## Description
This is the first step in making use of Logical Models with document databases such as MongoDB. As part of schema introspection, a data connector agent can supply a set of custom types that can be used to describe the schema for columns within the tables of the database (or _fields_ within a _document collection_ in MongoDB terminology).
Previously, we were storing these custom types as `TableObjectType`s within the `TableCoreInfo` for each table.
In this PR we
- replace the `TableObjectTypes` with `LogicalModel` types
- store these directly within the `DBObjectsIntrospection` instead of within the `TableCoreInfo` for each table. (The custom types are shared at the source level so there was no reason to have a separate set of types for each table.)
- When building the `SourceInfo`, we combine the `LogicalModel`s from `DBObjectsIntrospection` with `LogicalModel`s from the user's metadata to create the set of `LogicalModels` in the `SourceInfo` within the `SchemaCache`. I.e. we combine the set of types obtained by database introspection with the set of types specified by the user in the metadata. If two types have the same name, we use the type defined in the metadata.
## Limitations and future work
- Provide a way for the user to associate a meta-data defined `LogicalModel` with a table instead of requiring one to be provided by DB introspection
- Provide a way for the user to edit the `LogicalModel` types provided by introspection and add them to the metadata.
- Allow a `LogicalModel` object type to describe and entire table rather than just individual columns.
- Better handling for "unknown" types, e.g. if the type of a collection (or part of a collection) is unknown we should treat it as a JSON scalar value. This may also involve adding an `_everything` field which returns the full document as a JSON scalar.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9345
GitOrigin-RevId: 5cec72fc1be1380d8600f7be547bbf71aad770bd
## 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
## 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
Also add a `default` implementation for `MonadQueryTags`.
This avoids a bunch of imports on `Hasura.GraphQL.Execute.Backend` which is a big module with lots of (transitive) dependencies.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/8571
GitOrigin-RevId: 8ecca452721b77953e6d088c79d8d6f003f2996f
This PR implements the remaining codecs for table permissions. However the codec for boolean expressions delegates to Aeson instances because Autodocodec doesn't currently have the necessary feature to write a codec for boolean expressions that will reliably parse valid data.
Boolean expressions are objects with keys like `_and`, `_or`, `_exists`, or `<field name>`. The parsing rules for each value depend on the key, so we need to be able to select different codecs for each key. We could do that with an `object` codec, but that doesn't account for the arbitrary field name keys that can be provided. OpenAPI supports object types with "additional properties", but I don't know if we can declare a specific type for those properties. There might or might not be a reasonable path to extending Autodocodec to handle this case.
Ticket: [GDC-585](https://hasurahq.atlassian.net/browse/GDC-585)
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6978
GitOrigin-RevId: 0b0dcfd59ebd1d5022ff2ab86dd8d4c6f93bd039
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
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
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
