https://github.com/ajermakovics/lambda2sql

Convert Java lambdas to SQL statements. Build type safe and readable queries.
https://github.com/ajermakovics/lambda2sql

java lambda orm sql

Last synced: about 2 months ago
JSON representation

Convert Java lambdas to SQL statements. Build type safe and readable queries.

• Host: GitHub
• URL: https://github.com/ajermakovics/lambda2sql
• Owner: ajermakovics
• License: mit
• Created: 2014-11-12T11:41:44.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2020-04-10T13:13:26.000Z (over 4 years ago)
• Last Synced: 2024-10-31T22:42:08.215Z (about 2 months ago)
• Topics: java, lambda, orm, sql
• Language: Java
• Homepage:
• Size: 24.4 KB
• Stars: 64
• Watchers: 10
• Forks: 10
• Open Issues: 1
• Metadata Files:
  • Readme: README.MD
  • License: LICENSE

Awesome Lists containing this project

README

        
Lambda2sql (lambda) -> "sql"

==========

[![](https://jitpack.io/v/ajermakovics/lambda2sql.svg)](https://jitpack.io/#ajermakovics/lambda2sql)

Convert Java 8 lambdas to SQL statements.

For example, the following Predicate:

```jshelllanguage

 person -> person.getAge() < 100 && person.getHeight() > 200

```

 

is converted to a string:

 

```

  age < 100 AND height > 200

```

allowing you to write readable queries in a type safe way.

See [Lambda2SqlTest](https://github.com/ajermakovics/lambda2sql/blob/master/src/test/java/lambda2sql/Lambda2SqlTest.java) for more examples or the [Wiki](https://github.com/ajermakovics/lambda2sql/wiki).

	

Usage

---------

```jshelllanguage

int age = 100;

int height = 200;

SqlPredicate predicate = person -> person.getAge() < age && person.getHeight() > height;

String sql = Lambda2Sql.toSql(predicate); // age < 100 AND height > 200

```

How it works

---------

It uses [JaQue](https://github.com/TrigerSoft/jaque) to build an expression tree for a lambda. The expression tree is then traversed and converted to a SQL statement. 

Under the hood, JaQue depends on the system property `jdk.internal.lambda.dumpProxyClasses`, if the lambda expression is not serialized:

See [https://bugs.openjdk.java.net/browse/JDK-8023524](https://bugs.openjdk.java.net/browse/JDK-8023524).

When the property is enabled, JVM generated classes for lambdas are saved to disk. JaQue then uses [ASM](http://asm.ow2.org/) to read the .class files and creates expression trees.

Since the interface [`SqlPredicate`](https://github.com/ajermakovics/lambda2sql/blob/master/src/main/java/lambda2sql/SqlPredicate.java) is automatically serialized, there is no need to set this property.

Limitations

---------

Current version only works with predicates and supports the following operators: >, >=, <, <=, =, !=, &&, ||, !

Install

-------

You can get the library using JitPack https://jitpack.io/#ajermakovics/lambda2sql/0.7

```gradle

repositories {

    maven { url "https://jitpack.io" }

}

dependencies {

    compile 'com.github.ajermakovics:lambda2sql:0.7'

}	

```

Build

---------

`gradle jar` or `gradle fatjar` to include dependencies.