Web documentation for unique Dart columns

docs/lib/snippets/tables/advanced.dart

@@ -0,0 +1,17 @@
+import 'package:drift/drift.dart';
+
+// #docregion unique
+class WithUniqueConstraints extends Table {
+  IntColumn get a => integer().unique()();
+
+  IntColumn get b => integer()();
+  IntColumn get c => integer()();
+
+  @override
+  List<Set<Column>> get uniqueKeys => [
+        {b, c}
+      ];
+
+  // Effectively, this table has two unique key sets: (a) and (b, c).
+}
+// #enddocregion unique

docs/pages/docs/Getting started/advanced_dart_tables.md

@@ -1,7 +1,7 @@
 ---
 data:
   title: "Dart tables"
-  description: Further information on Dart tables
+  description: Further information on defining tables in Dart.
   weight: 150
 template: layouts/docs/single
 ---
@@ -11,6 +11,8 @@ __Prefer sql?__ If you prefer, you can also declare tables via `CREATE TABLE` st
 Drift's sql analyzer will generate matching Dart code. [Details]({{ "starting_with_sql.md" | pageUrl }}).
 {% endblock %}
 
+{% assign snippets = 'package:moor_documentation/snippets/tables/advanced.dart.excerpt.json' | readString | json_decode %}
+
 As shown in the [getting started guide]({{ "index.md" | pageUrl }}), sql tables can be written in Dart:
 ```dart
 class Todos extends Table {
@@ -128,6 +130,19 @@ Note that the primary key must essentially be constant so that the generator can
 - it must be defined with the `=>` syntax, function bodies aren't supported
 - it must return a set literal without collection elements like `if`, `for` or spread operators
 
+## Unique Constraints
+
+Starting from version 1.6.0, `UNIQUE` SQL constraints can be defined on Dart tables too.
+A unique constraint contains one or more columns. The combination of all columns in a constraint
+must be unique in the table, or the databas will report an error on inserts.
+
+With drift, a unique constraint can be added to a single column by marking it as `.unique()` in
+the column builder.
+A unique set spanning multiple columns can be added by overriding the `uniqueKeys` getter in the
+`Table` class:
+
+{% include "blocks/snippet" snippets = snippets name = 'unique' %}
+
 ## Supported column types
 
 Drift supports a variety of column types out of the box. You can store custom classes in columns by using