support ad-hoc models

src/infi/clickhouse_orm/database.py

@@ -1,4 +1,6 @@
 import requests
+from models import ModelBase
+from utils import escape, parse_tsv
 
 
 class DatabaseException(Exception):
@@ -47,10 +49,14 @@ class Database(object):
         return int(r.text) if r.text else 0
 
     def select(self, query, model_class=None, settings=None):
-        query += ' FORMAT TabSeparated'
+        query += ' FORMAT TabSeparatedWithNamesAndTypes'
         r = self._send(query, settings)
-        for line in r.iter_lines():
+        lines = r.iter_lines()
-            yield model_class.from_tsv(line)
+        field_names = parse_tsv(next(lines))
+        field_types = parse_tsv(next(lines))
+        model_class = model_class or ModelBase.create_ad_hoc_model(zip(field_names, field_types))
+        for line in lines:
+            yield model_class.from_tsv(line, field_names)
 
     def _send(self, data, settings=None):
         params = self._build_params(settings)

src/infi/clickhouse_orm/models.py

@@ -1,6 +1,6 @@
-from fields import *
 from utils import escape, parse_tsv
 from engines import *
+from fields import Field
 
 
 class ModelBase(type):
@@ -16,6 +16,18 @@ class ModelBase(type):
         setattr(new_cls, '_fields', fields)
         return new_cls
 
+    @classmethod
+    def create_ad_hoc_model(cls, fields):
+        # fields is a list of tuples (name, db_type)
+        import fields as orm_fields
+        attrs = {}
+        for name, db_type in fields:
+            field_class = db_type + 'Field'
+            if not hasattr(orm_fields, field_class):
+                raise NotImplementedError('No field class for %s' % db_type)
+            attrs[name] = getattr(orm_fields, field_class)()
+        return cls.__new__(cls, 'AdHocModel', (Model,), attrs)
+
 
 class Model(object):
     '''
@@ -77,16 +89,18 @@ class Model(object):
         return 'DROP TABLE IF EXISTS %s.%s' % (db_name, cls.table_name())
 
     @classmethod
-    def from_tsv(cls, line):
+    def from_tsv(cls, line, field_names=None):
         '''
         Create a model instance from a tab-separated line. The line may or may not include a newline.
+        The field_names list must match the fields defined in the model, but does not have to include all of them.
+        If omitted, it is assumed to be the names of all fields in the model, in order of definition.
         '''
+        field_names = field_names or [name for name, field in cls._fields]
         values = iter(parse_tsv(line))
         kwargs = {}
-        for name, field in cls._fields:
+        for name in field_names:
             kwargs[name] = values.next()
         return cls(**kwargs)
-        # TODO verify that the number of values matches the number of fields
 
     def to_tsv(self):
         '''

tests/test_database.py

@@ -37,7 +37,7 @@ class DatabaseTestCase(unittest.TestCase):
         self.assertEquals(self.database.count(Person), 100)
         self.assertEquals(self.database.count(Person, "first_name = 'Courtney'"), 2)
         self.assertEquals(self.database.count(Person, "birthday > '2000-01-01'"), 22)
-        self.assertEquals(self.database.count(Person, "birthday < '1900-01-01'"), 0)
+        self.assertEquals(self.database.count(Person, "birthday < '1970-03-01'"), 0)
 
     def test_select(self):
         self._insert_and_check(self._sample_data(), len(data))
@@ -45,7 +45,30 @@ class DatabaseTestCase(unittest.TestCase):
         results = list(self.database.select(query, Person))
         self.assertEquals(len(results), 2)
         self.assertEquals(results[0].last_name, 'Durham')
+        self.assertEquals(results[0].height, 1.72)
         self.assertEquals(results[1].last_name, 'Scott')
+        self.assertEquals(results[1].height, 1.70)
+
+    def test_select_partial_fields(self):
+        self._insert_and_check(self._sample_data(), len(data))
+        query = "SELECT first_name, last_name FROM test_db.person WHERE first_name = 'Whitney' ORDER BY last_name"
+        results = list(self.database.select(query, Person))
+        self.assertEquals(len(results), 2)
+        self.assertEquals(results[0].last_name, 'Durham')
+        self.assertEquals(results[0].height, 0) # default value
+        self.assertEquals(results[1].last_name, 'Scott')
+        self.assertEquals(results[1].height, 0) # default value
+
+    def test_select_ad_hoc_model(self):
+        self._insert_and_check(self._sample_data(), len(data))
+        query = "SELECT * FROM test_db.person WHERE first_name = 'Whitney' ORDER BY last_name"
+        results = list(self.database.select(query))
+        self.assertEquals(len(results), 2)
+        self.assertEquals(results[0].__class__.__name__, 'AdHocModel')
+        self.assertEquals(results[0].last_name, 'Durham')
+        self.assertEquals(results[0].height, 1.72)
+        self.assertEquals(results[1].last_name, 'Scott')
+        self.assertEquals(results[1].height, 1.70)
 
     def _sample_data(self):
         for entry in data: