Beaver

Beaver is a code generation tool which can accept an input structure (json, yaml, ini, or xml) along with a template file, and produces code by combining the two.

It uses Jinja2 for templating.

Installing

pip install -e git+https://github.com/clagraff/beaver.git#egg=beaver

tl;dr

$ beaver one template.tpl data.json                                     # generate code and print to STDOUT
$ beaver one template.tpl stuff.yaml -o my_code.cpp                     # generate code and write to file
$ beaver one template.tpl config.ini --post indent -st -o indented.c    # generate code, indent the code, write to file

$ beaver many template.tpl {{__name__}}.cpp *.json                      # generate code from JSON files, write to .cpp files
$ beaver many templates.tpl foo{{__index__}}.c *.yaml --post indent -st # generate code from yaml files, write to .cpp files after indenting.

Generate Code

Data Formats

Beaver supports the following input formats for data:

JSON
Yaml
XML
INI

... with plans to include some additional format types.

Templating

Beaver uses Jinja2 for templating. This means you can leaverage Jinja filters and functions, along with all the other niceties that come with using Jinja.

Never used Jinja2 before? You can learn how to get started or jump specifically to their template documention

Generate one file

To generate one specific file, you can use the one sub-command. You must specify a Jinja2 template of the code structure, and the input data (JSON, Yaml, XML, or INI) file.

The command will output to STDOUT by default, unless the -o flag is used to specify an output file.

$ beaver one template.tpl input.json -o output.code

Generate multiple files

To generate multiple files at once, you can use the many sub-command.

$ beaver one template.tpl one_output_file.java input_1.json input_2.xml input_3.yaml
$ beaver one template.tpl one_output_file.java *.{json,xml,yaml}

Real-world example

Let's pretend we want to a Golang struct based on a Yaml file. Here are the two files:

struct.tpl

// {{ name }} is a test struct
type {{ name }} struct {
{% for key in attributes -%}
    {%- set attr = attributes[key] -%}
    {{ key }}   {{ attr.type }}{% if attr.json %} `json:"{{ attr.json }}"`{% endif %}
{% endfor -%}
}

// Print will print out the contents of {{ name }}
func ({{ name[0] }} {{ name }}) Print() {
    fmt.Println("{{ name }}: ")
{% for key in attributes -%}
    fmt.Println("{{ key }} -", {{ name[0] }}.{{ key }})
{% endfor -%}
}

data.yaml

name: MyAwesomeStruct
attributes:
    ID:
        type: "*int64"
        json: id
    Data:
        type: float64
        json: "-"
    Secret:
        type: string
    DBConn:
        type: sql.DB
        json: conn

To generate code, we can run:

$ beaver one struct.tpl data.yaml -o struct.go
$ cat struct.go
// MyAwesomeStruct is a test struct
type MyAwesomeStruct struct {
ID   *int64 `json:"id"`
Data   float64 `json:"-"`
Secret   string
DBConn   sql.DB `json:"conn"`
}

// Print will print out the contents of MyAwesomeStruct
func (M MyAwesomeStruct) Print() {
    fmt.Println("MyAwesomeStruct: ")
fmt.Println("ID -", M.ID)
fmt.Println("Data -", M.Data)
fmt.Println("Secret -", M.Secret)
fmt.Println("DBConn -", M.DBConn)
}

Hmm. Unfortunately that code is not quite formatted right. But no worries!

We can use some post-rendering commands to fix it. These commands will execute against the code after it is rendered, but before it is outputted.

$ beaver one struct.tpl data.yaml --post gofmt --post goimports -o struct.go
$ cat struct.go
import (
	"database/sql"
	"fmt"
)

// MyAwesomeStruct is a test struct
type MyAwesomeStruct struct {
	ID     *int64  `json:"id"`
	Data   float64 `json:"-"`
	Secret string
	DBConn sql.DB `json:"conn"`
}

// Print will print out the contents of MyAwesomeStruct
func (M MyAwesomeStruct) Print() {
	fmt.Println("MyAwesomeStruct: ")
	fmt.Println("ID -", M.ID)
	fmt.Println("Data -", M.Data)
	fmt.Println("Secret -", M.Secret)
	fmt.Println("DBConn -", M.DBConn)
}

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

Authors

Curtis La Graff - Author - Profile

License

This project is licensed under the MIT License - see the LICENSE.md file for details

clagraff / beaver