From 4dc42faab3734ccad7dd8951d6f190e9868dc37f Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sun, 17 Jul 2005 01:17:33 +0000
Subject: [PATCH] basic eager loading

---
 lib/sqlalchemy/engine.py | 26 +++++++++++++++++
 lib/sqlalchemy/mapper.py | 62 ++++++++++------------------------------
 lib/sqlalchemy/sql.py    |  4 +++
 test/mapper.py           |  1 -
 4 files changed, 45 insertions(+), 48 deletions(-)

diff --git a/lib/sqlalchemy/engine.py b/lib/sqlalchemy/engine.py
index 0814caf573..6ea026159e 100644
--- a/lib/sqlalchemy/engine.py
+++ b/lib/sqlalchemy/engine.py
@@ -132,3 +132,29 @@ class SQLEngine(schema.SchemaEngine):
 
     def log(self, msg):
         print msg
+
+
+class ResultProxy:
+    def __init__(self, cursor):
+        self.cursor = cursor
+        metadata = cursor.description
+        self.props = {}
+        i = 0
+        for item in metadata:
+            self.props[item[0]] = i
+            self.props[i] = i
+            i+=1
+
+    def fetchone(self):
+        row = self.cursor.fetchone()
+        if row is not None:
+            return RowProxy(self, row)
+        else:
+            return None
+
+class RowProxy:
+    def __init__(self, parent, row):
+        self.parent = parent
+        self.row = row
+    def __getitem__(self, key):
+        return self.row[self.parent.props[key]]
diff --git a/lib/sqlalchemy/mapper.py b/lib/sqlalchemy/mapper.py
index 2a178b56b6..ed0ebe3b04 100644
--- a/lib/sqlalchemy/mapper.py
+++ b/lib/sqlalchemy/mapper.py
@@ -36,14 +36,16 @@ addressmapper = Mapper(Address, addresses, properties = {
 
 import sqlalchemy.sql as sql
 import sqlalchemy.schema as schema
+import sqlalchemy.engine as engine
 
 class Mapper(object):
-    def __init__(self, class_, selectable, properties = None, identitymap = None):
+    def __init__(self, class_, selectable, table = None, properties = None, identitymap = None):
         self.class_ = class_
-
         self.selectable = selectable
-        self.table = self._find_table(selectable)
-        
+        if table is None:
+            self.table = self._find_table(selectable)
+        else:
+            self.table = table
         self.props = {}
         
         for column in self.selectable.columns:
@@ -60,15 +62,15 @@ class Mapper(object):
             
     def instances(self, cursor):
         result = []
-        cursor = ResultProxy(cursor)
+        cursor = engine.ResultProxy(cursor)
         localmap = IdentityMap()
         while True:
             row = cursor.fetchone()
             if row is None:
                 break
                 
-            identitykey = localmap.get_key(row, self.class_, self.table, self.selectable)
-            if not localmap.map.has_key(identitykey):
+            identitykey = self._identity_key(row)
+            if not localmap.has_key(identitykey):
                 instance = self._create(row, identitykey, localmap)
                 result.append(instance)
             else:
@@ -104,6 +106,8 @@ class Mapper(object):
 
     class TableFinder(sql.ClauseVisitor):
         def visit_table(self, table):
+            if hasattr(self, 'table'):
+                raise "Mapper can only create object instances against a single-table identity - specify the 'table' argument to the Mapper constructor"
             self.table = table
             
     def _find_table(self, selectable):
@@ -131,8 +135,8 @@ class Mapper(object):
                 return None
         for key, prop in self.props.iteritems():
             prop.execute(instance, key, row, identitykey, localmap, False)
-        self.identitymap.map[identitykey] = instance
-        localmap.map[identitykey] = instance
+        self.identitymap[identitykey] = instance
+        localmap[identitykey] = instance
         return instance
 
 
@@ -176,46 +180,10 @@ class EagerLoader(MapperProperty):
             subinstance = self.mapper._create(row, identitykey, localmap)
             list.append(subinstance)
 
-class ResultProxy:
-    def __init__(self, cursor):
-        self.cursor = cursor
-        metadata = cursor.description
-        self.props = {}
-        i = 0
-        for item in metadata:
-            self.props[item[0]] = i
-            self.props[i] = i
-            i+=1
-
-    def fetchone(self):
-        row = self.cursor.fetchone()
-        print "row: " + repr(row)
-        if row is not None:
-            return RowProxy(self, row)
-        else:
-            return None
-        
-class RowProxy:
-    def __init__(self, parent, row):
-        self.parent = parent
-        self.row = row
-    def __getitem__(self, key):
-        return self.row[self.parent.props[key]]
-        
-class IdentityMap(object):
-    def __init__(self):
-        self.map = {}
-        self.keystereotypes = {}
-    
-    def has_key(self, key):
-        return self.map.has_key(key)
         
+class IdentityMap(dict):
     def get_key(self, row, class_, table, selectable):
         return (class_, table, tuple([row[column.label] for column in selectable.primary_keys]))
         
-    def get(self, key):
-        return self.map[key]
-            
-    
-    
+
 _global_identitymap = IdentityMap()
diff --git a/lib/sqlalchemy/sql.py b/lib/sqlalchemy/sql.py
index 7438408d69..0bd9fa3826 100644
--- a/lib/sqlalchemy/sql.py
+++ b/lib/sqlalchemy/sql.py
@@ -126,6 +126,10 @@ class ClauseElement(object):
         c = self.compile(e, bindparams = params)
         return e.execute(str(c), c.get_params(**params))
 
+    def result(self, **params):
+        e = self._engine()
+        c = self.compile(e, bindparams = params)
+        return e.result(str(c), c.get_params(**params))
         
 class ColumnClause(ClauseElement):
     """represents a column clause element in a SQL statement."""
diff --git a/test/mapper.py b/test/mapper.py
index a2fc249c75..3d0ee0b8ac 100644
--- a/test/mapper.py
+++ b/test/mapper.py
@@ -99,7 +99,6 @@ class MapperTest(PersistTest):
         ), identitymap = mapper.IdentityMap())
         l = m.select()
         print repr(l)
-        print repr(m.identitymap.map)
 
         
     def tearDown(self):
-- 
2.47.2