### Motivation
#2338 introduced a way to validate REST queries against the metadata after a change, to properly report any inconsistency that would emerge from a change in the underlying structure of our schema. However, the way this was done was quite complex and error-prone. Namely: we would use the generated schema parsers to statically execute an introspection query, similar to the one we use for remote schemas, then parse the resulting bytestring as it were coming from a remote schema.
This led to several issues: the code was using remote schema primitives, and was associated with remote schema code, despite being unrelated, which led to absurd situations like creating fake `Variable`s whose type was also their name. A lot of the code had to deal with the fact that we might fail to re-parse our own schema. Additionally, some of it was dead code, that for some reason GHC did not warn about? But more fundamentally, this architecture decision creates a dependency between unrelated pieces of the engine: modifying the internal processing of root fields or the introspection of remote schemas now risks impacting the unrelated `OpenAPI` feature.
### Description
This PR decouples that process from the remote schema introspection logic and from the execution engine by making `Analyse` and `OpenAPI` work on the generic `G.SchemaIntrospection` instead. To accomplish this, it:
- adds `GraphQL.Parser.Schema.Convert`, to convert from our "live" schema back to a flat `SchemaIntrospection`
- persists in the schema cache the `admin` introspection generated when building the schema, and uses it both for validation and for generating the `OpenAPI`.
### Known issues and limitations
This adds a bit of memory pressure to the engine, as we persist the entire schema in the schema cache. This might be acceptable in the short-term, but we have several potential ideas going forward should this be a problem:
- cache the result of `Analyze`: when it becomes possible to build the `OpenAPI` purely with the result of `Analyze` without any additional schema information, then we could cache that instead, reducing the footprint
- caching the `OpenAPI`: if it doesn't need to change every time the endpoint is queried, then it should be possible to cache the entire `OpenAPI` object instead of the schema
- cache a copy of the `FieldParsers` used to generate the schema: as those are persisted through the GraphQL `Context`, and are the only input required to generate the `Schema`, making them accessible in the schema cache would allow us to have the exact same feature with no additional memory cost, at the price of a slightly slower and more complicated process (need to rebuild the `Schema` every time we query the OpenAPI endpoint)
- cache nothing at all, and rebuild the admin schema from scratch every time.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3962
Co-authored-by: paritosh-08 <85472423+paritosh-08@users.noreply.github.com>
GitOrigin-RevId: a8b9808170b231fdf6787983b4a9ed286cde27e0
### Description
This is it! This PR enables the Metadata API for remote relationships from remote schemas, adds tests, ~~adds documentation~~, adds an entry to the Changelog. This is the release PR that enables the feature.
### Checklist
- [ ] Tests:
- [x] RS-to-Postgres (high level)
- [x] RS-to-RS (high level)
- [x] From RS specifically (testing for edge cases)
- [x] Metadata API tests
- [ ] Unit testing the actual engine?
- [x] Changelog entry
- [ ] Documentation?
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3974
Co-authored-by: Vamshi Surabhi <6562944+0x777@users.noreply.github.com>
Co-authored-by: Vishnu Bharathi <4211715+scriptnull@users.noreply.github.com>
Co-authored-by: jkachmar <8461423+jkachmar@users.noreply.github.com>
GitOrigin-RevId: c9aebf12e6eebef8d264ea831a327b968d4be9d2
In hasura/graphql-engine#5144, we noticed that having remote relationships in the schema is problematic for Relay. In particular, we don't support remote schemas in Relay at all, and because of this, remote relationships were also broken.
The fix was easy: when we're building the schema for Relay, whenever we encounter a remote relationship in our configuration, we simply skip building that field. The implementation was easy: (see hasura/graphql-engine#5145)
```diff
- SFRemoteRelationship info -> pure $ mkRemoteRelationshipFld info
+ SFRemoteRelationship info ->
+ -- https://github.com/hasura/graphql-engine/issues/5144
+ if isRelay then [] else pure $ mkRemoteRelationshipFld info
```
A test case was added in that PR to prevent us from accidentally re-including remote relationships in the Relay schema. (However, it now looks like that test case does not function correctly.)
The above code was later refactored in #3037, making use of the `MaybeT` effect. However, this effect was not used correctly, so that the result of the check was ignored.
This fixes the code to use the `MaybeT` effect correctly.
CC @0x777 @rakeshkky
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3868
GitOrigin-RevId: e528303e01eacf60173cba1eec1898986cf12359
Numbers from CI for the new (currently noisy) `replace_metadata` adhoc benchmark:
chinook: 0.19s -> 0.16
huge_schema: 36.98s -> 29.89
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3685
GitOrigin-RevId: be79b666858b03e8407c0d89765e9aac0af8d40a
In order to respond to GraphQL queries that make use of the introspection fields `__type` or `__schema`, we need two things:
- an overview of the relevant GraphQL type information, stored in a `Schema` object, and
- to have included the `__type` and `__schema` fields in the `query_root` that we generate.
It used to be necessary to do the above items in that order, since the `__type` and `__schema` fields (i.e. the respective `FieldParser`s) were generated _from_ a `Schema` object.
Thanks to recent refactorings in `Hasura.GraphQL.Schema.Introspect` (see hasura/graphql-engine-mono#2835 or hasura/graphql-engine@5760d9289c), the introspection fields _themselves_ are now `Schema`-agnostic, and simply return a function that takes a `Schema` object after parsing. For instance, the type of `schema`, corresponding to the `__schema` field, has literally changed as follows:
```diff
-schema :: MonadParse n => Schema -> FieldParser n ( J.Value)
+schema :: MonadParse n => FieldParser n (Schema -> J.Value)
```
This means that the introspection fields can be included in the GraphQL schema *before* we have generated a `Schema` object. In particular, rather than the current architecture of generating `Schema` at startup time for every role, we can instead generate `Schema` ad-hoc at query parsing time, only for those queries that make use of the introspection fields. This avoids us storing a `Schema` for every role for the lifetime of the server.
However: this introduces a functional change, as the code that generates the `Schema` object, and in particular the `accumulateTypeDefinitions` method, also does certain correctness checks, to prevent exposing a spec-incompliant GraphQL schema. If these correctness checks are being done at parsing time rather than startup time, then we catch certain errors only later on. For this reason, this PR adds an explicit run of this type accumulation at startup time. For efficiency reasons, and since this correctness check is not essential for correct operation of HGE, this is done for the admin role only.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3231
GitOrigin-RevId: 23701c548b785929b28667025436b6ce60bfe1cd
spec: https://github.com/hasura/graphql-engine-mono/pull/2278
Briefly:
- extend metadata so that allowlist entries get a new scope field
- update `add_collection_to_allowlist` to accept this new scope field,
and adds `update_scope_of_collection_in_allowlist` to change the scope
- scope can be global or role-based; a collection is available for every
role if it is global, and available to every listed role if it is role-based
- graphql-engine-oss is aware of role-based allowlist metadata; collections
with non-global scope are treated as if they weren't in the allowlist
To run the tests:
- `cabal run graphql-engine-tests -- unit --match Allowlist`
- py-tests against pro:
- launch `graphql-engine-pro` with `HASURA_GRAPHQL_ADMIN_SECRET` and `HASURA_GRAPHQL_ENABLE_ALLOWLIST`
- `pytest test_allowlist_queries.py --hge-urls=... --pg-urls=... --hge-key=... --test-allowlist-queries --pro-tests`
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2477
Co-authored-by: Anon Ray <616387+ecthiender@users.noreply.github.com>
Co-authored-by: Robert <132113+robx@users.noreply.github.com>
GitOrigin-RevId: 01f8026fbe59d8701e2de30986511a452fce1a99
### Description
The GraphQL spec has to conflicting requirements:
1. an object must contain at least one field: the schema may not contain empty objects
2. the _query_root_ must always be present
Given _1_, the schema generation code removes from the schema all fields that would result in empty objects, such as a table for which a user does not have select permissions. But, as a result, our code also potentially removes _query_root_ if it is empty, breaking _2_.
This PR introduces a dummy "placeholder" field in the query root if it's empty, to ensure we never remove it from the schema.
### Remaining work
- [x] changelog entry
- [x] tests
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/148
GitOrigin-RevId: bfd6bfcc2f3de92900b6ba566012f093399ca037
## Description
When setting up a remote relationship to a remote schema, values coming from the left-hand side are given as _arguments_ to the targeted field of the remote schema. In turn, that means we need to adjust the arguments to that remote field; in the case of input objects, it means creating a brand new input object in which the relevant fields have been removed.
To both avoid conflicts, and be explicit, we give a pretty verbose name to such an input object: its original name, followed by "remote_rel", followed by the full name of the field (table name + relationship name). The bug there was introduced when working on extending remote relationships to other backends: we changed the code that translates the table name to a graphql identifier to be generic, and use the table's `ToTxt` instance instead. However, when a table is not in the default schema, the character used by that instance is `.`, which is not a valid GraphQL name.
This PR fixes it, by doing two things:
- it defines a safe function to translate LHS identifiers to graphql names (by replacing all invalid characters by `_`)
- it doesn't use `unsafeMkName` anymore, and checks at validation time that the type name is correct
## Further work
On this PR:
- [x] add a test
- [x] write a Changelog entry
Beyond this PR, we might want to:
- prioritize #1747
- analyze all calls to `unsafeMkName` and remove as many as possible
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3363
GitOrigin-RevId: fe98eb1d34157b2c8323af453f5c369de616af38
## Description
I come across a flaky test due to inconsistent error messages from the odbc lib we use for MSSQL database interactions.
```
cabal new-run -- test:graphql-engine-tests mssql
Up to date
Database.MSSQL.TransactionSpec
runTx
runs command in a transaction
commits a successful transaction, returning a single field
commits a successful transaction, returning multiple fields
an unsuccesful transaction, expecting Int
a successfull query expecting multiple rows
an unsuccesful transaction; expecting single row
displays the SQL Server error on an unsuccessful transaction FAILED [1]
rolls back an unsuccessful transaction
Failures:
src-test/Database/MSSQL/TransactionSpec.hs:60:15:
1) Database.MSSQL.TransactionSpec.runTx displays the SQL Server error on an unsuccessful transaction
expected: UnsuccessfulReturnCode "odbc_SQLExecDirectW" (-1) "[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]The definition for column 'INVALID_SYNTAX' must include a data type.[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]The definition for column 'INVALID_SYNTAX' must include a data type."
but got: UnsuccessfulReturnCode "odbc_SQLExecDirectW" (-1) "[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]The definition for column 'INVALID_SYNTAX' must include a data type.[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]The definition for column 'INVALID_SYNTAX' must include a data type.\DEL"
To rerun use: --match "/Database.MSSQL.TransactionSpec/runTx/displays the SQL Server error on an unsuccessful transaction/"
Randomized with seed 1101559172
Finished in 0.2140 seconds
8 examples, 1 failure
```
From above, we got a error message with `\DEL` appended. It is also driving the tests to fail in the CI on random PRs.
We brought this into notice of "fpco", the authors of the library and they got us a [quick fix](https://github.com/fpco/odbc/pull/43), which also improves the errors by removing the redundancy of the error message.
In this PR
- We update the `odbc` library git reference to fc5b592a60
- Update the error messages in tests to conform with improved error messages from `odbc`
## Related issues
Closes https://github.com/hasura/graphql-engine-mono/issues/3340
## Changelog
- ✅ `CHANGELOG.md` is updated with user-facing content relevant to this PR.
## Affected components
- ✅ server
- ✅ tests
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3345
GitOrigin-RevId: a5694e8afb58b5ad71b9c9635a80dea1ec449f51
- Hasura CLI shows metadata diff in YAML for type `json` in directory mode. The expected behaviour is to show the diff in JSON
- The unified-json shows diff in YAML, not in JSON.
- Add new diff type unified-yaml which shows the diff in YAML unified format.
- Check the flag value of type in `hasura metadata diff --type`
- The help text of `seed apply`( `hasura seed apply --file seeds/1234_add_some_seed_data.sql`) should be updated to `hasura seed apply --file 1234_add_some_seed_data.sql --database-name default` and similarly in docs.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3246
Co-authored-by: Aravind K P <8335904+scriptonist@users.noreply.github.com>
GitOrigin-RevId: 1d16ad9ea4dd366af32498ce878ae132bd239be9
## Remaining Work
- [x] changelog entry
- [x] more tests: `<backend>_delete_remote_relationship` is definitely untested
- [x] negative tests: we probably want to assert that there are some APIs we DON'T support
- [x] update the console to use the new API, if necessary
- [x] ~~adding the corresponding documentation for the API for other backends (only `pg_` was added here)~~
- deferred to https://github.com/hasura/graphql-engine-mono/issues/3170
- [x] ~~deciding which backends should support this API~~
- deferred to https://github.com/hasura/graphql-engine-mono/issues/3170
- [x] ~~deciding what to do about potentially overlapping schematic representations~~
- ~~cf. https://github.com/hasura/graphql-engine-mono/pull/3157#issuecomment-995307624~~
- deferred to https://github.com/hasura/graphql-engine-mono/issues/3171
- [x] ~~add more descriptive versioning information to some of the types that are changing in this PR~~
- cf. https://github.com/hasura/graphql-engine-mono/pull/3157#discussion_r769830920
- deferred to https://github.com/hasura/graphql-engine-mono/issues/3172
## Description
This PR fixes several important issues wrt. the remote relationship API.
- it fixes a regression introduced by [#3124](https://github.com/hasura/graphql-engine-mono/pull/3124), which prevented `<backend>_create_remote_relationship` from accepting the old argument format (break of backwards compatibility, broke the console)
- it removes the command `create_remote_relationship` added to the v1/metadata API as a work-around as part of [#3124](https://github.com/hasura/graphql-engine-mono/pull/3124)
- it reverts the subsequent fix in the console: [#3149](https://github.com/hasura/graphql-engine-mono/pull/3149)
Furthermore, this PR also addresses two other issues:
- THE DOCUMENTATION OF THE METADATA API WAS WRONG, and documented `create_remote_relationship` instead of `<backend>_create_remote_relationship`: this PR fixes this by adding `pg_` everywhere, but does not attempt to add the corresponding documentation for other backends, partly because:
- `<backend>_delete_remote_relationship` WAS BROKEN ON NON-POSTGRES BACKENDS; it always expected an argument parameterized by Postgres.
As of main, the `<backend>_(create|update|delete)_remote_relationship` commands are supported on Postgres, Citus, BigQuery, but **NOT MSSQL**. I do not know if this is intentional or not, if it even should be publicized or not, and as a result this PR doesn't change this.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3157
Co-authored-by: jkachmar <8461423+jkachmar@users.noreply.github.com>
GitOrigin-RevId: 37e2f41522a9229a11c595574c3f4984317d652a
## Description
This PR fixes two issues:
- in [#2903](https://github.com/hasura/graphql-engine-mono/pull/2903), we introduced a new metadata representation of remote relationships, which broke parsing a metadata blob containing an old-style db-to-rs remote relationship
- in [#1179](https://github.com/hasura/graphql-engine-mono/pull/1179), we silently and mistakenly deprecated `create_remote_relationship` in favour of `<backend>_create_remote_relationship`
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3124
Co-authored-by: jkachmar <8461423+jkachmar@users.noreply.github.com>
Co-authored-by: Antoine Leblanc <1618949+nicuveo@users.noreply.github.com>
GitOrigin-RevId: 45481db7a8d42c7612e938707cd2d652c4c81bf8
### Description
This PR changes the internal representation of a parsed remote schema. We were still using a list of type definitions, meaning every time we were doing a type lookup we had to iterate through a linked list! 🙀 It was very noticeable on large schemas, that need to do a lot of lookups. This PR consequently changes the internal representation to a HashMap. Building the OneGraph schema on my machine now takes **23 seconds**, compared to **367 seconds** before this patch.
Some important points:
- ~~this PR removes a check for type duplication in remote schemas; it's unclear to me whether that's something we need to add back or not~~ (no longer true)
- this PR makes it obvious that we do not distinguish between "this remote schema is missing type X" and "this remote schema expects type X to be an object, but it's a scalar"; this PR doesn't change anything about it, but adds a comment where we could surface that error (see [2991](https://github.com/hasura/graphql-engine-mono/issues/2991))
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2963
GitOrigin-RevId: f5c96ad40f4e0afcf8cef635b4d64178111f98d3
>
High-Level TODO:
* [x] Code Changes
* [x] Tests
* [x] Check that pro/multitenant build ok
* [x] Documentation Changes
* [x] Updating this PR with full details
* [ ] Reviews
* [ ] Ensure code has all FIXMEs and TODOs addressed
* [x] Ensure no files are checked in mistakenly
* [x] Consider impact on console, cli, etc.
### Description
>
This PR adds support for adding set-cookie header on the response from the auth webhook. If the set-cookie header is sent by the webhook, it will be forwarded in the graphQL engine response.
Fixes a bug in test-server.sh: testing of get-webhook tests was done by POST method and vice versa. To fix, the parameters were swapped.
### Changelog
- [x] `CHANGELOG.md` is updated with user-facing content relevant to this PR.
### Affected components
- [x] Server
- [ ] Console
- [ ] CLI
- [x] Docs
- [ ] Community Content
- [ ] Build System
- [x] Tests
- [ ] Other (list it)
### Related Issues
->
Closes [#2269](https://github.com/hasura/graphql-engine/issues/2269)
### Solution and Design
>
### Steps to test and verify
>
Please refer to the docs to see how to send the set-cookie header from webhook.
### Limitations, known bugs & workarounds
>
- Support for only set-cookie header forwarding is added
- the value forwarded in the set-cookie header cannot be validated completely, the [Cookie](https://hackage.haskell.org/package/cookie) package has been used to parse the header value and any unnecessary information is stripped off before forwarding the header. The standard given in [RFC6265](https://datatracker.ietf.org/doc/html/rfc6265) has been followed for the Set-Cookie format.
### Server checklist
#### Catalog upgrade
Does this PR change Hasura Catalog version?
- [x] No
- [ ] Yes
- [ ] Updated docs with SQL for downgrading the catalog
#### Metadata
Does this PR add a new Metadata feature?
- [x] No
#### GraphQL
- [x] No new GraphQL schema is generated
- [ ] New GraphQL schema is being generated:
- [ ] New types and typenames are correlated
#### Breaking changes
- [x] No Breaking changes
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2538
Co-authored-by: Robert <132113+robx@users.noreply.github.com>
GitOrigin-RevId: d9047e997dd221b7ce4fef51911c3694037e7c3f
<!-- Thank you for ss in the Title above ^ -->
## Description
<!-- Please fill thier. -->
<!-- Describe the changes from a user's perspective -->
We don't have dependency reporting mechanism for `mssql_run_sql` API i.e when a database object (table, column etc.) is dropped through the API we should raise an exception if any dependencies (relationships, permissions etc.) with the database object exists in the metadata.
This PR addresses the above mentioned problem by
-> Integrating transaction to the API to rollback the SQL query execution if dependencies exists and exception is thrown
-> Accepting `cascade` optional field in the API payload to drop the dependencies, if any
-> Accepting `check_metadata_consistency` optional field to bypass (if value set to `false`) the dependency check
### Related Issues
<!-- Please make surt title -->
<!-- Add the issue number below (e.g. #234) -->
Close#1853
### Solution and Design
<!-- How is this iss -->
<!-- It's better if we elaborate -->
The design/solution follows the `run_sql` API implementation for Postgres backend.
### Steps to test and verify
<!-- If this is a fehis is a bug-fix, how do we verify the fix? -->
- Create author - article tables and track them
- Defined object and array relationships
- Try to drop the article table without cascade or cascade set to `false`
- The server should raise the relationship dependency exists exception
## Changelog
- ✅ `CHANGELOG.md` is updated with user-facing content relevant to this PR.
If no changelog is required, then add the `no-changelog-required` label.
## Affected components
<!-- Remove non-affected components from the list -->
- ✅ Server
- ❎ Console
- ❎ CLI
- ❎ Docs
- ❎ Community Content
- ❎ Build System
- ✅ Tests
- ❎ Other (list it)
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2636
GitOrigin-RevId: 0ab152295394056c4ca6f02923142a1658ad25dc
Prior to this change, the SQL expression that resulted from translating permissions on functions would refer to the table of the function's return type, rather than the set of rows selected from the function being called.
Now the SQL that results from translating permissions correctly refer to the selected rows.
This PR also contains the suggested additions of https://github.com/hasura/graphql-engine-mono/pull/2563#discussion_r726116863, which simplifies the Boolean Expression IR, but in turn makes the Schema Dependency Discovery algorithm work a bit harder.
We are changing the definition of `data OpExpG`, but the format accepted by its JSON parser remains unchanged. While there does exist a generically derived `instance ToJSON OpExpG` this is only used in the (unpublished) `/v1/metadata/dump_internal_state` API.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2609
Co-authored-by: Gil Mizrahi <8547573+soupi@users.noreply.github.com>
GitOrigin-RevId: bb9a0b4addbc239499dd2268909220196984df72
>
### Description
>
Insert mutations for MSSQL backend. This PR implements execution logic.
### Changelog
- [x] `CHANGELOG.md` is updated with user-facing content relevant to this PR. If no changelog is required, then add the `no-changelog-required` label.
### Affected components
- [x] Server
- [x] Tests
### Related Issues
->
Close https://github.com/hasura/graphql-engine-mono/issues/2114
### Steps to test and verify
>
Track a MSSQL table and perform the generated insert mutation to test.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2248
Co-authored-by: Abby Sassel <3883855+sassela@users.noreply.github.com>
Co-authored-by: Philip Lykke Carlsen <358550+plcplc@users.noreply.github.com>
GitOrigin-RevId: 936f138c80d7a928180e6e7b0c4da64ecc1f7ebc
Issue: https://github.com/hasura/graphql-engine/issues/7499
Problem: cli doesn't exit if `migrate apply --all-databases` fail on 1 or more databases
Solution: Store the names of the databases for which it failed and return
```
operation failed on : <database1>,<database2>,etc
```
https://github.com/hasura/graphql-engine-mono/pull/2305
Co-authored-by: Aravind K P <8335904+scriptonist@users.noreply.github.com>
Co-authored-by: Vijay Prasanna <11921040+vijayprasanna13@users.noreply.github.com>
GitOrigin-RevId: 8a30bdcc24de8a204320b00e5ea9d593a6293ad4
Issue: https://github.com/hasura/graphql-engine/issues/7510
Problem:
- To mark the migration applied after creating the migration from the server with skip-execution flag
Solution:
After creating migration apply it with skip-execution true
https://github.com/hasura/graphql-engine-mono/pull/2333
Co-authored-by: Aravind K P <8335904+scriptonist@users.noreply.github.com>
GitOrigin-RevId: 72eca352b76afe3a19d2198169b31284e38af07a
>
### Description
>
While adding [insert mutation schema parser for MSSQL backend](https://github.com/hasura/graphql-engine-mono/pull/2141) I also included [identity](https://en.wikipedia.org/wiki/Identity_column) notion to table columns across all backends. In MSSQL we cannot insert any value (even `DEFAULT` expression) into Identity columns. This behavior of identity columns is not same in Postgres as we can insert values. This PR drops the notion of identity in the column info. The context of identity columns for MSSQL is carried in `ExtraTableMetadata` type.
### Changelog
- [x] `CHANGELOG.md` is updated with user-facing content relevant to this PR. If no changelog is required, then add the `no-changelog-required` label.
### Affected components
- [x] Server
- [ ] Console
- [ ] CLI
- [ ] Docs
- [ ] Community Content
- [ ] Build System
- [x] Tests
- [ ] Other (list it)
### Related Issues
->
Fix https://github.com/hasura/graphql-engine/issues/7557https://github.com/hasura/graphql-engine-mono/pull/2378
GitOrigin-RevId: c18b5708e2e6107423a0a95a7fc2e9721e8a21a1
### Description
We always build a subscription root, even when there was no possible fields. This breaks some third party clients, as the spec does not allow empty types in the schema. This PR fixes this by changing the `buildSubscriptionParser` helper to return a `Maybe` value, and harmonizes / cleans places where we build the subscription root.
https://github.com/hasura/graphql-engine-mono/pull/2357
GitOrigin-RevId: 1aeae25e321eee957e7645c436d17e69207309fd
