Add fileCount GraphQL query for match counts without paging — Closes #77

README.md

@@ -148,7 +148,7 @@ The `cloudformation/backend.yml` `ImageURI` and `cloudformation/workers.yml` `Wo
 
 ### Queries
 
-The API exposes two queries: `files` (paginated list) and `file` (single lookup by MongoDB ObjectId).
+The API exposes queries including `files` (paginated list), `file` (single lookup by MongoDB ObjectId), and `fileCount` (match count for a filter).
 
 ```graphql
 query {
@@ -180,6 +180,8 @@ curl -X POST http://localhost:8000/metadata \
 
 Single file lookup: `{ file(id: "507f1f77bcf86cd799439011") { filename accessUrl } }`
 
+File count for a filter: `{ fileCount(input: [{ dcc: [{ dccAbbreviation: ["4DN"] }] }]) }` — returns the number of matching files without fetching any documents. It accepts the same `FileMetadataInput` filter shape as `files`; with no `input` it counts every file.
+
 ### Query Mechanics
 
 The GraphQL API uses an implicit OR/AND clause system for building MongoDB queries:

schema.graphql

@@ -506,6 +506,7 @@ type Query {
   files(input: [FileMetadataInput!] = null, page: Int! = 0, pageSize: Int! = 25): [FileMetadataType!]!
   file(id: ObjectIdScalar!): FileMetadataType
   distinctValues(fields: [String!]!, input: [FileMetadataInput!] = null): [DistinctFieldType!]!
+  fileCount(input: [FileMetadataInput!] = null): Int!
 }
 
 input SubjectInput {

src/cfdb/api/gql/schema.py

@@ -156,5 +156,19 @@ async def distinct_values(
             for field, values in zip(fields, all_values)
         ]
 
+    @strawberry.field
+    async def file_count(
+        self,
+        _: strawberry.Info,
+        input: list[FileMetadataInput] | None = None,
+    ) -> int:
+        # Wait for any database cutover to complete
+        await locks.wait_for_cutover()
+
+        assert api.db is not None
+        query = to_query(to_dict(input)) if input else {}
+
+        return await api.db.files.count_documents(query)
+
 
 schema = strawberry.Schema(query=Query)