## Description
### I want to speak to the `Manager`
Oh boy. This PR is both fairly straightforward and overreaching, so let's break it down.
For most network access, we need a [`HTTP.Manager`](https://hackage.haskell.org/package/http-client-0.1.0.0/docs/Network-HTTP-Client-Manager.html). It is created only once, at the top level, when starting the engine, and is then threaded through the application to wherever we need to make a network call. As of main, the way we do this is not standardized: most of the GraphQL execution code passes it "manually" as a function argument throughout the code. We also have a custom monad constraint, `HasHttpManagerM`, that describes a monad's ability to provide a manager. And, finally, several parts of the code store the manager in some kind of argument structure, such as `RunT`'s `RunCtx`.
This PR's first goal is to harmonize all of this: we always create the manager at the root, and we already have it when we do our very first `runReaderT`. Wouldn't it make sense for the rest of the code to not manually pass it anywhere, to not store it anywhere, but to always rely on the current monad providing it? This is, in short, what this PR does: it implements a constraint on the base monads, so that they provide the manager, and removes most explicit passing from the code.
### First come, first served
One way this PR goes a tiny bit further than "just" doing the aforementioned harmonization is that it starts the process of implementing the "Services oriented architecture" roughly outlined in this [draft document](https://docs.google.com/document/d/1FAigqrST0juU1WcT4HIxJxe1iEBwTuBZodTaeUvsKqQ/edit?usp=sharing). Instead of using the existing `HasHTTPManagerM`, this PR revamps it into the `ProvidesNetwork` service.
The idea is, again, that we should make all "external" dependencies of the engine, all things that the core of the engine doesn't care about, a "service". This allows us to define clear APIs for features, to choose different implementations based on which version of the engine we're running, harmonizes our many scattered monadic constraints... Which is why this service is called "Network": we can refine it, moving forward, to be the constraint that defines how all network communication is to operate, instead of relying on disparate classes constraint or hardcoded decisions. A comment in the code clarifies this intent.
### Side-effects? In my Haskell?
This PR also unavoidably touches some other aspects of the codebase. One such example: it introduces `Hasura.App.AppContext`, named after `HasuraPro.Context.AppContext`: a name for the reader structure at the base level. It also transforms `Handler` from a type alias to a newtype, as `Handler` is where we actually enforce HTTP limits; but without `Handler` being a distinct type, any code path could simply do a `runExceptT $ runReader` and forget to enforce them.
(As a rule of thumb, i am starting to consider any straggling `runReaderT` or `runExceptT` as a code smell: we should not stack / unstack monads haphazardly, and every layer should be an opaque `newtype` with a corresponding run function.)
## Further work
In several places, i have left TODOs when i have encountered things that suggest that we should do further unrelated cleanups. I'll write down the follow-up steps, either in the aforementioned document or on slack. But, in short, at a glance, in approximate order, we could:
- delete `ExecutionCtx` as it is only a subset of `ServerCtx`, and remove one more `runReaderT` call
- delete `ServerConfigCtx` as it is only a subset of `ServerCtx`, and remove it from `RunCtx`
- remove `ServerCtx` from `HandlerCtx`, and make it part of `AppContext`, or even make it the `AppContext` altogether (since, at least for the OSS version, `AppContext` is there again only a subset)
- remove `CacheBuildParams` and `CacheBuild` altogether, as they're just a distinct stack that is a `ReaderT` on top of `IO` that contains, you guessed it, the same thing as `ServerCtx`
- move `RunT` out of `RQL.Types` and rename it, since after the previous cleanups **it only contains `UserInfo`**; it could be bundled with the authentication service, made a small implementation detail in `Hasura.Server.Auth`
- rename `PGMetadaStorageT` to something a bit more accurate, such as `App`, and enforce its IO base
This would significantly simply our complex stack. From there, or in parallel, we can start moving existing dependencies as Services. For the purpose of supporting read replicas entitlement, we could move `MonadResolveSource` to a `SourceResolver` service, as attempted in #7653, and transform `UserAuthenticationM` into a `Authentication` service.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7736
GitOrigin-RevId: 68cce710eb9e7d752bda1ba0c49541d24df8209f
### Description
Each Backend executes queries against the database in a slightly different stack: Postgres uses its own `TXeT`, MSSQL uses a variant of it, BigQuery is simply in `ExceptT QErr IO`... To accommodate those variations, we had originally introduced an `ExecutionMonad b` type family in `BackendExecute`, allowing each backend to describe its own stack. It was then up to that backend's `BackendTransport` instance to implement running said stack, and converting the result back into our main app monad.
However, this was not without complications: `TraceT` is one of them: as it usually needs to be on the top of the stack, converting from one stack to the other implies the use `interpTraceT`, which is quite monstrous. Furthermore, as part of the Entitlement Services work, we're trying to move to a "Services" architecture in which the entire engine runs in one base monad, that delegates features and dependencies to monad constraints; and as a result we'd like to minimize the number of different monad stacks we have to maintain and translate from and to in the codebase.
To improve things, this PR changes `ExecutionMonad b` from an _absolute_ stack to a _relative_ one: i.e.: what needs to be stacked on top of our base monad for the execution. In `Transport`, we then only need to pop the top of the stack, and voila. This greatly simplifies the implementation of the backends, as there's no longer any need to do any stack transformation: MySQL's implementation becomes a `runIdentityT`! This also removes most mentions of `TraceT` from the execution code since it's no longer required: we can rely on the base monad's existing `MonadTrace` constraint.
To continue encapsulating monadic actions in `DBStepInfo` and avoid threading a bunch of `forall` all over the place, this PR introduces a small local helper: `OnBaseMonad`. One only downside of all this is that this requires adding `MonadBaseControl IO m` constraint all over the place: previously, we would run directly on `IO` and lift, and would therefore not need to bring that constraint all the way.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7789
GitOrigin-RevId: e9b2e431c5c47fa9851abf87545c0415ff6d1a12
Basic MongoDB agent. This is intended as a starting point for playing with nested documents in a MongoDB back end. Currently supports basic queries with projections, where expressions, limit and offset. No support for joins, aggregates or mutations.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7840
GitOrigin-RevId: 3f03b8416c95acf2b68da1db56cbe36a513a4bde
Hooks up event trigger codecs from #7237. This required fixing a problem where some backend types implemented `defaultTriggerOnReplication` with `error` which caused the server to crash when evaluating those for default values in codecs. The changes here add a type family to `Backend` called `XEventTriggers` that signals backend support for event triggers, and changes the type of `defaultTriggerOnReplication` to from `TriggerOnReplication` to `Maybe (XEventTriggers b, TriggerOnReplication)` so that it can only be implemented with a `Just` value if `XEventTriggers b` is inhabited. This emulates some existing type families in `Backend`. (Thanks to @daniel-chambers for this suggestion!)
I used the implementation of `defaultTriggerOnReplication` as a signal for event triggers support to prune the Metadata API so that event trigger fields will not appear in the OpenAPI spec for backend types that do not support event triggers. The codec version of the API will also not emit or accept those fields for those backend types. I think I could use `Typeable` to test whether `XEventTriggers` is `Void` instead of testing whether `defaultTriggerOnReplication` is `Nothing`. But the codec implementation will crash anyway if `defaultTriggerOnReplication` is `Nothing`.
I checked to make sure that graphql-engine-pro still compiles.
Ticket: https://hasurahq.atlassian.net/browse/GDC-521
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7295
GitOrigin-RevId: 2b2dd44291513266107ca25cf330319bf53a8b66
## Description
There is a bug in the metadata defaults code, see [the original PR](https://github.com/hasura/graphql-engine-mono/pull/6286).
Steps to reproduce this issue:
* Start a new HGE project
* Start HGE with a defaults argument: `HASURA_GRAPHQL_LOG_LEVEL=debug cabal run exe:graphql-engine -- serve --enable-console --console-assets-dir=./console/static/dist --metadata-defaults='{"backend_configs": {"dataconnector": {"mongo": {"display_name": "BONGOBB", "uri": "http://localhost:8123"}}}}'`
* Add a source (doesn't need to be related to the defaults)
* Export metadata
* See that the defaults are present in the exported metadata
## Related Issues
* Github Issue: https://github.com/hasura/graphql-engine/issues/9237
* Jira: https://hasurahq.atlassian.net/browse/GDC-647
* Original PR: https://github.com/hasura/graphql-engine-mono/pull/6286
## Solution
* The test for if defaults should be included for metadata api operations has been extended to check for updates
* Metadata inconsistencies have been hidden for `/capabilities` calls on startup
## TODO
* [x] Fix bug
* [x] Write tests
* [x] OSS Metadata Migration to correct persisted data - `server/src-rsr/migrations/47_to_48.sql`
* [x] Cloud Metadata Migration - `pro/server/res/cloud/migrations/6_to_7.sql`
* [x] Bump Catalog Version - `server/src-rsr/catalog_version.txt`
* [x] Update Catalog Versions - `server/src-rsr/catalog_versions.txt` (This will be done by Infra when creating a release)
* [x] Log connection error as it occurs *(Already being logged. Requires `--enabled-log-types startup,webhook-log,websocket-log,http-log,data-connector-log`)
* [x] Don't mark metadata inconsistencies for this call.
## Questions
* [ ] Does the `pro/server/res/cloud/migrations/6_to_7.sql` cover the cloud scenarios?
* [ ] Should we have `SET search_path` in migrations?
* [x] What should be in `server/src-rsr/catalog_versions.txt`?
## Testing
To test the solution locally run:
> docker compose up -d
and
> cabal run -- exe:api-tests --skip BigQuery --skip SQLServer --skip '/Test.API.Explain/Postgres/'
## Solution
In `runMetadataQuery` in `server/src-lib/Hasura/Server/API/Metadata.hs`:
```diff
- if (exportsMetadata _rqlMetadata)
+ if (exportsMetadata _rqlMetadata || queryModifiesMetadata _rqlMetadata)
```
This ensures that defaults aren't present in operations that serialise metadata.
Note: You might think that `X_add_source` would need the defaults to be present to add a source that references the defaults, but since the resolution occurs in the schema-cache building phase, the defaults can be excluded for the metadata modifications required for `X_add_source`.
In addition to the code-change, a metadata migration has been introduced in order to clean up serialised defaults.
The following scenarios need to be considered for both OSS and Cloud:
* The user has not had defaults serialised
* The user has had the defaults serialised and no other backends configured
* The user has had the defaults serialised and has also configured other backends
We want to remove as much of the metadata as possible without any user-specified data and this should be reflected in migration `server/src-rsr/migrations/47_to_48.sql`.
## Server checklist
### Catalog upgrade
Does this PR change Hasura Catalog version?
- ✅ Yes
### Metadata
Does this PR add a new Metadata feature?
- ✅ No
### GraphQL
- ✅ No new GraphQL schema is generated
### Breaking changes
- ✅ No Breaking changes
## Changelog
__Component__ : server
__Type__: bugfix
__Product__: community-edition
### Short Changelog
Fixes a metadata defaults serialization bug and introduces a metadata migration to correct data that has been persisted due to the bug.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7034
GitOrigin-RevId: ad7d4f748397a1a607f2c0c886bf0fbbc3f873f2
## Description ✍️
This PR introduces a new feature to enable/disable event triggers during logical replication of table data for PostgreSQL and MS-SQL data sources. We introduce a new field `trigger_on_replication` in the `*_create_event_trigger` metadata API. By default the event triggers will not fire for logical data replication.
## Changelog ✍️
__Component__ : server
__Type__: feature
__Product__: community-edition
### Short Changelog
Add option to enable/disable event triggers on logically replicated tables
### Related Issues ✍
https://github.com/hasura/graphql-engine/issues/8814https://hasurahq.atlassian.net/browse/GS-252
### Solution and Design
- By default, triggers do **not** fire when the session mode is `replica` in Postgres, so if the `triggerOnReplication` is set to `true` for an event trigger we run the query `ALTER TABLE #{tableTxt} ENABLE ALWAYS TRIGGER #{triggerNameTxt};` so that the trigger fires always irrespective of the `session_replication_role`
- By default, triggers do fire in case of replication in MS-SQL, so if the `triggerOnReplication` is set to `false` for an event trigger we add a clause `NOT FOR REPLICATION` to the the SQL when the trigger is created/altered, which sets the `is_not_for_replication` for the trigger as `true` and it does not fire during logical replication.
### Steps to test and verify ✍
- Run hspec integration tests for HGE
## Server checklist ✍
### Metadata ✍
Does this PR add a new Metadata feature?
- ✅ Yes
- Does `export_metadata`/`replace_metadata` supports the new metadata added?
- ✅
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6953
Co-authored-by: Puru Gupta <32328846+purugupta99@users.noreply.github.com>
Co-authored-by: Sean Park-Ross <94021366+seanparkross@users.noreply.github.com>
GitOrigin-RevId: 92731328a2bbdcad2302c829f26f9acb33c36135
What is the `Cacheable` type class about?
```haskell
class Eq a => Cacheable a where
unchanged :: Accesses -> a -> a -> Bool
default unchanged :: (Generic a, GCacheable (Rep a)) => Accesses -> a -> a -> Bool
unchanged accesses a b = gunchanged (from a) (from b) accesses
```
Its only method is an alternative to `(==)`. The added value of `unchanged` (and the additional `Accesses` argument) arises _only_ for one type, namely `Dependency`. Indeed, the `Cacheable (Dependency a)` instance is non-trivial, whereas every other `Cacheable` instance is completely boilerplate (and indeed either generated from `Generic`, or simply `unchanged _ = (==)`). The `Cacheable (Dependency a)` instance is the only one where the `Accesses` argument is not just passed onwards.
The only callsite of the `unchanged` method is in the `ArrowCache (Rule m)` method. That is to say that the `Cacheable` type class is used to decide when we can re-use parts of the schema cache between Metadata operations.
So what is the `Cacheable (Dependency a)` instance about? Normally, the output of a `Rule m a b` is re-used when the new input (of type `a`) is equal to the old one. But sometimes, that's too coarse: it might be that a certain `Rule m a b` only depends on a small part of its input of type `a`. A `Dependency` allows us to spell out what parts of `a` are being depended on, and these parts are recorded as values of types `Access a` in the state `Accesses`.
If the input `a` changes, but not in a way that touches the recorded `Accesses`, then the output `b` of that rule can be re-used without recomputing.
So now you understand _why_ we're passing `Accesses` to the `unchanged` method: `unchanged` is an equality check in disguise that just needs some additional context.
But we don't need to pass `Accesses` as a function argument. We can use the `reflection` package to pass it as type-level context. So the core of this PR is that we change the instance declaration from
```haskell
instance (Cacheable a) => Cacheable (Dependency a) where
```
to
```haskell
instance (Given Accesses, Eq a) => Eq (Dependency a) where
```
and use `(==)` instead of `unchanged`.
If you haven't seen `reflection` before: it's like a `MonadReader`, but it doesn't require a `Monad`.
In order to pass the current `Accesses` value, instead of simply passing the `Accesses` as a function argument, we need to instantiate the `Given Accesses` context. We use the `give` method from the `reflection` package for that.
```haskell
give :: forall r. Accesses -> (Given Accesses => r) -> r
unchanged :: (Given Accesses => Eq a) => Accesses -> a -> a -> Bool
unchanged accesses a b = give accesses (a == b)
```
With these three components in place, we can delete the `Cacheable` type class entirely.
The remainder of this PR is just to remove the `Cacheable` type class and its instances.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6877
GitOrigin-RevId: 7125f5e11d856e7672ab810a23d5bf5ad176e77f
### Description
This monster of a PR took way too long. As the title suggests, it reduces the schema context carried in the readers to the very strict minimum. In practice, that means that to build a source, we only require:
- the global `SchemaContext`
- the global `SchemaOptions` (soon to be renamed `SchemaSourceOptions`)
- that source's `SourceInfo`
Furthermore, _we no longer carry "default" customization options throughout the schema_. All customization information is extracted from the `SourceInfo`, when required. This prevents an entire category of bugs we had previously encountered, such as parts of the code using uninitialized / unupdated customization info.
In turn, this meant that we could remove the explicit threading of the `SourceInfo` throughout the schema, since it is now always available through the reader context.
Finally, this meant making a few adjustments to relay and actions as well, such as the introduction of a new separate "context" for actions, and a change to how we create some of the action-specific postgres scalar parsers.
I'll highlight with review comments the areas of interest.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6709
GitOrigin-RevId: ea80fddcb24e2513779dd04b0b700a55f0028dd1
`CollectedInfo` was just an awkward sum type. By using an explicit `Either` instead, we can guarantee at the type level that certain methods only write inconsistencies, or only write dependencies. This is useful, because if we can guarantee that no dependencies are written, then we don't need to run `resolveDependencies` on that part of the Metadata. In other words, we can keep it out of `BuildOutputs`, which greatly benefits performance - see e.g. hasura/graphql-engine-mono#6613.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6765
GitOrigin-RevId: 9ce099d2eee2278dbb6e5bea72063e4b6e064b35
This upgrades the version of Ormolu required by the HGE repository to v0.5.0.1, and reformats all code accordingly.
Ormolu v0.5 reformats code that uses infix operators. This is mostly useful, adding newlines and indentation to make it clear which operators are applied first, but in some cases, it's unpleasant. To make this easier on the eyes, I had to do the following:
* Add a few fixity declarations (search for `infix`)
* Add parentheses to make precedence clear, allowing Ormolu to keep everything on one line
* Rename `relevantEq` to `(==~)` in #6651 and set it to `infix 4`
* Add a few _.ormolu_ files (thanks to @hallettj for helping me get started), mostly for Autodocodec operators that don't have explicit fixity declarations
In general, I think these changes are quite reasonable. They mostly affect indentation.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6675
GitOrigin-RevId: cd47d87f1d089fb0bc9dcbbe7798dbceedcd7d83
>
## Description
->
This PR allows DC agents to define custom aggregate functions for their scalar types.
### Related Issues
->
GDC-189
### Solution and Design
>
We added a new property `aggregate_functions` to the scalar types capabilities. This allows the agent author to specify a set of aggregate functions supported by each scalar type, along with the function's result type.
During GraphQL schema generation, the custom aggregate functions are available via a new method `getCustomAggregateOperators` on the `Backend` type class.
Custom functions are merged with the builtin aggregate functions when building GraphQL schemas for table aggregate fields and for `order_by` operators on array relations.
### Steps to test and verify
>
• Codec tests for aggregate function capabilities have been added to the unit tests.
• Some custom aggregate operators have been added to the reference agent and are used in a new test in `api-tests`.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6199
GitOrigin-RevId: e9c0d1617af93847c1493671fdbb794f573bde0c
This upgrades CI and anyone using Nix to HLint v3.4.1.
If you're not using Nix, this doesn't actually _do_ anything on your
local machine; it's just a suggestion.
It also applies a bunch of simple HLint refactors, using
`make lint-hs-fix`.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6324
GitOrigin-RevId: de8267e4909d6dcd3f83543188517f3aaeebc5f3
This PR is the result of running the following commands:
```bash
$ git grep -l '".* : "' -- '*.hs' | xargs sed -i -E 's/(".*) : "/\1: "/'
$ scripts/dev.sh test --integration --accept
```
Also manually fixed a few tests and docs
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6148
GitOrigin-RevId: cf8b87605d41d9ce86613a41ac5fd18691f5a641
The intent is to generalize `columnParser` to the point where it is the same across all backends, and then remove the interface in favor of a single implementation.
This extracts out `enumParser` and `possiblyNullable` as the two main areas that differ across backends. We may split `possiblyNullable` further so that we can extract some of that logic out into a common function too.
With these changes, the various `columnParser` implementations become semantically equivalent. They still do different things, and so reconciling them will require further changes.
Co-Authored-By: Antoine Leblanc <antoine@hasura.io>
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5841
GitOrigin-RevId: eec1770931eed5d72da70c97d7d0f00e33fa15d2
### Description
This PR changes all the schema code to operate in a specific `SchemaT` monad, rather than in an arbitrary `m` monad. `SchemaT` is intended to be used opaquely with `runSourceSchema` and `runRemoteSchema`. The main goal of this is to allow a different reader context per part of the schema: this PR also minimizes the contexts. This means that we no longer require `SchemaOptions` when building remote schemas' schema, and this PR therefore removes a lot of dummy / placeholder values accordingly.
### Performance and stacking
This PR has been through several iterations. #5339 was the original version, that accomplished the same thing by stacking readers on top of the stack at every remote relationship boundary. This raised performance concerns, and @0x777 confirmed with an ad-hoc test that in some extreme cases we could see up to a 10% performance impact. This version, while more verbose, allows us to unstack / re-stack the readers, and avoid that problem. #5517 adds a new benchmark set to be able to automatically measure this on every PR.
### Remaining work
- [x] a comment (or perhaps even a Note?) should be added to `SchemaT`
- [x] we probably want for #5517 to be merged first so that we can confirm the lack of performance penalty
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5458
GitOrigin-RevId: e06b83d90da475f745b838f1fd8f8b4d9d3f4b10
This PR expands the OpenAPI specification generated for metadata to include separate definitions for `SourceMetadata` for each native database type, and for DataConnector.
For the most part the changes add `HasCodec` implementations, and don't modify existing code otherwise.
The generated OpenAPI spec can be used to generate TypeScript definitions that distinguish different source metadata types based on the value of the `kind` properly. There is a problem: because the specified `kind` value for a data connector source is any string, when TypeScript gets a source with a `kind` value of, say, `"postgres"`, it cannot unambiguously determine whether the source is postgres, or a data connector. For example,
```ts
function consumeSourceMetadata(source: SourceMetadata) {
if (source.kind === "postgres" || source.kind === "pg") {
// At this point TypeScript infers that `source` is either an instance
// of `PostgresSourceMetadata`, or `DataconnectorSourceMetadata`. It
// can't narrow further.
source
}
if (source.kind === "something else") {
// TypeScript infers that this `source` must be an instance of
// `DataconnectorSourceMetadata` because `source.kind` does not match
// any of the other options.
source
}
}
```
The simplest way I can think of to fix this would be to add a boolean property to the `SourceMetadata` type along the lines of `isNative` or `isDataConnector`. This could be a field that only exists in serialized data, like the metadata version field. The combination of one of the native database names for `kind`, and a true value for `isNative` would be enough for TypeScript to unambiguously distinguish the source kinds.
But note that in the current state TypeScript is able to reference the short `"pg"` name correctly!
~~Tests are not passing yet due to some discrepancies in DTO serialization vs existing Metadata serialization. I'm working on that.~~
The placeholders that I used for table and function metadata are not compatible with the ordered JSON serialization in use. I think the best solution is to write compatible codecs for those types in another PR. For now I have disabled some DTO tests for this PR.
Here are the generated [OpenAPI spec](https://github.com/hasura/graphql-engine-mono/files/9397333/openapi.tar.gz) based on these changes, and the generated [TypeScript client code](https://github.com/hasura/graphql-engine-mono/files/9397339/client-typescript.tar.gz) based on that spec.
Ticket: [MM-66](https://hasurahq.atlassian.net/browse/MM-66)
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5582
GitOrigin-RevId: e1446191c6c832879db04f129daa397a3be03f62
Followup to hasura/graphql-engine-mono#4713.
The `memoizeOn` method, part of `MonadSchema`, originally had the following type:
```haskell
memoizeOn
:: (HasCallStack, Ord a, Typeable a, Typeable b, Typeable k)
=> TH.Name
-> a
-> m (Parser k n b)
-> m (Parser k n b)
```
The reason for operating on `Parser`s specifically was that the `MonadSchema` effect would additionally initialize certain `Unique` values, which appear (nested in) the type of `Parser`.
hasura/graphql-engine-mono#518 changed the type of `memoizeOn`, to additionally allow memoizing `FieldParser`s. These also contained a `Unique` value, which was similarly initialized by the `MonadSchema` effect. The new type of `memoizeOn` was as follows:
```haskell
memoizeOn
:: forall p d a b
. (HasCallStack, HasDefinition (p n b) d, Ord a, Typeable p, Typeable a, Typeable b)
=> TH.Name
-> a
-> m (p n b)
-> m (p n b)
```
Note the type `p n b` of the value being memoized: by choosing `p` to be either `Parser k` or `FieldParser`, both can be memoized. Also note the new `HasDefinition (p n b) d` constraint, which provided a `Lens` for accessing the `Unique` value to be initialized.
A quick simplification is that the `HasCallStack` constraint has never been used by any code. This was realized in hasura/graphql-engine-mono#4713, by removing that constraint.
hasura/graphql-engine-mono#2980 removed the `Unique` value from our GraphQL-related types entirely, as their original purpose was never truly realized. One part of removing `Unique` consisted of dropping the `HasDefinition (p n b) d` constraint from `memoizeOn`.
What I didn't realize at the time was that this meant that the type of `memoizeOn` could be generalized and simplified much further. This PR finally implements that generalization. The new type is as follows:
```haskell
memoizeOn ::
forall a p.
(Ord a, Typeable a, Typeable p) =>
TH.Name ->
a ->
m p ->
m p
```
This change has a couple of consequences.
1. While constructing the schema, we often output `Maybe (Parser ...)`, to model that the existence of certain pieces of GraphQL schema sometimes depends on the permissions that a certain role has. The previous versions of `memoizeOn` were not able to handle this, as the only thing they could memoize was fully-defined (if not yet fully-evaluated) `(Field)Parser`s. This much more general API _would_ allow memoizing `Maybe (Parser ...)`s. However, we probably have to be continue being cautious with this: if we blindly memoize all `Maybe (Parser ...)`s, the resulting code may never be able to decide whether the value is `Just` or `Nothing` - i.e. it never commits to the existence-or-not of a GraphQL schema fragment. This would manifest as a non-well-founded knot tying, and this would get reported as an error by the implementation of `memoizeOn`.
tl;dr: This generalization _technically_ allows for memoizing `Maybe` values, but we probably still want to avoid doing so.
For this reason, the PR adds a specialized version of `memoizeOn` to `Hasura.GraphQL.Schema.Parser`.
2. There is no longer any need to connect the `MonadSchema` knot-tying effect with the `MonadParse` effect. In fact, after this PR, the `memoizeOn` method is completely GraphQL-agnostic, and so we implement hasura/graphql-engine-mono#4726, separating `memoizeOn` from `MonadParse` entirely - `memoizeOn` can be defined and implemented as a general Haskell typeclass method.
Since `MonadSchema` has been made into a single-type-parameter type class, it has been renamed to something more general, namely `MonadMemoize`. Its only task is to memoize arbitrary `Typeable p` objects under a combined key consisting of a `TH.Name` and a `Typeable a`.
Also for this reason, the new `MonadMemoize` has been moved to the more general `Control.Monad.Memoize`.
3. After this change, it's somewhat clearer what `memoizeOn` does: it memoizes an arbitrary value of a `Typeable` type. The only thing that needs to be understood in its implementation is how the manual blackholing works. There is no more semantic interaction with _any_ GraphQL code.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4725
Co-authored-by: Daniel Harvey <4729125+danieljharvey@users.noreply.github.com>
GitOrigin-RevId: 089fa2e82c2ce29da76850e994eabb1e261f9c92
### Description
By definition, root fields are at the root of the schema: only functions that craft root fields need to know about how to customize the name of root fields. However, the presence of `Has MkRootFieldName` in `MonadBuildSchemaBase` meant that the entirety of the schema building code was implicitly aware of / capable of altering root field names.
This PR removes this constraint, and moves it to the functions that do craft root fields. This has several upsides:
- it makes it more explicit where root fields are being crafted
- it prevents functions that should not use this from mistakenly applying it to non-root fields
- it simplifies the shared schema context
### Future work
- can we maybe pass this as an argument, instead of making it a required part of the context?
- ~~AFAICT, we only ever use `mempty` for it: is this actually dead code that we should actually just remove altogether?~~
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5235
GitOrigin-RevId: 4268751f3ab87ae8e03b6fe9e1efa1b096200027
Updates to the latest version of autodocodec and uses the new features, in particular `discriminatedUnionCodec`.
This allows us to remove the `ValueWrapper*` types and `sumTypeCodec`. Sum types are now encoded as discriminated unions.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5155
GitOrigin-RevId: 20bfdc12b28d35db354c4a149b9175fab0b2b7d2
This introduces an `ErrorMessage` newtype which wraps `Text` in a manner which is designed to be easy to construct, and difficult to deconstruct.
It provides functionality similar to `Data.Text.Extended`, but designed _only_ for error messages. Error messages are constructed through `fromString`, concatenation, or the `toErrorValue` function, which is designed to be overridden for all meaningful domain types that might show up in an error message. Notably, there are not and should never be instances of `ToErrorValue` for `String`, `Text`, `Int`, etc. This is so that we correctly represent the value in a way that is specific to its type. For example, all `Name` values (from the _graphql-parser-hs_ library) are single-quoted now; no exceptions.
I have mostly had to add `instance ToErrorValue` for various backend types (and also add newtypes where necessary). Some of these are not strictly necessary for this changeset, as I had bigger aspirations when I started. These aspirations have been tempered by trying and failing twice.
As such, in this changeset, I have started by introducing this type to the `parseError` and `parseErrorWith` functions. In the future, I would like to extend this to the `QErr` record and the various `throwError` functions, but this is a much larger task and should probably be done in stages.
For now, `toErrorMessage` and `fromErrorMessage` are provided for conversion to and from `Text`, but the intent is to stop exporting these once all error messages are converted to the new type.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5018
GitOrigin-RevId: 84b37e238992e4312255a87ca44f41af65e2d89a
This moves `MkTypename` and `NamingCase` into their own modules, with the intent of reducing the scope of the schema parsers code, and trying to reduce imports of large modules when small ones will do.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4978
GitOrigin-RevId: 19541257fe010035390f6183a4eaa37bae0d3ca1
