Graphql parser based on libgraphqlparser

.. image:: https://circleci.com/gh/elastic-coders/py-graphqlparser.svg?style=svg :target: https://circleci.com/gh/elastic-coders/py-graphqlparser

Python2.7+ Python3.4+ class-based bindings to libgraphqlparser; just a thin layer on top of libgraphqlparser C API.

Still EXPERIMENTAL

Installing

First install libgraphqlparser following instructions on libgraphqlparser github page_ .

Next you can install graphqlparser. The easiest way is using precompiled wheels which are usually available on graphqlparser github releases_

Pick the right wheel for your platform and python version, then install it using pip::

pip install https://github.com/elastic-coders/py-graphqlparser/releases/download/v0.0.4/graphqlparser-0.0.4-cp36-cp36m-linux_x86_64.whl

As an alternative you can install graphqlparser from source distribution:

• Install cython

• Set an env var $GRAPHQL_HOME to the folder where libgraphqlparser.so and Ast.h are

• Install graphqlparser with pip::

  LDFLAGS="-L$GRAPHQL_HOME" CFLAGS="-I$GRAPHQL_HOME/c -I$GRAPHQL_HOME" pip install graphqlparser

Usage

Make sure libgraphqlparser is available to the loader. You can add its base dir to LD_LIBRARY_PATH.

Then you can start parsing by creating your custom visitor class:

.. code-block:: python

from graphql_parser import GraphQLAstVisitor

class MyVisitor(GraphQLAstVisitor.GraphQLAstVisitor):

  def visit_field(self, node):
      print('start field %s visit' % node)
      # Return 1 to keep visiting children, 0 to skip them
      return 1

  def end_visit_field(self, node):
      print('end field %s visit' % node)

And using it to visit a parsed query:

.. code-block:: python

from graphql_parser import GraphQLParser

query = '{query{}}' node = GraphQLParser.graphql_parse_string(query) MyVisitor().visit_node(node)

See also examples folder.

Building from source checkout

Rebuild the generated cython files from the libgraphql AST (usually not needed)

• download submodules with git checkout --recursive

• build libgraphql library in folder ./libgraphqlparser (python2.7 required for building) (usually pushd libgraphqlparser && cmake . && make && popd works)

• generate source code with python ast/build_ast.py

• you can now switch to python 3

• install cython

• run::

  LDFLAGS="-L./libgraphqlparser" CFLAGS="-Ilibgraphqlparser/c -Ilibgraphqlparser" python setup.py build_ext

To create a wheel distribution:

• install wheel: pip install wheel
• create wheelhouse mkdir .wheelhouse
• build with pip wheel --wheel-dir=.wheelhouse .

Known issues

• Only (lightly) tested on python3
• Unicode string handling not yet complete (a mixture of bytes and strings all over)
• Exceptions in the visitor's class callbacks are ignored
• libgraphqlparser is dynamically linked but It would be better if it was linked statically

TODO

• build more wheel packages for linux 32 bit and other platforms

.. _libgraphqlparser github page: https://github.com/graphql/libgraphqlparser .. _graphqlparser github releases: https://github.com/elastic-coders/py-graphqlparser/releases/