# Loulan

**Repository Path**: kzzhr/Loulan

## Basic Information

- **Project Name**: Loulan
- **Description**: Rocking with your database
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2018-06-08
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Loulan [![Build Status](https://travis-ci.org/Kretech/Loulan.svg?branch=master)](https://travis-ci.org/Kretech/Loulan)

[Laravel-Eloquent](https://laravel.com/docs/eloquent) for java



[TOC]

## Why ?

https://www.jianshu.com/p/f3bf0af7a1ea



## Overview

```java
//  作者叫 庆，标签为 java 的所有已发布文章
List<Post> posts = Post.query
  .with("author", "tags")				// 预加载，自动把数据组装到 post.author 对象 
  .has("author.name", "庆")				// 一对多嵌套查询
  .has("tags", query -> query.whereIn("name", "java"))	// 多对多嵌套查询（*暂未实现）
  .published()						// 封装好的业务查询（*暂未实现）
  .get();
```



相当于以下三条 SQL 的结果合并起来。当然，真的想合并到对应的属性里，你还得一堆java代码。现在有了 Loulan，只需要上面几行代码。

```sql
--	post
SELECT post.*
FROM post
WHERE status = 'published' AND post.author_id IN (
  SELECT id
  FROM user
  WHERE name = '庆'
) AND post.id IN (
  SELECT post_id
  FROM post_tag
  WHERE tag_id IN (
    SELECT id
    FROM tag
    WHERE `name` IN ("java")
  )
)

-- author
SELECT *
FROM author
WHERE id IN (post1.id, post2.id, ...);

-- tag
SELECT *
FROM tag
WHERE id IN (
  SELECT tag_id
  FROM tag
  WHERE post_id IN (post1.id, ...)
)
```



## Scope

### Plugins

#### Soft Delete

```java
@SoftDelete()
class Post extends Model { 
}
```



### Custom Query

```java
interface PostQuery extends Query<Post> {
  
  default PostQuery published(Query query) {
    return query.where("status", "published");
  }
  
}
```



## Hooks



## Eager Loading

```java
Post post = Post.query.with("author", "tags").first();
System.out.println(post.author.name);
```



## Scalable

```java
@Connection(name = "db0")
@Table(name = "post")
class Post extends Model {
  
  public String getTable() {
    return super.getTable() + getId() % 10;
  }

}
```

properties:

```properties
loulan.connection.default = "db0"

loulan.connections.db0.dsn = "jdbc:mysql://127.0.0.1:3306/test"
loulan.connections.db0.user = "user"

loulan.connections.db1.dsn = "jdbc:mysql://127.0.0.1:3306/test"
loulan.connections.db1.read.user = "reader"
loulan.connections.db1.write.user = "writer"
```