Initial attempt at enabling reading the columns from the datasource

setup.py

@@ -5,7 +5,7 @@
 
 setup(
     name='tableaudocumentapi',
-    version='0.1.0-dev',
+    version='0.1.0.dev0',
     author='Tableau Software',
     author_email='[email protected]',
     url='https://github.com/tableau/document-api-python',

tableaudocumentapi/__init__.py

@@ -1,5 +1,7 @@
+from .field import Field
 from .connection import Connection
 from .datasource import Datasource, ConnectionParser
 from .workbook import Workbook
+
 __version__ = '0.0.1'
 __VERSION__ = __version__

tableaudocumentapi/datasource.py

@@ -3,15 +3,29 @@
 # Datasource - A class for writing datasources to Tableau files
 #
 ###############################################################################
-import os
+import collections
+import xml.etree.ElementTree as ET
+import xml.sax.saxutils as sax
 import zipfile
 
-import xml.etree.ElementTree as ET
 from tableaudocumentapi import Connection, xfile
+from tableaudocumentapi import Field
+from tableaudocumentapi.multilookup_dict import MultiLookupDict
 
 
-class ConnectionParser(object):
+def _mapping_from_xml(root_xml, column_xml):
+    retval = Field.from_xml(column_xml)
+    local_name = retval.id
+    if "'" in local_name:
+        local_name = sax.escape(local_name, {"'": "'"})
+    xpath = ".//metadata-record[@class='column'][local-name='{}']".format(local_name)
+    metadata_record = root_xml.find(xpath)
+    if metadata_record is not None:
+        retval.apply_metadata(metadata_record)
+    return retval.id, retval
 
+
+class ConnectionParser(object):
     def __init__(self, datasource_xml, version):
         self._dsxml = datasource_xml
         self._dsversion = version
@@ -55,6 +69,7 @@ def __init__(self, dsxml, filename=None):
         self._connection_parser = ConnectionParser(
             self._datasourceXML, version=self._version)
         self._connections = self._connection_parser.get_connections()
+        self._fields = None
 
     @classmethod
     def from_file(cls, filename):
@@ -115,3 +130,17 @@ def version(self):
     @property
     def connections(self):
         return self._connections
+
+    ###########
+    # fields
+    ###########
+    @property
+    def fields(self):
+        if not self._fields:
+            self._fields = self._get_all_fields()
+        return self._fields
+
+    def _get_all_fields(self):
+        column_objects = (_mapping_from_xml(self._datasourceTree, xml)
+                          for xml in self._datasourceTree.findall('.//column'))
+        return MultiLookupDict({k: v for k, v in column_objects})

tableaudocumentapi/field.py

@@ -0,0 +1,89 @@
+import functools
+
+_ATTRIBUTES = [
+    'id',           # Name of the field as specified in the file, usually surrounded by [ ]
+    'caption',      # Name of the field as displayed in Tableau unless an aliases is defined
+    'datatype',     # Type of the field within Tableau (string, integer, etc)
+    'role',         # Dimension or Measure
+    'type',         # three possible values: quantitative, ordinal, or nominal
+    'alias',        # Name of the field as displayed in Tableau if the default name isn't wanted
+    'calculation',  # If this field is a calculated field, this will be the formula
+]
+
+_METADATA_ATTRIBUTES = [
+    'aggregation',  # The type of aggregation on the field (e.g Sum, Avg)
+]
+
+
+def _find_metadata_record(record, attrib):
+    element = record.find('.//{}'.format(attrib))
+    if element is None:
+        return None
+    return element.text
+
+
+class Field(object):
+    """ Represents a field in a datasource """
+
+    def __init__(self, xmldata):
+        for attrib in _ATTRIBUTES:
+            self._apply_attribute(xmldata, attrib, lambda x: xmldata.attrib.get(x, None))
+
+        # All metadata attributes begin at None
+        for attrib in _METADATA_ATTRIBUTES:
+            setattr(self, '_{}'.format(attrib), None)
+
+    def apply_metadata(self, metadata_record):
+        for attrib in _METADATA_ATTRIBUTES:
+            self._apply_attribute(metadata_record, attrib, functools.partial(_find_metadata_record, metadata_record))
+
+    @classmethod
+    def from_xml(cls, xmldata):
+        return cls(xmldata)
+
+    def __getattr__(self, item):
+        private_name = '_{}'.format(item)
+        if item in _ATTRIBUTES or item in _METADATA_ATTRIBUTES:
+            return getattr(self, private_name)
+        raise AttributeError(item)
+
+    def _apply_attribute(self, xmldata, attrib, default_func):
+        if hasattr(self, '_read_{}'.format(attrib)):
+            value = getattr(self, '_read_{}'.format(attrib))(xmldata)
+        else:
+            value = default_func(attrib)
+
+        setattr(self, '_{}'.format(attrib), value)
+
+    @property
+    def name(self):
+        """ Provides a nice name for the field which is derived from the alias, caption, or the id.
+
+        The name resolves as either the alias if it's defined, or the caption if alias is not defined,
+        and finally the id which is the underlying name if neither of the fields exist. """
+        alias = getattr(self, 'alias', None)
+        if alias:
+            return alias
+
+        caption = getattr(self, 'caption', None)
+        if caption:
+            return caption
+
+        return self.id
+
+    ######################################
+    # Special Case handling methods for reading the values from the XML
+    ######################################
+    @staticmethod
+    def _read_id(xmldata):
+        # ID is actually the name of the field, but to provide a nice name, we call this ID
+        return xmldata.attrib.get('name', None)
+
+    @staticmethod
+    def _read_calculation(xmldata):
+        # The formula for a calculation is stored in a child element, so we need to pull it out separately.
+        calc = xmldata.find('.//calculation')
+        if calc is None:
+            return None
+
+        return calc.attrib.get('formula', None)

tableaudocumentapi/multilookup_dict.py

@@ -0,0 +1,49 @@
+def _resolve_value(key, value):
+    try:
+        retval = value.get(key, None)
+        if retval is None:
+            retval = value.getattr(key, None)
+    except AttributeError:
+        retval = None
+    return retval
+
+
+def _build_index(key, d):
+    return {_resolve_value(key, v): k
+            for k, v in d.items()
+            if _resolve_value(key, v) is not None}
+
+
+# TODO: Improve this to be more generic
+class MultiLookupDict(dict):
+    def __init__(self, args=None):
+        if args is None:
+            args = {}
+        super(MultiLookupDict, self).__init__(args)
+        self._indexes = {
+            'alias': {},
+            'caption': {}
+        }
+        self._populate_indexes()
+
+    def _populate_indexes(self):
+        self._indexes['alias'] = _build_index('alias', self)
+        self._indexes['caption'] = _build_index('caption', self)
+
+    def __setitem__(self, key, value):
+        alias = _resolve_value('alias', value)
+        caption = _resolve_value('caption', value)
+        if alias is not None:
+            self._indexes['alias'][alias] = key
+        if caption is not None:
+            self._indexes['caption'][caption] = key
+
+        dict.__setitem__(self, key, value)
+
+    def __getitem__(self, key):
+        if key in self._indexes['alias']:
+            key = self._indexes['alias'][key]
+        elif key in self._indexes['caption']:
+            key = self._indexes['caption'][key]
+
+        return dict.__getitem__(self, key)

test/__init__.py

@@ -0,0 +1,2 @@
+from . import bvt
+from . import test_datasource

test/assets/datasource_test.tds

@@ -0,0 +1,86 @@
+<?xml version='1.0' encoding='utf-8' ?>
+<datasource formatted-name='postgres.1of3kl00aoax5d1a1ejma1397430' inline='true' source-platform='mac' version='9.3' xmlns:user='http://www.tableausoftware.com/xml/user'>
+  <connection authentication='username-password' class='postgres' dbname='TestV1' odbc-native-protocol='yes' port='5432' server='postgres91.test.tsi.lan' username='test'>
+    <relation name='xy' table='[public].[xy]' type='table' />
+    <metadata-records>
+      <metadata-record class='column'>
+        <remote-name>a</remote-name>
+        <remote-type>130</remote-type>
+        <local-name>[a]</local-name>
+        <parent-name>[xy]</parent-name>
+        <remote-alias>a</remote-alias>
+        <ordinal>1</ordinal>
+        <local-type>string</local-type>
+        <aggregation>Count</aggregation>
+        <width>255</width>
+        <contains-null>true</contains-null>
+        <attributes>
+          <attribute datatype='string' name='DebugRemoteType'>&quot;SQL_WVARCHAR&quot;</attribute>
+          <attribute datatype='string' name='DebugWireType'>&quot;SQL_C_WCHAR&quot;</attribute>
+          <attribute datatype='string' name='TypeIsVarchar'>&quot;true&quot;</attribute>
+        </attributes>
+      </metadata-record>
+      <metadata-record class='column'>
+        <remote-name>Today's Date</remote-name>
+        <remote-type>130</remote-type>
+        <local-name>[Today&apos;s Date]</local-name>
+        <parent-name>[xy]</parent-name>
+        <remote-alias>a</remote-alias>
+        <ordinal>1</ordinal>
+        <local-type>string</local-type>
+        <aggregation>Count</aggregation>
+        <width>255</width>
+        <contains-null>true</contains-null>
+        <attributes>
+          <attribute datatype='string' name='DebugRemoteType'>&quot;SQL_WVARCHAR&quot;</attribute>
+          <attribute datatype='string' name='DebugWireType'>&quot;SQL_C_WCHAR&quot;</attribute>
+          <attribute datatype='string' name='TypeIsVarchar'>&quot;true&quot;</attribute>
+        </attributes>
+      </metadata-record>
+      <metadata-record class='column'>
+        <remote-name>x</remote-name>
+        <remote-type>3</remote-type>
+        <local-name>[x]</local-name>
+        <parent-name>[xy]</parent-name>
+        <remote-alias>x</remote-alias>
+        <ordinal>2</ordinal>
+        <local-type>integer</local-type>
+        <aggregation>Sum</aggregation>
+        <precision>10</precision>
+        <contains-null>true</contains-null>
+        <attributes>
+          <attribute datatype='string' name='DebugRemoteType'>&quot;SQL_INTEGER&quot;</attribute>
+          <attribute datatype='string' name='DebugWireType'>&quot;SQL_C_SLONG&quot;</attribute>
+        </attributes>
+      </metadata-record>
+      <metadata-record class='column'>
+        <remote-name>y</remote-name>
+        <remote-type>3</remote-type>
+        <local-name>[y]</local-name>
+        <parent-name>[xy]</parent-name>
+        <remote-alias>y</remote-alias>
+        <ordinal>3</ordinal>
+        <local-type>integer</local-type>
+        <aggregation>Sum</aggregation>
+        <precision>10</precision>
+        <contains-null>true</contains-null>
+        <attributes>
+          <attribute datatype='string' name='DebugRemoteType'>&quot;SQL_INTEGER&quot;</attribute>
+          <attribute datatype='string' name='DebugWireType'>&quot;SQL_C_SLONG&quot;</attribute>
+        </attributes>
+      </metadata-record>
+    </metadata-records>
+  </connection>
+  <aliases enabled='yes' />
+  <column datatype='integer' name='[Number of Records]' role='measure' type='quantitative' user:auto-column='numrec'>
+    <calculation class='tableau' formula='1' />
+  </column>
+  <column caption='A' datatype='string' name='[a]' role='dimension' type='nominal' />
+  <column caption='Today&apos;s Date' datatype='string' name='[Today&apos;s Date]' role='dimension' type='nominal' />
+  <column caption='X' datatype='integer' name='[x]' role='measure' type='quantitative' />
+  <column caption='Y' datatype='integer' name='[y]' role='measure' type='quantitative' />
+  <layout dim-ordering='alphabetic' dim-percentage='0.5' measure-ordering='alphabetic' measure-percentage='0.5' show-structure='true' />
+  <semantic-values>
+    <semantic-value key='[Country].[Name]' value='&quot;United States&quot;' />
+  </semantic-values>
+</datasource>

test/test_datasource.py

@@ -0,0 +1,29 @@
+import unittest
+import os.path
+import functools
+
+from tableaudocumentapi import Datasource
+
+TEST_TDS_FILE = os.path.join(
+    os.path.dirname(__file__),
+    'assets',
+    'datasource_test.tds'
+)
+
+
+class DataSourceFields(unittest.TestCase):
+    def setUp(self):
+        self.ds = Datasource.from_file(TEST_TDS_FILE)
+
+    def test_datasource_returns_correct_fields(self):
+        self.assertIsNotNone(self.ds.fields)
+        self.assertIsNotNone(self.ds.fields.get('[Number of Records]', None))
+
+    def test_datasource_returns_calculation_from_fields(self):
+        self.assertEqual('1', self.ds.fields['[Number of Records]'].calculation)
+
+    def test_datasource_uses_metadata_record(self):
+        self.assertEqual('Sum', self.ds.fields['[x]'].aggregation)
+
+    def test_datasource_column_name_contains_apostrophy(self):
+        self.assertIsNotNone(self.ds.fields.get("[Today's Date]", None))

test/test_multidict.py

@@ -0,0 +1,47 @@
+import unittest
+import os.path
+import functools
+
+from tableaudocumentapi.multilookup_dict import MultiLookupDict
+
+
+class MLDTests(unittest.TestCase):
+    def setUp(self):
+        self.mld = MultiLookupDict({
+            '[foo]': {
+                'alias': 'bar',
+                'caption': 'baz',
+                'value': 1
+            },
+            '[bar]': {
+                'caption': 'foo',
+                'value': 2
+            },
+            '[baz]': {
+                'value': 3
+            }
+        })
+
+    def test_multilookupdict_name_only(self):
+        actual = self.mld['[baz]']
+        self.assertEqual(3, actual['value'])
+
+    def test_multilookupdict_alias_overrides_everything(self):
+        actual = self.mld['bar']
+        self.assertEqual(1, actual['value'])
+
+    def test_mutlilookupdict_caption_overrides_id(self):
+        actual = self.mld['foo']
+        self.assertEqual(2, actual['value'])
+
+    def test_mutlilookupdict_can_still_find_id_even_with_alias(self):
+        actual = self.mld['[foo]']
+        self.assertEqual(1, actual['value'])
+
+    def test_mutlilookupdict_can_still_find_caption_even_with_alias(self):
+        actual = self.mld['baz']
+        self.assertEqual(1, actual['value'])
+
+    def test_mutlilookupdict_can_still_find_id_even_with_caption(self):
+        actual = self.mld['[bar]']
+        self.assertEqual(2, actual['value'])