row_ct_ref)
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                if store_ids: xml_dom.set_id(node, id_)
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                break
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            except sql.NullValueException, e:
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                col = e.cols[0]
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                if try_num > 0: raise # exception still raised after retry
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                if store_ids and is_ptr(col):
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                    # Search for required column in ancestors and their children
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                    target = find_by_name(node, ptr_type_guess(col))
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                    if target == None: raise
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                    row[col] = xml_dom.get_id(target)
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                else: raise
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    except sql.DatabaseErrors, e: on_error_(e); return None
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    # Insert children with fkeys to parent
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    for child in children: put_(child, id_)
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    return id_
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def put_table(db, node, table, commit=False, row_ct_ref=None,
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    table_is_esc=False):
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    '''
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    @param node The XML tree that transforms the input to the output. Similar to
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        put()'s node param, but with the input column name prefixed by "$" in
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        place of the column value.
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    @param commit Whether to commit after each query
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    '''
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    import sys; sys.stderr.write(str(node))
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    if commit: db.db.commit()
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    raise NotImplementedError('By-column optimization not available yet')
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