Create New Connections per #68

tableaudocumentapi/connection.py

@@ -3,6 +3,7 @@
 # Connection - A class for writing connections to Tableau files
 #
 ###############################################################################
+import xml.etree.ElementTree as ET
 from tableaudocumentapi.dbclass import is_valid_dbclass
 
 
@@ -33,6 +34,17 @@ def __init__(self, connxml):
     def __repr__(self):
         return "'<Connection server='{}' dbname='{}' @ {}>'".format(self._server, self._dbname, hex(id(self)))
 
+    @classmethod
+    def from_attributes(cls, server, dbname, username, dbclass, authentication=''):
+        root = ET.Element('connection', authentication=authentication)
+        xml = cls(root)
+        xml.server = server
+        xml.dbname = dbname
+        xml.username = username
+        xml.dbclass = dbclass
+
+        return xml
+
     ###########
     # dbname
     ###########
@@ -120,4 +132,4 @@ def dbclass(self, value):
             raise AttributeError("'{}' is not a valid database type".format(value))
 
         self._class = value
-        self._connectionXML.set('dbclass', value)
+        self._connectionXML.set('class', value)

tableaudocumentapi/datasource.py

@@ -5,8 +5,10 @@
 ###############################################################################
 import collections
 import itertools
+import random
 import xml.etree.ElementTree as ET
 import xml.sax.saxutils as sax
+from uuid import uuid4
 
 from tableaudocumentapi import Connection, xfile
 from tableaudocumentapi import Field
@@ -38,6 +40,7 @@ def _is_used_by_worksheet(names, field):
 
 
 class FieldDictionary(MultiLookupDict):
+
     def used_by_sheet(self, name):
         # If we pass in a string, no need to get complicated, just check to see if name is in
         # the field's list of worksheets
@@ -63,7 +66,36 @@ def _column_object_from_metadata_xml(metadata_xml):
     return _ColumnObjectReturnTuple(field_object.id, field_object)
 
 
+def base36encode(number):
+    """Converts an integer into a base36 string."""
+
+    ALPHABET = "0123456789abcdefghijklmnopqrstuvwxyz"
+
+    base36 = ''
+    sign = ''
+
+    if number < 0:
+        sign = '-'
+        number = -number
+
+    if 0 <= number < len(ALPHABET):
+        return sign + ALPHABET[number]
+
+    while number != 0:
+        number, i = divmod(number, len(ALPHABET))
+        base36 = ALPHABET[i] + base36
+
+    return sign + base36
+
+
+def make_unique_name(dbclass):
+    rand_part = base36encode(uuid4().int)
+    name = dbclass + '.' + rand_part
+    return name
+
+
 class ConnectionParser(object):
+
     def __init__(self, datasource_xml, version):
         self._dsxml = datasource_xml
         self._dsversion = version
@@ -116,6 +148,20 @@ def from_file(cls, filename):
         dsxml = xml_open(filename, cls.__name__.lower()).getroot()
         return cls(dsxml, filename)
 
+    @classmethod
+    def from_connections(cls, caption, connections):
+        root = ET.Element('datasource', caption=caption, version='10.0', inline='true')
+        outer_connection = ET.SubElement(root, 'connection')
+        outer_connection.set('class', 'federated')
+        named_conns = ET.SubElement(outer_connection, 'named-connections')
+        for conn in connections:
+            nc = ET.SubElement(named_conns,
+                               'named-connection',
+                               name=make_unique_name(conn.dbclass),
+                               caption=conn.server)
+            nc.append(conn._connectionXML)
+        return cls(root)
+
     def save(self):
         """
         Call finalization code and save file.
@@ -143,6 +189,7 @@ def save_as(self, new_filename):
             Nothing.
 
         """
+
         xfile._save_file(self._filename, self._datasourceTree, new_filename)
 
     ###########

tableaudocumentapi/xfile.py

@@ -104,6 +104,10 @@ def save_into_archive(xml_tree, filename, new_filename=None):
 
 
 def _save_file(container_file, xml_tree, new_filename=None):
+
+    if container_file is None:
+        container_file = new_filename
+
     if zipfile.is_zipfile(container_file):
         save_into_archive(xml_tree, container_file, new_filename)
     else:

test/bvt.py

@@ -74,6 +74,25 @@ def test_bad_dbclass_rasies_attribute_error(self):
         with self.assertRaises(AttributeError):
             conn.dbclass = 'NotReal'
 
+    def test_can_create_connection_from_scratch(self):
+        conn = Connection.from_attributes(
+            server='a', dbname='b', username='c', dbclass='mysql', authentication='d')
+        self.assertEqual(conn.server, 'a')
+        self.assertEqual(conn.dbname, 'b')
+        self.assertEqual(conn.username, 'c')
+        self.assertEqual(conn.dbclass, 'mysql')
+        self.assertEqual(conn.authentication, 'd')
+
+    def test_can_create_datasource_from_connections(self):
+        conn1 = Connection.from_attributes(
+            server='a', dbname='b', username='c', dbclass='mysql', authentication='d')
+        conn2 = Connection.from_attributes(
+            server='1', dbname='2', username='3', dbclass='mysql', authentication='7')
+        ds = Datasource.from_connections('test', connections=[conn1, conn2])
+
+        self.assertEqual(ds.connections[0].server, 'a')
+        self.assertEqual(ds.connections[1].server, '1')
+
 
 class DatasourceModelTests(unittest.TestCase):