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https://github.com/elastic-coders/py-graphqlparser

Python binding for libgraphqlparser
https://github.com/elastic-coders/py-graphqlparser

Last synced: 3 months ago
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Python binding for libgraphqlparser

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README 

        
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/