WIP - Add SetDefaultSchemaVersion

Will allow users to change their default database schema versions on demand, allowing rapid switching between (application) api/database versions.  It also allows them to define and apply schema updates eagerly, and then make the switch at a later date.

client/db.go

@@ -111,6 +111,15 @@ type Store interface {
 	// [FieldKindStringToEnumMapping].
 	PatchSchema(context.Context, string) error
 
+	// SetDefaultSchemaVersion sets the default schema version to the ID provided.  It will be applied to all
+	// collections using the schema.
+	//
+	// This will affect all operations interacting with the schema where a schema version is not explicitly
+	// provided.  This includes GQL queries and Collection operations.
+	//
+	// It will return an error if the provided schema version ID does not exist.
+	SetDefaultSchemaVersion(context.Context, string) error
+
 	// SetMigration sets the migration for the given source-destination schema version IDs. Is equivilent to
 	// calling `LensRegistry().SetMigration(ctx, cfg)`.
 	//

db/collection.go

@@ -300,7 +300,7 @@ func (db *db) updateCollection(
 		return nil, err
 	}
 
-	err = db.setDefaultSchemaVersion(ctx, txn, desc.Name, desc.Schema.SchemaID, schemaVersionID)
+	err = db.setDefaultSchemaVersionExplicit(ctx, txn, desc.Name, desc.Schema.SchemaID, schemaVersionID)
 	if err != nil {
 		return nil, err
 	}
@@ -585,6 +585,30 @@ func validateUpdateCollectionIndexes(
 }
 
 func (db *db) setDefaultSchemaVersion(
+	ctx context.Context,
+	txn datastore.Txn,
+	schemaVersionID string,
+) error {
+	col, err := db.getCollectionByVersionID(ctx, txn, schemaVersionID)
+	if err != nil {
+		return err
+	}
+
+	desc := col.Description()
+	err = db.setDefaultSchemaVersionExplicit(ctx, txn, desc.Name, desc.Schema.SchemaID, schemaVersionID)
+	if err != nil {
+		return err
+	}
+
+	cols, err := db.getCollectionDescriptions(ctx, txn)
+	if err != nil {
+		return err
+	}
+
+	return db.parser.SetSchema(ctx, txn, cols)
+}
+
+func (db *db) setDefaultSchemaVersionExplicit(
 	ctx context.Context,
 	txn datastore.Txn,
 	collectionName string,

db/txn_db.go

@@ -280,6 +280,25 @@ func (db *explicitTxnDB) PatchSchema(ctx context.Context, patchString string) er
 	return db.patchSchema(ctx, db.txn, patchString)
 }
 
+func (db *implicitTxnDB) SetDefaultSchemaVersion(ctx context.Context, schemaVersionID string) error {
+	txn, err := db.NewTxn(ctx, false)
+	if err != nil {
+		return err
+	}
+	defer txn.Discard(ctx)
+
+	err = db.setDefaultSchemaVersion(ctx, txn, schemaVersionID)
+	if err != nil {
+		return err
+	}
+
+	return txn.Commit(ctx)
+}
+
+func (db *explicitTxnDB) SetDefaultSchemaVersion(ctx context.Context, schemaVersionID string) error {
+	return db.setDefaultSchemaVersion(ctx, db.txn, schemaVersionID)
+}
+
 func (db *implicitTxnDB) SetMigration(ctx context.Context, cfg client.LensConfig) error {
 	txn, err := db.NewTxn(ctx, false)
 	if err != nil {

http/client.go

@@ -223,6 +223,17 @@ func (c *Client) PatchSchema(ctx context.Context, patch string) error {
 	return err
 }
 
+func (c *Client) SetDefaultSchemaVersion(ctx context.Context, schemaVersionID string) error {
+	methodURL := c.http.baseURL.JoinPath("schema", "default")
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, methodURL.String(), strings.NewReader(schemaVersionID))
+	if err != nil {
+		return err
+	}
+	_, err = c.http.request(req)
+	return err
+}
+
 func (c *Client) SetMigration(ctx context.Context, config client.LensConfig) error {
 	return c.LensRegistry().SetMigration(ctx, config)
 }

http/handler_store.go

@@ -164,6 +164,22 @@ func (s *storeHandler) PatchSchema(rw http.ResponseWriter, req *http.Request) {
 	rw.WriteHeader(http.StatusOK)
 }
 
+func (s *storeHandler) SetDefaultSchemaVersion(rw http.ResponseWriter, req *http.Request) {
+	store := req.Context().Value(storeContextKey).(client.Store)
+
+	schemaVersionID, err := io.ReadAll(req.Body)
+	if err != nil {
+		responseJSON(rw, http.StatusBadRequest, errorResponse{err})
+		return
+	}
+	err = store.SetDefaultSchemaVersion(req.Context(), string(schemaVersionID))
+	if err != nil {
+		responseJSON(rw, http.StatusBadRequest, errorResponse{err})
+		return
+	}
+	rw.WriteHeader(http.StatusOK)
+}
+
 func (s *storeHandler) GetCollection(rw http.ResponseWriter, req *http.Request) {
 	store := req.Context().Value(storeContextKey).(client.Store)
 

http/server.go

@@ -53,6 +53,7 @@ func NewServer(db client.DB) *Server {
 		api.Route("/schema", func(schema chi.Router) {
 			schema.Post("/", store_handler.AddSchema)
 			schema.Patch("/", store_handler.PatchSchema)
+			schema.Post("/default", store_handler.SetDefaultSchemaVersion)
 		})
 		api.Route("/collections", func(collections chi.Router) {
 			collections.Get("/", store_handler.GetCollection)

http/wrapper.go

@@ -90,6 +90,10 @@ func (w *Wrapper) PatchSchema(ctx context.Context, patch string) error {
 	return w.client.PatchSchema(ctx, patch)
 }
 
+func (w *Wrapper) SetDefaultSchemaVersion(ctx context.Context, schemaVersionID string) error {
+	return w.client.SetDefaultSchemaVersion(ctx, schemaVersionID)
+}
+
 func (w *Wrapper) SetMigration(ctx context.Context, config client.LensConfig) error {
 	return w.client.SetMigration(ctx, config)
 }