Foreign keys for pg SQL DDL

lib/ddl.js

@@ -1,10 +1,7 @@
 'use strict';
 
 const { DatabaseSchema } = require('./schema-db.js');
-
-const toLowerCamel = s => s.charAt(0).toLowerCase() + s.slice(1);
-const toUpperCamel = s => s.charAt(0).toUpperCase() + s.slice(1);
-const isUpperCamel = s => s[0] === s[0].toUpperCase();
+const { toLowerCamel, toUpperCamel, isUpperCamel } = require('./utils.js');
 
 const DB_RELATION = 1;
 const DB_FIELD = 2;
@@ -45,6 +42,21 @@ const createIndex = (entityName, { name, unique, index }) => {
   return `CREATE ${uni}INDEX ${idxName} ON ${idxOn};`;
 };
 
+const foreignKey = (entityName, { name, type }) => {
+  const fk = 'fk' + entityName + toUpperCamel(name);
+  return (
+    `ALTER TABLE "${entityName}" ADD CONSTRAINT "${fk}" ` +
+    `FOREIGN KEY ("${name}") ` +
+    `REFERENCES "${type}" ("${type}Id") ON DELETE CASCADE;`
+  );
+};
+
+const primaryKey = entityName => {
+  const fieldName = toLowerCamel(entityName) + 'Id';
+  const constraint = `"pk${entityName}" PRIMARY KEY ("${fieldName}")`;
+  return `ALTER TABLE "${entityName}" ADD CONSTRAINT ${constraint};`;
+};
+
 class PgSchema extends DatabaseSchema {
   async preprocessEntity(name, entity) {
     const fields = Object.keys(entity);
@@ -63,8 +75,7 @@ class PgSchema extends DatabaseSchema {
     sql.push(`CREATE TABLE "${name}" (`);
     const pk = toLowerCamel(name) + 'Id';
     sql.push(`  "${pk}" bigint unsigned generated always as identity,`);
-    const constraint = `"pk${name}" PRIMARY KEY ("${pk}")`;
-    idx.push(`ALTER TABLE "${name}" ADD CONSTRAINT ${constraint};`);
+    idx.push(primaryKey(name));
     const fields = Object.keys(entity);
     for (const fieldName of fields) {
       const def = entity[fieldName];
@@ -75,6 +86,7 @@ class PgSchema extends DatabaseSchema {
         if (!pgType) throw new Error(`Unknown type: ${def.type}`);
         const pgField = def.name + (kind === DB_FIELD ? '' : 'Id');
         sql.push(`  "${pgField}" ${pgType}${nullable},`);
+        if (kind === DB_RELATION) idx.push(foreignKey(name, def));
       }
       if (def.unique || def.index) idx.push(createIndex(name, def));
     }

lib/schema-db.js

@@ -3,12 +3,14 @@
 const path = require('path');
 const fs = require('fs').promises;
 
+const { isUpperCamel } = require('./utils.js');
 const { Schema } = require('./schema.js');
 
 class DatabaseSchema {
   constructor(schemaPath) {
     this.path = schemaPath;
     this.entities = new Map();
+    this.order = new Set();
     return this.load();
   }
 
@@ -30,6 +32,11 @@ class DatabaseSchema {
     for (const [name, entity] of this.entities) {
       await this.preprocessEntity(name, entity);
     }
+    for (const [name, entity] of this.entities) {
+      if (!this.order.has(name)) {
+        await this.reorderEntity(name, entity);
+      }
+    }
   }
 
   async preprocessEntity(name, entity) {
@@ -38,9 +45,21 @@ class DatabaseSchema {
     throw new Error(`Method is not implemented: preprocessEntity(${args})`);
   }
 
+  async reorderEntity(name, entity) {
+    const fields = Object.keys(entity);
+    for (const field of fields) {
+      const { type } = entity[field];
+      if (isUpperCamel(type) && !this.order.has(type)) {
+        await this.reorderEntity(type, this.entities.get(type));
+      }
+    }
+    this.order.add(name);
+  }
+
   async validate() {
     console.log('Validating metaschema');
-    for (const [name, entity] of this.entities) {
+    for (const name of this.order) {
+      const entity = this.entities.get(name);
       const fields = Object.keys(entity);
       if (entity) console.log(`  ${name}: ${fields.length} fields`);
     }
@@ -49,7 +68,8 @@ class DatabaseSchema {
   async generate(outputPath) {
     console.log('Generating SQL DDL script ' + outputPath);
     const script = [];
-    for (const [name, entity] of this.entities) {
+    for (const name of this.order) {
+      const entity = this.entities.get(name);
       const sql = await this.generateEntity(name, entity);
       script.push(sql);
     }

lib/utils.js

@@ -30,9 +30,16 @@ const joinIterable = (val, sep) => {
   return res;
 };
 
+const toLowerCamel = s => s.charAt(0).toLowerCase() + s.slice(1);
+const toUpperCamel = s => s.charAt(0).toUpperCase() + s.slice(1);
+const isUpperCamel = s => !!s && s[0] === s[0].toUpperCase();
+
 module.exports = {
   escapeIdentifier,
   escapeKey,
   mapJoinIterable,
   joinIterable,
+  toLowerCamel,
+  toUpperCamel,
+  isUpperCamel,
 };

test/schema/Country.js

@@ -1,3 +1,4 @@
 ({
+  planet: 'Planet',
   name: { type: 'string', unique: true },
 });

test/schema/District.js

@@ -0,0 +1,4 @@
+({
+  city: 'City',
+  name: { type: 'string', unique: true },
+});

test/schema/Planet.js

@@ -0,0 +1,3 @@
+({
+  name: { type: 'string', unique: true },
+});