Migrating a table with a custom primary key fails in SQLite

[JaSpa]

Description

Let's say we have this model definition

A
  fieldA Int
  Primary fieldA

and change it to

A
  fieldA Int
  fieldB Int default=0
  Primary fieldA

The migration fails with table a_backup has no column named id, because the generated SQL still includes the non-existing id-column although we have a custom primary key:

CREATE TEMP TABLE "a_backup"("fieldA" INTEGER NOT NULL,"field_b" INTEGER NOT NULL DEFAULT 0, PRIMARY KEY ("fieldA"));
INSERT INTO "a_backup"("id","fieldA") SELECT "id","fieldA" FROM "a";

Identified problem

The problem lies in these two lines, as they prepend the id column regardless of its actual existence.

Patch

This following patch works for me, but I don't really understand the ReferenceDef type, but if I have got it correctly and there are no other cases to consider, I'll prepare a pull request + test case.

diff --git a/persistent-sqlite/Database/Persist/Sqlite.hs b/persistent-sqlite/Database/Persist/Sqlite.hs
index ab72ec7..d811578 100644
--- a/persistent-sqlite/Database/Persist/Sqlite.hs
+++ b/persistent-sqlite/Database/Persist/Sqlite.hs
@@ -375,12 +375,11 @@ getCopyTable allDefs getter def = do
     let oldCols = map DBName $ filter (/= "id") oldCols' -- need to update for table id attribute ?
     let newCols = filter (not . safeToRemove def) $ map cName cols
     let common = filter (`elem` oldCols) newCols
-    let id_ = fieldDB (entityId def)
     return [ (False, tmpSql)
-           , (False, copyToTemp $ id_ : common)
+           , (False, copyToTemp $ addIdCol common)
            , (common /= filter (not . safeToRemove def) oldCols, dropOld)
            , (False, newSql)
-           , (False, copyToFinal $ id_ : newCols)
+           , (False, copyToFinal $ addIdCol newCols)
            , (False, dropTmp)
            ]
   where
@@ -418,6 +417,10 @@ getCopyTable allDefs getter def = do
         , " FROM "
         , escape tableTmp
         ]
+    addIdCol = let id_ = entityId def
+                in case fieldReference id_ of
+                     CompositeRef _ -> id
+                     _ -> (fieldDB id_ :)
 
 mkCreateTable :: Bool -> EntityDef -> ([Column], [UniqueDef]) -> Text
 mkCreateTable isTemp entity (cols, uniqs) =

[gregwebs]

Looks good. Probably use the entityPrimary helper.