Add endpoint to list available dialects (#1393)

* Add endpoint to list available dialects

* Add support for GraphQL querying of dialects

Author: shangyian

datajunction-server/datajunction_server/api/engines.py

@@ -13,12 +13,27 @@
 from datajunction_server.internal.access.authentication.http import SecureAPIRouter
 from datajunction_server.internal.engines import get_engine
 from datajunction_server.models.engine import EngineInfo
+from datajunction_server.models.dialect import DialectRegistry, DialectInfo
 from datajunction_server.utils import get_session, get_settings
 
 settings = get_settings()
 router = SecureAPIRouter(tags=["engines"])
 
 
+@router.get("/dialects", response_model=list[DialectInfo])
+async def list_dialects():
+    """
+    Returns a list of registered SQL dialects and their associated transpilation plugin class names.
+    """
+    return [
+        DialectInfo(
+            name=dialect,
+            plugin_class=plugin.__name__,
+        )
+        for dialect, plugin in DialectRegistry._registry.items()
+    ]
+
+
 @router.get("/engines/", response_model=List[EngineInfo])
 async def list_engines(
     *,

datajunction-server/datajunction_server/api/graphql/main.py

@@ -7,18 +7,21 @@
 from fastapi import Depends
 from strawberry.fastapi import GraphQLRouter
 from strawberry.types import Info
-
 from datajunction_server.api.graphql.queries.catalogs import list_catalogs
 from datajunction_server.api.graphql.queries.dag import common_dimensions
-from datajunction_server.api.graphql.queries.engines import list_engines
+from datajunction_server.api.graphql.queries.engines import list_engines, list_dialects
 from datajunction_server.api.graphql.queries.nodes import (
     find_nodes,
     find_nodes_paginated,
 )
 from datajunction_server.api.graphql.queries.sql import measures_sql
 from datajunction_server.api.graphql.queries.tags import list_tag_types, list_tags
 from datajunction_server.api.graphql.scalars import Connection
-from datajunction_server.api.graphql.scalars.catalog_engine import Catalog, Engine
+from datajunction_server.api.graphql.scalars.catalog_engine import (
+    Catalog,
+    Engine,
+    DialectInfo,
+)
 from datajunction_server.api.graphql.scalars.node import DimensionAttribute, Node
 from datajunction_server.api.graphql.scalars.sql import GeneratedSQL
 from datajunction_server.api.graphql.scalars.tag import Tag
@@ -81,9 +84,15 @@ class Query:
     # Catalog and engine queries
     list_catalogs: list[Catalog] = strawberry.field(
         resolver=log_resolver(list_catalogs),
+        description="List available catalogs",
     )
     list_engines: list[Engine] = strawberry.field(
         resolver=log_resolver(list_engines),
+        description="List all available engines",
+    )
+    list_dialects: list[DialectInfo] = strawberry.field(
+        resolver=log_resolver(list_dialects),
+        description="List all supported SQL dialects",
     )
 
     # Node search queries
@@ -105,6 +114,7 @@ class Query:
     # Generate SQL queries
     measures_sql: list[GeneratedSQL] = strawberry.field(
         resolver=log_resolver(measures_sql),
+        description="Get measures SQL for a list of metrics, dimensions, and filters.",
     )
 
     # Tags queries

datajunction-server/datajunction_server/api/graphql/queries/engines.py

@@ -7,7 +7,8 @@
 from sqlalchemy import select
 from strawberry.types import Info
 
-from datajunction_server.api.graphql.scalars.catalog_engine import Engine
+from datajunction_server.models.dialect import DialectRegistry
+from datajunction_server.api.graphql.scalars.catalog_engine import Engine, DialectInfo
 from datajunction_server.database.engine import Engine as DBEngine
 
 
@@ -23,3 +24,19 @@ async def list_engines(
         Engine.from_pydantic(engine)  # type: ignore #pylint: disable=E1101
         for engine in (await session.execute(select(DBEngine))).scalars().all()
     ]
+
+
+async def list_dialects(
+    *,
+    info: Info = None,
+) -> List[DialectInfo]:
+    """
+    List all supported dialects
+    """
+    return [
+        DialectInfo(  # type: ignore
+            name=dialect,
+            plugin_class=plugin.__name__,
+        )
+        for dialect, plugin in DialectRegistry._registry.items()
+    ]

datajunction-server/datajunction_server/api/graphql/scalars/catalog_engine.py

@@ -4,7 +4,8 @@
 
 from datajunction_server.models.catalog import CatalogInfo
 from datajunction_server.models.engine import EngineInfo
-from datajunction_server.models.node import Dialect as Dialect_
+from datajunction_server.models.dialect import Dialect as Dialect_
+from datajunction_server.models.dialect import DialectInfo as DialectInfo_
 
 Dialect = strawberry.enum(Dialect_)
 
@@ -21,3 +22,10 @@ class Catalog:
     """
     Class for a Catalog
     """
+
+
+@strawberry.experimental.pydantic.type(model=DialectInfo_, all_fields=True)
+class DialectInfo:
+    """
+    Class for DialectInfo
+    """

datajunction-server/datajunction_server/api/graphql/schema.graphql

@@ -85,6 +85,11 @@ enum Dialect {
   DRUID
 }
 
+type DialectInfo {
+  name: String!
+  pluginClass: String!
+}
+
 type DimensionAttribute {
   name: String!
   attribute: String
@@ -331,9 +336,15 @@ enum PartitionType {
 }
 
 type Query {
+  """List available catalogs"""
   listCatalogs: [Catalog!]!
+
+  """List all available engines"""
   listEngines: [Engine!]!
 
+  """List all supported SQL dialects"""
+  listDialects: [DialectInfo!]!
+
   """Find nodes based on the search parameters."""
   findNodes(
     """A fragment of a node name to search for"""
@@ -383,6 +394,8 @@ type Query {
     """A list of nodes to find common dimensions for"""
     nodes: [String!] = null
   ): [DimensionAttribute!]!
+
+  """Get measures SQL for a list of metrics, dimensions, and filters."""
   measuresSql(
     cube: CubeDefinition!
     engine: EngineSettings = null

datajunction-server/datajunction_server/models/dialect.py

@@ -1,4 +1,6 @@
 import logging
+
+from pydantic import BaseModel
 from datajunction_server.enum import StrEnum
 from datajunction_server.utils import get_settings
 from typing import TYPE_CHECKING
@@ -42,6 +44,15 @@ def _missing_(cls, value: object) -> "Dialect":
         raise TypeError(f"{value!r} is not a valid string for {cls.__name__}")
 
 
+class DialectInfo(BaseModel):
+    """
+    Information about a SQL dialect and its associated plugin class.
+    """
+
+    name: str
+    plugin_class: str
+
+
 class DialectRegistry:
     """
     Registry for SQL dialect plugins.

datajunction-server/tests/api/engine_test.py

@@ -151,3 +151,28 @@ async def test_engine_raise_on_engine_already_exists(
     assert response.status_code == 409
     data = response.json()
     assert data == {"detail": "Engine already exists: `spark-three` version `3.3.1`"}
+
+
+@pytest.mark.asyncio
+async def test_dialects_list(
+    module__client: AsyncClient,
+) -> None:
+    """
+    Test listing dialects
+    """
+    response = await module__client.get("/dialects/")
+    assert response.status_code == 200
+    assert response.json() == [
+        {
+            "name": "spark",
+            "plugin_class": "SQLTranspilationPlugin",
+        },
+        {
+            "name": "druid",
+            "plugin_class": "SQLTranspilationPlugin",
+        },
+        {
+            "name": "trino",
+            "plugin_class": "SQLTranspilationPlugin",
+        },
+    ]

datajunction-server/tests/api/graphql/engine_test.py

@@ -62,3 +62,41 @@ async def test_engine_list(
             ],
         },
     }
+
+
+@pytest.mark.asyncio
+async def test_list_dialects(
+    client: AsyncClient,
+) -> None:
+    """
+    Test listing dialects
+    """
+    query = """
+    {
+        listDialects{
+            name
+            pluginClass
+        }
+    }
+    """
+    response = await client.post("/graphql", json={"query": query})
+    assert response.status_code == 200
+    data = response.json()
+    assert data == {
+        "data": {
+            "listDialects": [
+                {
+                    "name": "spark",
+                    "pluginClass": "SQLTranspilationPlugin",
+                },
+                {
+                    "name": "druid",
+                    "pluginClass": "SQLTranspilationPlugin",
+                },
+                {
+                    "name": "trino",
+                    "pluginClass": "SQLTranspilationPlugin",
+                },
+            ],
+        },
+    }