refactor: return instance from Schema async constructor

PR-URL: #41

lib/schema-db.js

@@ -18,11 +18,15 @@ class DatabaseSchema {
   static async load(schemaPath) {
     const files = await fs.readdir(schemaPath, { withFileTypes: true });
     const dbPath = path.join(schemaPath, '.database.js');
-    const database = await new Schema(dbPath);
+    const dbSchema = await new Schema(dbPath);
+    if (!dbSchema) throw new Error(`File is not found: ${dbPath}`);
+    const { entity: database } = dbSchema;
     const typesPath = path.join(schemaPath, '.types.js');
-    const types = await new Schema(typesPath);
+    const typesSchema = await new Schema(typesPath);
+    if (!typesSchema) console.log(`File is not found: ${typesPath}`);
+    const { entity: types } = typesSchema || { entity: {} };
     const SchemaClass = DatabaseSchema.implementations[database.driver];
-    const dbSchema = new SchemaClass(schemaPath, database, types);
+    const databaseSchema = new SchemaClass(schemaPath, database, types);
     for (const file of files) {
       if (file.isDirectory()) continue;
       if (!file.name.endsWith('.js')) continue;
@@ -31,10 +35,10 @@ class DatabaseSchema {
       const schema = await new Schema(absPath);
       if (!schema) continue;
       const schemaName = path.basename(file.name, '.js');
-      dbSchema.entities.set(schemaName, schema);
+      databaseSchema.entities.set(schemaName, schema);
     }
-    await dbSchema.preprocess();
-    return dbSchema;
+    await databaseSchema.preprocess();
+    return databaseSchema;
   }
 
   async preprocess() {
@@ -54,7 +58,7 @@ class DatabaseSchema {
   }
 
   async reorderEntity(name) {
-    const entity = this.entities.get(name);
+    const { entity } = this.entities.get(name);
     const fields = Object.keys(entity);
     for (const field of fields) {
       const { type } = entity[field];
@@ -68,7 +72,7 @@ class DatabaseSchema {
   async validate() {
     console.log('Validating metaschema');
     for (const name of this.order) {
-      const entity = this.entities.get(name);
+      const { entity } = this.entities.get(name);
       const fields = Object.keys(entity);
       if (entity) console.log(`  ${name}: ${fields.length} fields`);
     }

lib/schema-pg.js

@@ -78,7 +78,7 @@ const primaryKey = entityName => {
 
 class PgSchema extends DatabaseSchema {
   async preprocessEntity(name) {
-    const entity = this.entities.get(name);
+    const { entity } = this.entities.get(name);
     const fields = Object.keys(entity);
     const types = { ...PG_TYPES, ...this.types };
     for (const fieldName of fields) {
@@ -102,7 +102,7 @@ class PgSchema extends DatabaseSchema {
   }
 
   async createEntity(name) {
-    const entity = this.entities.get(name);
+    const { entity } = this.entities.get(name);
     const sql = [];
     const idx = [];
     const types = { ...PG_TYPES, ...this.types };

lib/schema.js

@@ -17,11 +17,12 @@ class Schema {
       const src = await fs.readFile(this.path, 'utf8');
       if (!src) return null;
       const script = new vm.Script(src, { filename: this.path });
-      return script.runInThisContext(SCRIPT_OPTIONS);
+      this.entity = script.runInThisContext(SCRIPT_OPTIONS);
     } catch (err) {
       if (err.code !== 'ENOENT') {
         console.error(err.stack);
       }
+      return null;
     }
     return this;
   }