Update documentation

README.md

@@ -1,7 +1,13 @@
 # Micoli\Elql
 
 
-A flat database manager.
+A flat database manager. Each models are read/persisted in a (`YAML`|`JSON`) file.
+
+That library is based upon [`symfony/serializer`](https://symfony.com/doc/current/components/serializer.html) and [`symfony/expression-language`](https://symfony.com/doc/current/components/expression_language.html) components. So basically, every model that can be serialized/deserialized by those components wan be used.
+
+When `select`ing, `updat`ing, `delet`ing records, each constraints are expressed as an `expression-language` string.
+A `record` object is available in the constraint expression and represent the evaluated record. 
+
 
 [![Build Status](https://github.com/micoli/elql/workflows/Tests/badge.svg)](https://github.com/micoli/elql/actions)
 [![Coverage Status](https://coveralls.io/repos/github/micoli/Elql/badge.svg?branch=main)](https://coveralls.io/github/micoli/Elql?branch=main)
@@ -26,5 +32,130 @@ This library requires PHP 8.0 or later.
 
 While this library is still under development, it is still in early development status. It follows semver version tagging.
 
-[//]: # (## Quick start)
+## Quick start
+
+### Create an instance of Elql manager
+
+Database are per directory. all models are persisted in a separate file.
+
+```php
+$database = new Elql(
+    new FilePersister(
+        '/var/lib/database',
+        new MetadataManager(),
+        YamlEncoder::FORMAT,
+    ),
+);
+```
+
+### Record in memory addition
+
+```php
+// add some record of proper serializable model
+$database->add(
+    new Baz(1, 'a', 'a'),
+    new Baz(2, 'b', 'b'),
+    new Baz(3, 'c', 'c'),
+    new Baz(4, 'd', 'd'),
+    new Foo(1, 'aa', new DateTimeImmutable()),
+);
+```
+
+### Basic crud function are available
+
+#### Select
 
+```php
+$records = $database->find(Baz::class, 'record.id==3');
+````
+
+#### Update
+
+An updater callback is used to help case/case model updates
+
+```php
+$database->update(Baz::class, function (Baz $record) {
+    $record->firstName = $record->firstName . '-updated';
+
+    return $record;
+}, 'record.id==3');
+```
+
+#### Delete
+
+```php
+$database->delete(Baz::class, 'record.id in [1,4]');
+```
+
+#### Count
+
+```php
+print $database->count(Baz::class, 'record.id in [1,4]');
+```
+
+#### You need to flush the in-memories tables to disk to persist them
+
+```php
+$database->persister->flush();
+```
+
+
+```
+/var/lib/database/Foo.yaml
+/var/lib/database/Bar.yaml
+```
+
+
+## Attributes
+
+### Table($name)
+
+Instead of using the class-name as filename, you can specify a specific name using that attribute
+
+```php
+#[Table('b_a_z')]
+class Baz
+{
+    public function __construct(
+        public readonly int $id,
+        public string $firstName,
+        public string $lastName,
+    ) {
+    }
+}
+```
+N.B.:
+
+if you don't want to use that attribute, you can specify some filenames in the `MetadataManager` constructor:
+
+```php
+$database = new Elql(
+    new FilePersister(
+        '/var/lib/database',
+        new MetadataManager([
+            Foo::class=>'foo_table'
+        ]),
+        YamlEncoder::FORMAT,
+    ),
+);
+```
+
+In that was, when `Foo` records will be persisted, the filename will be `foo_table.yaml`
+
+### Unique($expression, $indexName)
+
+Before adding a record to a model table, the unique constraints are evaluated to guarantee uniqueness of records
+
+```php
+#[Unique('record.id')]
+#[Unique('[record.firstName,record.lastName]', 'fullname')]
+class Baz
+{
+    public function __construct(
+        public readonly int $id,
+        public string $firstName,
+        public string $lastName,
+    ) {
+    }
+}
+```