feat: query to fetch unique columns

lib/discovery.js

@@ -301,6 +301,29 @@ function mixinDiscovery(MySQL, mysql) {
     return sql;
   };
 
+  /**
+   * Discover unique keys for a given table
+   * @param {String} table The table name
+   * @param {Object} options The options for discovery
+   */
+
+  /*!
+   * Retrieves a list of column names that have unique key index
+   * @param schema
+   * @param table
+   * @returns {string}
+   */
+  MySQL.prototype.buildQueryUniqueKeys = function(schema, table) {
+    const sql = 'SELECT Column_name AS "columnName",' +
+    ' table_schema AS "owner",' +
+    ' table_name AS "tableName"' +
+    ' FROM Information_schema.statistics' +
+    ' WHERE Table_schema = ' + mysql.escape(schema) +
+    ' AND Table_name = ' + mysql.escape(table) +
+    ' AND Non_unique = 0 AND Index_name <> \'PRIMARY\';';
+    return sql;
+  };
+
   /**
    * Discover foreign keys that reference to the primary key of this table
    * @param {String} table The table name

package.json

@@ -33,7 +33,7 @@
     "@commitlint/config-conventional": "^19.6.0",
     "eslint": "^8.57.1",
     "eslint-config-loopback": "^13.1.0",
-    "loopback-datasource-juggler": "^5.1.3",
+    "loopback-datasource-juggler": "^5.1.4",
     "mocha": "^11.1.0",
     "rc": "^1.2.8",
     "should": "^13.2.3",

test/mysql.discover.test.js

@@ -283,6 +283,21 @@ describe('Discover LDL schema from a table', function() {
   });
 });
 
+describe('Discover unique properties', function() {
+  let schema;
+  before(function(done) {
+    db.discoverSchema('CUSTOMER', {owner: 'STRONGLOOP'}, function(err, schema_) {
+      schema = schema_;
+      done(err);
+    });
+  });
+  it('should validate unique key for customer', function() {
+    assert.ok(/STRONGLOOP/i.test(schema.options.mysql.schema));
+    assert.strictEqual(schema.options.mysql.table, 'CUSTOMER');
+    assert.strictEqual(schema.properties.email.index.unique, true);
+  });
+});
+
 describe('Discover and handle enum', function() {
   let schema;
   before(function(done) {

test/schema.sql

@@ -39,7 +39,8 @@ CREATE TABLE `CUSTOMER` (
   PRIMARY KEY (`ID`)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
 /*!40101 SET character_set_client = @saved_cs_client */;
-
+ALTER TABLE `CUSTOMER`
+ADD COLUMN `email` VARCHAR(100) UNIQUE;
 --
 -- Dumping data for table `CUSTOMER`
 --