This is an example of a simple Entity DSL.

File entity.tx contains a grammar of the language. Each entity DSL model consists of zero or more simple types definitions and one or more Entity instances. Each Entity instance contains one or more Property instance. Each Property has a name conforming to built-in ID rule and a type which can be a reference to either SimpleType or Entity from the model or one of two built-in simple types representing basic types (integer and string, see file entity_test.py).

Example model is given in the file person.ent.

A program entity_test.py will instantiate meta-model from the grammar, register built-in simple types integer and string and register user class SimpleType so that built-in types can be instantiated from the code. A person example model is than parsed/instantiated by the meta-model and both meta-model and model are exported to .dot files in the folder dotexport.

An example of code generation is presented in the program entity_codegen.py. The code is generated in the srcgen subfolder using jinja2 template engine and the template java.template. For each Entity instance one java file is generated.

Note: Meta-model/grammar can be checked/visualized by textx command line tool but model can't because it depends on two built-in simple types (integer and string) which must be provided during meta-model instantiation (see entity_test.py file).

To run the example do the following:

• Verify that textX is installed. See documentation how to do that.

• Install Jinja2 for code generation

    $ pip install Jinja2
  

• From the Entity example folder run

    $ python entity_test.py
  

• Previous command will generate dot files in dotexport folder. To convert those files to PNG format do (you must have GraphViz installed):

    $ dot -Tpng -O dotexport/*.dot
  

  You will get entity_meta.dot.png (Entity meta-model) and person.dot.png (Person model) diagram.

• Run code generation:

    $ python entity_codegen.py
  

  This will produce html and js files to Address and Person in srcgen folder that corresponds to entities from the Person model.