feat: sequelize.random() (#8847)

Author: mccabemj

docs/querying.md

@@ -429,6 +429,9 @@ Subtask.findAll({
 
   // Will order by age ascending assuming ascending is the default order when direction is omitted
   order: sequelize.col('age')
+
+  // Will order by age randomly based on the dialect (instead of fn('RAND') or fn('RANDOM'))
+  order: sequelize.random()
 })
 ```
 

lib/sequelize.js

@@ -772,6 +772,20 @@ class Sequelize {
   databaseVersion(options) {
     return this.getQueryInterface().databaseVersion(options);
   }
+  
+  /**
+   * Get the fn for random based on the dialect
+   *
+   * @return {Sequelize.fn}
+   */
+  random() {
+    const dialect = this.getDialect();
+    if (_.includes(['postgres', 'sqlite'], dialect)) {
+      return this.fn('RANDOM');
+    } else {
+      return this.fn('RAND');
+    }
+  }
 
   /**
    * Creates an object representing a database function. This can be used in search queries, both in where and order parts, and as default values in column definitions.

test/unit/sql/order.test.js

@@ -344,6 +344,19 @@ describe(Support.getTestDialectTeaser('SQL'), () => {
       postgres: 'SELECT "Subtask"."id", "Subtask"."name", "Subtask"."createdAt", "Task"."id" AS "Task.id", "Task"."name" AS "Task.name", "Task"."created_at" AS "Task.createdAt", "Task->Project"."id" AS "Task.Project.id", "Task->Project"."name" AS "Task.Project.name", "Task->Project"."created_at" AS "Task.Project.createdAt" FROM "subtask" AS "Subtask" INNER JOIN "task" AS "Task" ON "Subtask"."task_id" = "Task"."id" INNER JOIN "project" AS "Task->Project" ON "Task"."project_id" = "Task->Project"."id" ORDER BY "Task->Project"."created_at" ASC, "Task->Project"."created_at", "Task"."created_at" ASC, "Task"."created_at", "Task->Project"."created_at" ASC, "Task->Project"."created_at", "Task"."created_at" ASC, "Task"."created_at", "Task->Project"."created_at" ASC, "Task->Project"."created_at", "Task"."created_at" ASC, "Task"."created_at", "Task->Project"."created_at" ASC, "Task->Project"."created_at", "Task"."created_at" ASC, "Task"."created_at", "Subtask"."created_at" ASC, "Subtask"."created_at", "Subtask"."created_at";'
     });
 
+    testsql({
+      model: Subtask,
+      attributes: ['id', 'name'],
+      order: [
+        Support.sequelize.random()
+      ]
+    }, {
+      mssql: 'SELECT [id], [name] FROM [subtask] AS [Subtask] ORDER BY RAND();',
+      mysql: 'SELECT `id`, `name` FROM `subtask` AS `Subtask` ORDER BY RAND();',
+      postgres: 'SELECT "id", "name" FROM "subtask" AS "Subtask" ORDER BY RANDOM();',
+      sqlite: 'SELECT `id`, `name` FROM `subtask` AS `Subtask` ORDER BY RANDOM();'
+    });
+  
     describe('Invalid', () => {
       it('Error on invalid association', () => {
         return expect(Subtask.findAll({