[T3 Connect] TypeScript codegen: type DbConnection.db with a merged interface for Babel/Expo

crates/codegen/src/typescript.rs

@@ -759,16 +759,23 @@ impl Lang for TypeScript {
         );
 
         writeln!(out);
+        if has_table_accessor_aliases {
+            // Narrow `db` by merging an interface into the class rather than with a
+            // `declare` field, which Babel (React Native, Expo) rejects by default.
+            writeln!(out, "export interface DbConnection {{");
+            out.indent(1);
+            writeln!(out, "db: DbView;");
+            out.dedent(1);
+            writeln!(out, "}}");
+            writeln!(out);
+        }
         writeln!(out, "/** The typed database connection to manage connections to the remote SpacetimeDB instance. This class has type information specific to the generated module. */");
         writeln!(
             out,
             "export class DbConnection extends __DbConnectionImpl<typeof REMOTE_MODULE> {{"
         );
         out.indent(1);
         if has_table_accessor_aliases {
-            writeln!(out, "declare db: DbView;");
-
-            writeln!(out);
             writeln!(
                 out,
                 "constructor(config: __DbConnectionConfig<typeof REMOTE_MODULE>) {{"

crates/codegen/tests/snapshots/codegen__codegen_typescript.snap

@@ -409,10 +409,12 @@ export class SubscriptionBuilder extends __SubscriptionBuilderImpl<typeof REMOTE
 /** Builder class to configure a new database connection to the remote SpacetimeDB instance. */
 export class DbConnectionBuilder extends __DbConnectionBuilder<DbConnection> {}
 
+export interface DbConnection {
+  db: DbView;
+}
+
 /** The typed database connection to manage connections to the remote SpacetimeDB instance. This class has type information specific to the generated module. */
 export class DbConnection extends __DbConnectionImpl<typeof REMOTE_MODULE> {
-  declare db: DbView;
-
   constructor(config: __DbConnectionConfig<typeof REMOTE_MODULE>) {
     super(config);
     this.db = __withTableAccessorAliases(this.db) as DbView;