A patch to add multi level prefetch to persistencejs, a javascript ORM.

multilevel_prefetch.patch

From b6b903a3f6f9c1d5113bf98baab12bbfa009dadf Mon Sep 17 00:00:00 2001
From: Sebastian Herrlinger <sebastian@formzoo.com>
Date: Fri, 16 Sep 2011 13:36:58 -0700
Subject: [PATCH 1/3] Hack: Multi Level Prefetch

---
 lib/persistence.store.sql.js |   34 +++++++++++++++++++++++++++++-----
 1 files changed, 29 insertions(+), 5 deletions(-)
 mode change 100644 => 100755 lib/persistence.store.sql.js

diff --git a/lib/persistence.store.sql.js b/lib/persistence.store.sql.js
old mode 100644
new mode 100755
index 70916cc..5d68b99
--- a/lib/persistence.store.sql.js
+++ b/lib/persistence.store.sql.js
@@ -644,15 +644,28 @@ function config(persistence, dialect) {
     joinSql += this._additionalJoinSqls.join(' ');
 
     for ( var i = 0; i < this._prefetchFields.length; i++) {
-      var prefetchField = this._prefetchFields[i];
-      var thisMeta = meta.hasOne[prefetchField].type.meta;
+      console.log(this._prefetchFields[i]);
+      var prefetchFieldParts = this._prefetchFields[i].split('.');
+      var prefetchField = prefetchFieldParts[0];
+      var eName = entityName;
+      //console.log(prefetchField, eName);
+      if(prefetchFieldParts.length > 1){
+        prefetchField = prefetchFieldParts[1];
+        eName = prefetchFieldParts[0];
+      }
+      var theMeta = persistence.getMeta(eName);
+      var thisMeta = theMeta.hasOne[prefetchField].type.meta;
       if (thisMeta.isMixin)
         throw new Error("cannot prefetch a mixin");
       var tableAlias = thisMeta.name + '_' + prefetchField + "_tbl";
+      var PrefetchFrom = mainAlias;
+      if(prefetchFieldParts.length > 1){
+        PrefetchFrom = eName + '_' + eName + "_tbl";;
+      }
       selectFields = selectFields.concat(selectAll(thisMeta, tableAlias,
           prefetchField + "_"));
       joinSql += "LEFT JOIN `" + thisMeta.name + "` AS `" + tableAlias
-      + "` ON `" + tableAlias + "`.`id` = `" + mainAlias + '`.`' + prefetchField + "` ";
+      + "` ON `" + tableAlias + "`.`id` = `" + PrefetchFrom + '`.`' + prefetchField + "` ";
 
     }
 
@@ -690,8 +703,19 @@ function config(persistence, dialect) {
               var r = rows[i];
               var e = rowToEntity(session, entityName, r, mainPrefix);
               for ( var j = 0; j < that._prefetchFields.length; j++) {
-                var prefetchField = that._prefetchFields[j];
-                var thisMeta = meta.hasOne[prefetchField].type.meta;
+                
+                console.log(that._prefetchFields[j]);
+                var prefetchFieldParts = that._prefetchFields[j].split('.');
+                var prefetchField = prefetchFieldParts[0];
+                var eName = entityName;
+                if(prefetchFieldParts.length > 1){
+                  prefetchField = prefetchFieldParts[1];
+                  eName = prefetchFieldParts[0];
+                }
+                var theMeta = persistence.getMeta(eName);
+                var thisMeta = theMeta.hasOne[prefetchField].type.meta;
+                
+                console.log(thisMeta.name, prefetchField, eName);
                 e._data_obj[prefetchField] = rowToEntity(session, thisMeta.name, r, prefetchField + '_');
                 session.add(e._data_obj[prefetchField]);
               }
-- 
1.7.0.4


From f33ca4f57e22b751ae5e49f230ece5fdd4adb5ee Mon Sep 17 00:00:00 2001
From: Sebastian Herrlinger <sebastian@formzoo.com>
Date: Fri, 16 Sep 2011 13:40:58 -0700
Subject: [PATCH 2/3] removed hack output

---
 lib/persistence.store.sql.js |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/lib/persistence.store.sql.js b/lib/persistence.store.sql.js
index 5d68b99..6f0da49 100755
--- a/lib/persistence.store.sql.js
+++ b/lib/persistence.store.sql.js
@@ -644,11 +644,9 @@ function config(persistence, dialect) {
     joinSql += this._additionalJoinSqls.join(' ');
 
     for ( var i = 0; i < this._prefetchFields.length; i++) {
-      console.log(this._prefetchFields[i]);
       var prefetchFieldParts = this._prefetchFields[i].split('.');
       var prefetchField = prefetchFieldParts[0];
       var eName = entityName;
-      //console.log(prefetchField, eName);
       if(prefetchFieldParts.length > 1){
         prefetchField = prefetchFieldParts[1];
         eName = prefetchFieldParts[0];
@@ -704,7 +702,6 @@ function config(persistence, dialect) {
               var e = rowToEntity(session, entityName, r, mainPrefix);
               for ( var j = 0; j < that._prefetchFields.length; j++) {
                 
-                console.log(that._prefetchFields[j]);
                 var prefetchFieldParts = that._prefetchFields[j].split('.');
                 var prefetchField = prefetchFieldParts[0];
                 var eName = entityName;
@@ -715,7 +712,6 @@ function config(persistence, dialect) {
                 var theMeta = persistence.getMeta(eName);
                 var thisMeta = theMeta.hasOne[prefetchField].type.meta;
                 
-                console.log(thisMeta.name, prefetchField, eName);
                 e._data_obj[prefetchField] = rowToEntity(session, thisMeta.name, r, prefetchField + '_');
                 session.add(e._data_obj[prefetchField]);
               }
-- 
1.7.0.4


From be9e2a5dac5018cac12f3da12c138e3435b8f68f Mon Sep 17 00:00:00 2001
From: Sebastian Herrlinger <sebastian@formzoo.com>
Date: Wed, 21 Sep 2011 16:42:10 -0700
Subject: [PATCH 3/3] Remove debug output

---
 lib/persistence.js |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
 mode change 100644 => 100755 lib/persistence.js

diff --git a/lib/persistence.js b/lib/persistence.js
old mode 100644
new mode 100755
index 217fe14..53daae8
--- a/lib/persistence.js
+++ b/lib/persistence.js
@@ -442,7 +442,6 @@ persistence.get = function(arg1, arg2) {
                         }
                       }
                       if(oldValueObj) {
-                        console.log("OldValue", oldValueObj);
                         var inverse = oldValueObj[meta.hasOne[ref].inverseProperty];
                         if(inverse.list && inverse._filter) {
                           inverse.triggerEvent('change', that, ref, val);
-- 
1.7.0.4