persistent-template
Type-safe, non-relational, multi-backend persistence.
http://www.yesodweb.com/book/persistent
LTS Haskell 22.43: | 2.12.0.0 |
Stackage Nightly 2024-12-04: | 2.12.0.0 |
Latest on Hackage: | 2.12.0.0 |
persistent-template-2.12.0.0@sha256:7c68de6624ff83e14b674745e1c895dcf7c8676f6f24be131c89e2e4c2fa4510,1008
Module documentation for 2.12.0.0
There are no documented modules for this package.
Begone!
This package was absorbed into persistent
with the 2.12.0.1 release.
persistent-template
Provides Template Haskell helpers for persistent. For more information, see the chapter in the Yesod book.
code organization
The TH.hs module contains code generators.
persistent-template uses EntityDef
s that it gets from the quasi-quoter.
The quasi-quoter is in persistent Quasi.hs
Similarly many of the types come from the persistent library
Development tips
To get a better idea of what code you’re generating, you can output the content of Template Haskell expressions to a file:
stack test persistent-template --ghc-options='-ddump-splices -ddump-to-file'
The output will be in the .stack-work
directory. The exact path will depend on your specific setup, but if you search for files ending in .dump-splices
you’ll find the output (find .stack-work -type f -name '*.dump-splices'
)
If you make changes to the generated code, it is highly recommended to compare the output with your changes to output from master
(even better if this diff is included in your PR!). Seemingly small changes can have dramatic changes on the generated code.
For example, embedding an EntityDef
in a function that was called for every field of that Entity
made the number of generated lines O(N^2) for that function—very bad!
Changes
Unreleased changes
2.12.0.0
- Decomposed
HaskellName
intoConstraintNameHS
,EntityNameHS
,FieldNameHS
. DecomposedDBName
intoConstraintNameDB
,EntityNameDB
,FieldNameDB
respectively. #1174 - #1214:
- This package was asborbed into
persistent
itself.
- This package was asborbed into
2.9.1.0
- #1145
- Fix a bug where the
SqlType
for a shared primary key was being incorrectly set toSqlString
instead of whatever the target primary key sql type was.
- Fix a bug where the
- #1151
- Automatically generate
SymbolToField
instances for datatypes, allowingOverloadedLabels
to be used with theEntityField
type.
- Automatically generate
2.9
-
Always use the “stock” strategy when deriving Show/Read for keys #1106
- This fixes a regression from 2.8.0, which started using the
newtype
strategy when derivingShow
/Read
for keys - In practice, this means that from 2.8.0–2.8.3.1, for the following schema:
Person name Text CustomPrimary anInt Int Primary anInt name Text
PersonKey 1
would show as"SqlBackendKey {unSqlBackendKey = 1}"
andCustomPrimaryKey 1
would show as"1"
This was generally poor for debugging and logging, since all tables keys would print the same. For Persistent < 2.8.0 and > 2.8.3.1, they instead will show as:
"PersonKey {unPersonKey = SqlBackendKey {unSqlBackendKey = 1}}"
and"CustomPrimaryKey {unCustomPrimaryKey = 1}"
This could be a breaking change if you have used
Show
on a key, wrote that string into some persistent storage like a database, and are trying toRead
it back again later. - This fixes a regression from 2.8.0, which started using the
2.8.3.1
- Allow aeson 1.5. #1085
2.8.3.0
- Add
Lift
instances for the cascade types. #1060 - Use
DeriveLift
to implement allLift
instances. Among other benefits, this provides implementations ofliftTyped
ontemplate-haskell-2.16
(GHC 8.10) or later. #1064
2.8.2.3
- Require extensions in a more friendly manner. #1030
- Specify a strategy for all deriving clauses, which avoids the
-Wmissing-deriving-strategy
warning introduced in GHC 8.8.2. #1030
2.8.2.2
- Fix the
mkPersist
function to not require importing the classes explicitly. #1027
2.8.2.1
- Fix the test-suite for persistent-template. #1023
2.8.2
- Add
fieldError
to the export list ofDatabase.Persist.TH
#1008
2.8.1
- Let the user pass instances that will be derived for record and for key types (https://github.com/yesodweb/persistent/pull/990
2.8.0.1
- Small optimization/code cleanup to generated Template Haskell code size, by slimming the implementation of to/fromPersistValue for Entities. #1014
2.8.0
- Reduces the amount of code generated by Template Haskell. The amount of code generated for a certain function was O(N^2) with respect to the number of fields on a given Entity. This change shows dramatic improvements in benchmarks for compiling Persistent models. #
- Drops support for GHC 8.0, so that
DerivingStrategies
can be used bypersistent-template
persistent-template
now requiresDerivingStrategies
,GeneralizedNewtypeDeriving
, andStandaloneDeriving
to be enabled in the file where Persistent entities are created- Fixes a long-standing issue where persistent-template would fail when
DeriveAnyClass
was enabled (See #578) - #1002
2.7.4
- Remove an overlapping instance for
Lift a
. #998
2.7.3
- Update module documentation for
Database.Persist.TH
to better describe the purpose of the module #968 - Support template-haskell-2.15 #959
2.7.2
- Expose the knot tying logic of
parseReferences
so that users can build migrations from independently define entities at runtime #932
2.7.1
2.7.0
- Depends on
persistent-2.10.0
which provides theOnlyOneUniqueKey
andAtLeastOneUniqueKey
classes. Automatically generates instances for these classes based on how many unique keys the entity definition gets. This changes requiresUndecidableInstances
to be enabled on each module that generates entity definitions. #885 - Removed deprecated
sqlOnlySettings
. Please usesqlSettings
instead. #894
2.6.0
- persistent#846: Improve error message when marshalling fails
- persistent#826: Change
Unique
deriveShow
2.5.4
- persistent#778: Add
persistManyFileWith
.
2.5.3.1
- Slight improvement to the error message when a Persistent field can’t be parsed from database results
2.5.3
- Exposed
parseReferences
to allow custom QuasiQuoters
2.5.2
- Fix incorrect
ToJSON
/FromJSON
instance generation for generic backends
2.5.1.6
Allow non-null self-references in a list
2.5.1.4
- Allow composite Primary keys for tables that contain nullable fields.
- Support foreign keys to non-integer ids
2.5.1.3
- fix GHC 7.8 bug when a field name is “type”
2.5.1.2
- fix a bad Eq instance /= definition for Key when mpsGenetric=True
2.5.0.1
- workaround TH bug in GHC 7.10
2.5
- read/write typeclass split
2.1.6
- aeson 0.11
- transformers 0.5
2.1.4
support http-api-data for url serialization
2.1.3.3
By default explicitly use Int64 for foreign key references. This avoids confusion on a 32 bit system.
2.1.3.1
Support foreign key references to composite primary keys
2.1.0.1
Support for monad-control 1.0