arxiv_metadata/routes/post.py

"""
This file contains POST routes methods.
"""
import bottle
import json
from sqlalchemy.exc import IntegrityError

import database
import tools
from reference_fetcher import arxiv


def create_paper(db):
    """
    Create a new resource identified by its DOI or arXiv eprint id.

    .. code-block:: bash

        POST /papers
        Content-Type: application/vnd.api+json
        Accept: application/vnd.api+json

        {
            "data": {
                "doi": "10.1126/science.1252319",
                // OR
                "arxiv_id": "1401.2910"
            }
        }


    .. code-block:: json

        {
            "data": {
                {
                    "type": "papers",
                    "id": 1,
                    "attributes": {
                        "doi": "10.1126/science.1252319",
                        "arxiv_id": "1401.2910"
                    },
                    "links": {
                        "self": "/papers/1"
                    },
                    "relationships": {
                        TODO
                    }
                }
            }
        }

    :param db: A database session, injected by the ``Bottle`` plugin.
    :returns: An ``HTTPResponse``.
    """
    data = json.loads(bottle.request.body.read().decode("utf-8"))
    # Validate the request
    if("data" not in data or
       "type" not in data["data"] or
       data["data"]["type"] != "papers" or
       ("doi" not in data["data"] and "arxiv_id" not in data["data"])):
        return bottle.HTTPError(403, "Forbidden")

    data = data["data"]

    if "doi" in data:
        paper = create_by_doi(data["doi"], db)
    elif "arxiv_id" in data:
        paper = create_by_arxiv(data["arxiv"], db)

    if paper is None:
        return bottle.HTTPError(409, "Conflict")

    # Return the resource
    response = {
        "data": paper.json_api_repr()
    }
    # TODO: Return a 202 as the resource has been accepted but is not yet
    # processed, especially since its relationships have not yet been fetched.
    headers = {"Location": "/papers/%d" % (paper.id,)}
    return tools.APIResponse(status=202,
                             body=tools.pretty_json(response),
                             headers=headers)


def create_by_doi(doi, db):
    """
    Create a new resource identified by its DOI, if it does not exist.

    :param doi: The DOI of the paper.
    :param db: A database session.
    :returns: ``None`` if insertion failed, the ``Paper`` object otherwise.
    """
    paper = database.Paper(doi=doi)

    # Try to fetch an arXiv id
    arxiv_id = arxiv.get_arxiv_eprint_from_doi(doi)
    if arxiv_id:
        paper.arxiv_id = arxiv_id

    # Add it to the database
    try:
        db.add(paper)
        db.flush()
    except IntegrityError:
        # Unique constraint violation, paper already exists
        db.rollback()
        return None

    # Return the paper
    return paper


def create_by_arxiv(arxiv, db):
    """
    Create a new resource identified by its arXiv eprint ID, if it does not
    exist.

    :param arxiv: The arXiv eprint ID.
    :param db: A database session.
    :returns: ``None`` if insertion failed, the ``Paper`` object otherwise.
    """
    paper = database.Paper(arxiv_id=arxiv)

    # Try to fetch an arXiv id
    doi = arxiv.get_doi(arxiv)
    if doi:
        paper.doi = doi

    # Add it to the database
    try:
        db.add(paper)
        db.flush()
    except IntegrityError:
        # Unique constraint violation, paper already exists
        db.rollback()
        return None

    # Return the paper
    return paper