## Description
This change adds support for querying into nested arrays in Data Connector agents that support such a concept (currently MongoDB).
### DC API changes
- New API type `ColumnType` which allows representing the type of a "column" as either a scalar type, an object reference or an array of `ColumnType`s. This recursive definition allows arbitrary nesting of arrays of types.
- The `type` fields in the API types `ColumnInfo` and `ColumnInsertSchema` now take a `ColumnType` instead of a `ScalarType`.
- To ensure backwards compatibility, a `ColumnType` representing a scalar serialises and deserialises to the same representation as `ScalarType`.
- In queries, the `Field` type now has a new constructor `NestedArrayField`. This contains a nested `Field` along with optional `limit`, `offset`, `where` and `order_by` arguments. (These optional arguments are not yet used by either HGE or the MongoDB agent.)
### MongoDB Haskell agent changes
- The `/schema` endpoint will now recognise arrays within the JSON validation schema and generate corresponding arrays in the DC schema.
- The `/query` endpoint will now handle `NestedArrayField`s within queries (although it does not yet handle `limit`, `offset`, `where` and `order_by`).
### HGE server changes
- The `Backend` type class adds a new type family `XNestedArrays b` to enable nested arrays on a per-backend basis (currently enabled only for the `DataConnector` backend.
- Within `RawColumnInfo` the column type is now represented by a new type `RawColumnType b` which mirrors the shape of the DC API `ColumnType`, but uses `XNestedObjects b` and `XNestedArrays b` type families to allow turning nested object and array supports on or off for a particular backend. In the `DataConnector` backend `API.CustomType` is converted into `RawColumnInfo 'DataConnector` while building the schema.
- In the next stage of schema building, the `RawColumnInfo` is converted into a `StructuredColumnInfo` which allows us to represent the three different types of columns: scalar, object and array. TODO: the `StructuredColumnInfo` looks very similar to the Logical Model types. The main difference is that it uses the `XNestedObjects` and `XNestedArrays` type families. We should be able to combine these two representations.
- The `StructuredColumnInfo` is then placed into a `FIColumn` `FieldInfo`. This involved some refactoring of `FieldInfo` as I had previously split out `FINestedObject` into a separate constructor. However it works out better to represent all "column" fields (i.e. scalar, object and array) using `FIColumn` as this make it easier to implement permission checking correctly. This is the reason the `StructuredColumnInfo` was needed.
- Next, the `FieldInfo` are used to generate `FieldParser`s. We add a new constructor to `AnnFieldG` for `AFNestedArray`. An `AFNestedArray` field parser can contain either a simple array selection or an array aggregate. Simple array `FieldParsers` are currently limited to subfield selection. We will add support for limit, offset, where and order_by in a future PR. We also don't yet generate array aggregate `FieldParsers.
- The new `AFNestedArray` field is handled by the `QueryPlan` module in the `DataConnector` backend. There we generate an `API.NestedArrayField` from the AFNestedArray. We also handle nested arrays when reshaping the response from the DC agent.
## Limitations
- Support for limit, offset, filter (where) and order_by is not yet fully implemented, although it should not be hard to add this
- Support for aggregations on nested arrays is not yet fully implemented
- Permissions involving nested arrays (and objects) not yet implemented
- This should be integrated with Logical Model types, but that will happen in a separate PR
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9149
GitOrigin-RevId: 0e7b71a994fc1d2ca1ef73bfe7b96e95b5328531
This fixes the simple HLint warnings, and adds a few suppressions to avoid noise.
The suppressions don't really solve the problems, but I think the warnings here are quite benign and I'm uncomfortable with how likely I would be to introduce a bug during refactoring.
In the case of _pg-client_ and _resource-pool_, we can't use the recommended functions anyway, and there doesn't seem to be a way to tell HLint to ignore entire packages.
I have updated the `make` targets to only fail if errors or warnings are found, not suggestions. This brings it in line with the CI job.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/8910
GitOrigin-RevId: 596277b4ae5833876fc3f43875208c1279518a59
## Description
This change adds support for nested object fields in HGE IR and Schema Cache, the Data Connectors backend and API, and the MongoDB agent.
### Data Connector API changes
- The `/schema` endpoint response now includes an optional set of GraphQL type definitions. Table column types can refer to these definitions by name.
- Queries can now include a new field type `object` which contains a column name and a nested query. This allows querying into a nested object within a field.
### MongoDB agent changes
- Add support for querying into nested documents using the new `object` field type.
### HGE changes
- The `Backend` type class has a new type family `XNestedObjects b` which controls whether or not a backend supports querying into nested objects. This is currently enabled only for the `DataConnector` backend.
- For backends that support nested objects, the `FieldInfo` type gets a new constructor `FINestedObject`, and the `AnnFieldG` type gets a new constructor `AFNestedObject`.
- If the DC `/schema` endpoint returns any custom GraphQL type definitions they are stored in the `TableInfo` for each table in the source.
- During schema cache building, the function `addNonColumnFields` will check whether any column types match custom GraphQL object types stored in the `TableInfo`. If so, they are converted into `FINestedObject` instead of `FIColumn` in the `FieldInfoMap`.
- When building the `FieldParser`s from `FieldInfo` (function `fieldSelection`) any `FINestedObject` fields are converted into nested object parsers returning `AFNestedObject`.
- The `DataConnector` query planner converts `AFNestedObject` fields into `object` field types in the query sent to the agent.
## Limitations
### HGE not yet implemented:
- Support for nested arrays
- Support for nested objects/arrays in mutations
- Support for nested objects/arrays in order-by
- Support for filters (`where`) in nested objects/arrays
- Support for adding custom GraphQL types via track table metadata API
- Support for interface and union types
- Tests for nested objects
### Mongo agent not yet implemented:
- Generate nested object types from validation schema
- Support for aggregates
- Support for order-by
- Configure agent port
- Build agent in CI
- Agent tests for nested objects and MongoDB agent
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7844
GitOrigin-RevId: aec9ec1e4216293286a68f9b1af6f3f5317db423
### 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
>
## 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
The main aim of the PR is:
1. To set up a module structure for 'remote-schemas' package.
2. Move parts by the remote schema codebase into the new module structure to validate it.
## Notes to the reviewer
Why a PR with large-ish diff?
1. We've been making progress on the MM project but we don't yet know long it is going to take us to get to the first milestone. To understand this better, we need to figure out the unknowns as soon as possible. Hence I've taken a stab at the first two items in the [end-state](https://gist.github.com/0x777/ca2bdc4284d21c3eec153b51dea255c9) document to figure out the unknowns. Unsurprisingly, there are a bunch of issues that we haven't discussed earlier. These are documented in the 'open questions' section.
1. The diff is large but that is only code moved around and I've added a section that documents how things are moved. In addition, there are fair number of PR comments to help with the review process.
## Changes in the PR
### Module structure
Sets up the module structure as follows:
```
Hasura/
RemoteSchema/
Metadata/
Types.hs
SchemaCache/
Types.hs
Permission.hs
RemoteRelationship.hs
Build.hs
MetadataAPI/
Types.hs
Execute.hs
```
### 1. Types representing metadata are moved
Types that capture metadata information (currently scattered across several RQL modules) are moved into `Hasura.RemoteSchema.Metadata.Types`.
- This new module only depends on very 'core' modules such as
`Hasura.Session` for the notion of roles and `Hasura.Incremental` for `Cacheable` typeclass.
- The requirement on database modules is avoided by generalizing the remote schemas metadata to accept an arbitrary 'r' for a remote relationship
definition.
### 2. SchemaCache related types and build logic have been moved
Types that represent remote schemas information in SchemaCache are moved into `Hasura.RemoteSchema.SchemaCache.Types`.
Similar to `H.RS.Metadata.Types`, this module depends on 'core' modules except for `Hasura.GraphQL.Parser.Variable`. It has something to do with remote relationships but I haven't spent time looking into it. The validation of 'remote relationships to remote schema' is also something that needs to be looked at.
Rips out the logic that builds remote schema's SchemaCache information from the monolithic `buildSchemaCacheRule` and moves it into `Hasura.RemoteSchema.SchemaCache.Build`. Further, the `.SchemaCache.Permission` and `.SchemaCache.RemoteRelationship` have been created from existing modules that capture schema cache building logic for those two components.
This was a fair amount of work. On main, currently remote schema's SchemaCache information is built in two phases - in the first phase, 'permissions' and 'remote relationships' are ignored and in the second phase they are filled in.
While remote relationships can only be resolved after partially resolving sources and other remote schemas, the same isn't true for permissions. Further, most of the work that is done to resolve remote relationships can be moved to the first phase so that the second phase can be a very simple traversal.
This is the approach that was taken - resolve permissions and as much as remote relationships information in the first phase.
### 3. Metadata APIs related types and build logic have been moved
The types that represent remote schema related metadata APIs and the execution logic have been moved to `Hasura.RemoteSchema.MetadataAPI.Types` and `.Execute` modules respectively.
## Open questions:
1. `Hasura.RemoteSchema.Metadata.Types` is so called because I was hoping that all of the metadata related APIs of remote schema can be brought in at `Hasura.RemoteSchema.Metadata.API`. However, as metadata APIs depended on functions from `SchemaCache` module (see [1](ceba6d6226/server/src-lib/Hasura/RQL/DDL/RemoteSchema.hs (L55)) and [2](ceba6d6226/server/src-lib/Hasura/RQL/DDL/RemoteSchema.hs (L91)), it made more sense to create a separate top-level module for `MetadataAPI`s.
Maybe we can just have `Hasura.RemoteSchema.Metadata` and get rid of the extra nesting or have `Hasura.RemoteSchema.Metadata.{Core,Permission,RemoteRelationship}` if we want to break them down further.
1. `buildRemoteSchemas` in `H.RS.SchemaCache.Build` has the following type:
```haskell
buildRemoteSchemas ::
( ArrowChoice arr,
Inc.ArrowDistribute arr,
ArrowWriter (Seq CollectedInfo) arr,
Inc.ArrowCache m arr,
MonadIO m,
HasHttpManagerM m,
Inc.Cacheable remoteRelationshipDefinition,
ToJSON remoteRelationshipDefinition,
MonadError QErr m
) =>
Env.Environment ->
( (Inc.Dependency (HashMap RemoteSchemaName Inc.InvalidationKey), OrderedRoles),
[RemoteSchemaMetadataG remoteRelationshipDefinition]
)
`arr` HashMap RemoteSchemaName (PartiallyResolvedRemoteSchemaCtxG remoteRelationshipDefinition, MetadataObject)
```
Note the dependence on `CollectedInfo` which is defined as
```haskell
data CollectedInfo
= CIInconsistency InconsistentMetadata
| CIDependency
MetadataObject
-- ^ for error reporting on missing dependencies
SchemaObjId
SchemaDependency
deriving (Eq)
```
this pretty much means that remote schemas is dependent on types from databases, actions, ....
How do we fix this? Maybe introduce a typeclass such as `ArrowCollectRemoteSchemaDependencies` which is defined in `Hasura.RemoteSchema` and then implemented in graphql-engine?
1. The dependency on `buildSchemaCacheFor` in `.MetadataAPI.Execute` which has the following signature:
```haskell
buildSchemaCacheFor ::
(QErrM m, CacheRWM m, MetadataM m) =>
MetadataObjId ->
MetadataModifier ->
```
This can be easily resolved if we restrict what the metadata APIs are allowed to do. Currently, they operate in an unfettered access to modify SchemaCache (the `CacheRWM` constraint):
```haskell
runAddRemoteSchema ::
( QErrM m,
CacheRWM m,
MonadIO m,
HasHttpManagerM m,
MetadataM m,
Tracing.MonadTrace m
) =>
Env.Environment ->
AddRemoteSchemaQuery ->
m EncJSON
```
This should instead be changed to restrict remote schema APIs to only modify remote schema metadata (but has access to the remote schemas part of the schema cache), this dependency is completely removed.
```haskell
runAddRemoteSchema ::
( QErrM m,
MonadIO m,
HasHttpManagerM m,
MonadReader RemoteSchemasSchemaCache m,
MonadState RemoteSchemaMetadata m,
Tracing.MonadTrace m
) =>
Env.Environment ->
AddRemoteSchemaQuery ->
m RemoteSchemeMetadataObjId
```
The idea is that the core graphql-engine would call these functions and then call
`buildSchemaCacheFor`.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6291
GitOrigin-RevId: 51357148c6404afe70219afa71bd1d59bdf4ffc6
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
I didn't track why these were left behind. Presumably GHC 9.2 has an improved redundant constraint checker, so that explains a few. Otherwise, perhaps code got refactored along the way.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6256
GitOrigin-RevId: b6275edf3e867f8e33bdec533ce9932381d36bbb
### 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
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
### Description
I am not 100% sure about this PR; while I think the code is better this way, I'm willing to be convinced otherwise.
In short, this PR moves the `RoleName` field into the `SchemaContext`, instead of being a nebulous `Has RoleName` constraint on the reader monad. The major upside of this is that it makes it an explicit named field, rather than something that must be given as part of a tuple of arguments when calling `runReader`.
However, the downside is that it breaks the helper permissions functions of `Schema.Table`, which relied on `Has RoleName r`. This PR makes the choice of passing the role name explicitly to all of those functions, which in turn means first explicitly fetching the role name in a lot of places. It makes it more explicit when a schema building block relies on the role name, but is a bit verbose...
### Alternatives
Some alternatives worth considering:
- attempting something like `Has context r, Has RoleName context`, which would allow them to be independent from the context but still fetch the role name from the reader, but might require type annotations to not be ambiguous
- keeping the permission functions the same, with `Has RoleName r`, and introducing a bunch of newtypes instead of using tuples to explicitly implement all the required `Has` instances
- changing the permission functions to `Has SchemaContext r`, since they are functions used only to build the schema, and therefore may be allowed to be tied to the context.
What do y'all think?
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5073
GitOrigin-RevId: 8fd09fafb54905a4d115ef30842d35da0c3db5d2
In the process of decoupling the schema parsers from the GraphQL Engine, we need to remove dependencies on `Hasura.Base.Error`.
First of all, we have avoided using `QErr` in schema parsers code, instead returning a more appropriate data type which can be converted to a `Hasura.Base.Error.QErr` later.
Secondly, we create a new `ParseErrorCode` type to represent parse failure types, which are then converted to a `Hasura.Base.Error.Code` later.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5181
GitOrigin-RevId: 8655e26adb1e7d5e3d552c77a8a403f987b53467
