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Type error on upsert. #885

Merged
merged 9 commits into from
Apr 11, 2019
Merged

Type error on upsert. #885

merged 9 commits into from
Apr 11, 2019

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parsonsmatt
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@parsonsmatt parsonsmatt commented Apr 11, 2019 •
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This PR introduces a few type classes that are required on upsert and related functions that have expectations on how many unique keys a record has.

Instances for these classes are generated automatically, and "failing" instances get informative "TypeError"s when you misuse them.

Fixes #868
Fixes #796

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parsonsmatt commented Apr 11, 2019 •
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Weird, I am getting test suite failures locally for MongoDB:

  src/Init.hs:106:32: 
  1) persistent.putMany handles conflicts by replacing old keys with new records
       expected: [Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea9c3d4613542ae00082a}, entityVal = Upsert {upsertEmail = "putMany4", upsertAttr = "new", upsertExtra = "", upsertAge = 2}},Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea9c3d4613542ae00082b}, entityVal = Upsert {upsertEmail = "putMany5", upsertAttr = "new", upsertExtra = "", upsertAge = 2}},Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea7b6d46135390b00082d}, entityVal = Upsert {upsertEmail = "putMany6", upsertAttr = "new", upsertExtra = "", upsertAge = 2}},Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea7b6d46135390b00082c}, entityVal = Upsert {upsertEmail = "putMany7", upsertAttr = "new", upsertExtra = "", upsertAge = 2}}]
        but got: [Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea7b6d46135390b00082a}, entityVal = Upsert {upsertEmail = "putMany4", upsertAttr = "new", upsertExtra = "", upsertAge = 2}},Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea7b6d46135390b00082b}, entityVal = Upsert {upsertEmail = "putMany5", upsertAttr = "new", upsertExtra = "", upsertAge = 2}},Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea7b6d46135390b00082d}, entityVal = Upsert {upsertEmail = "putMany6", upsertAttr = "new", upsertExtra = "", upsertAge = 2}},Entity {entityKey = UpsertKey MongoKey {unMongoKey = 5caea7b6d46135390b00082c}, entityVal = Upsert {upsertEmail = "putMany7", upsertAttr = "new", upsertExtra = "", upsertAge = 2}}]

  To rerun use: --match "/persistent/putMany/handles conflicts by replacing old keys with new records/"

The IDs are different. I did not get these earlier when I was refactoring the test suite, and they don't appear to show up in CI?

parsonsmatt
parsonsmatt commented Apr 11, 2019
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persistent-template/Database/Persist/TH.hs Outdated
$ "Generating Persistent entities now requires the 'UndecidableInstances' "
<> "language extension. Please enable it in your file by copy/pasting "
<> "this line into the top of your file: \n\n"
<> "{-# LANGUAGE UndecidableInstances #-}"
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This gives a pretty pleasant error message. The alternative is a bit nasty.

persistent-template/Database/Persist/TH.hs Outdated

singleUniqueKey :: Q [Dec]
singleUniqueKey = do
expr <- [e|\p -> head (persistUniqueKeysP p)|]
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this is safe because we have already guaranteed that there are multiple unique keys

persistent-test/src/PersistentTest.hs
@@ -386,50 +386,6 @@ specsWith runDb = describe "persistent" $ do
pBlue30 <- updateGet key25 [PersonAge +=. 2]
pBlue30 @== Person "Updated" 30 Nothing

describe "putMany" $ do
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These specs are failing for MongoDB locally for me. The keys are changing, so it isn't updating, but replacing. Strange! I moved them into upsert specs which is pending for now.

persistent-template/Database/Persist/TH.hs

singleUniqueKey :: Q [Dec]
singleUniqueKey = do
expr <- [e|\p -> head (persistUniqueKeys p)|]
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this is "safe" because the generating code has already guaranteed that we have exactly one unique key.

persistent-template/Database/Persist/TH.hs

atLeastOneKey :: Q [Dec]
atLeastOneKey = do
expr <- [e|\p -> NEL.fromList (persistUniqueKeys p)|]
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likewise, this is safe because we have a guarantee from the generating code that it has at least one key.

persistent-mongoDB/test/EmbedTestMongo.hs
@@ -1,5 +1,6 @@
{-# OPTIONS_GHC -fno-warn-unused-binds -fno-warn-orphans -O0 #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE UndecidableInstances #-}
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This change requires UndecidableInstances. I give a nice error message for upgrading.

persistent-test/src/UpsertTest.hs
@@ -165,3 +165,48 @@ specsWith runDb handleNull handleKey = describe "UpsertTests" $ do
Just 2
Don'tUpdateNull ->
Nothing

describe "putMany" $ do
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Moved from the PersistentTest module so that mongoDB could skip them for now.

persistent/Database/Persist/Class/PersistUnique.hs
-- | Update based on a uniqueness constraint or insert:
--
-- * insert the new record if it does not exist;
-- * If the record exists (matched via it's uniqueness constraint), then update the existing record with the parameters which is passed on as list to the function.
--
-- Throws an exception if there is more than 1 uniqueness constraint.
--
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👋

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Do we need to bump the major versions of the component libraries? eg persistent-mysql exports Database.Persist.Sql which has these changes. But it's interface does not change at all, and you need to depend on persistent anyway to use this stuff.

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Ah, dang. We can't do TypeError unless we drop support for GHC 7.10.3.

@parsonsmatt parsonsmatt merged commit 04d03e9 into master Apr 11, 2019
@parsonsmatt parsonsmatt deleted the matt/type-error-on-upsert branch April 11, 2019 21:25
@dbaynard dbaynard mentioned this pull request Jul 15, 2019
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