Basic API to put and fetch some papers

database.py

@@ -0,0 +1,40 @@
+"""
+This file contains the database schema in SQLAlchemy format.
+"""
+from sqlalchemy import Column, Integer, String
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()
+
+
+class Paper(Base):
+    __tablename__ = 'papers'
+    id = Column(Integer, primary_key=True)
+    doi = Column(String(), nullable=True, unique=True)
+    arxiv_id = Column(String(25), nullable=True, unique=True)
+
+    def __repr__(self):
+        return "<Paper(id='%d', doi='%s', arxiv_id='%s')>" % (
+            self.id,
+            self.doi,
+            self.arxiv_id,
+        )
+
+    def json_api_repr(self):
+        """
+        Dict to dump for the JSON API.
+        """
+        return {
+            "types": self.__tablename__,
+            "id": self.id,
+            "attributes": {
+                "doi": self.doi,
+                "arxiv_id": self.arxiv_id,
+            },
+            "links": {
+                "self": "/papers/%d" % (self.id,)
+            },
+            "relationships": {
+                # TODO
+            }
+        }

fetch_references.py

@@ -15,4 +15,4 @@ if __name__ == "__main__":
     if os.path.isfile(sys.argv[1]):
         pprint.pprint(bbl.get_dois(sys.argv[1]))
     else:
-        pprint.pprint(arxiv.get_dois(sys.argv[1]))
+        pprint.pprint(arxiv.get_cited_dois(sys.argv[1]))

main.py

@@ -1,31 +1,56 @@
 #!/usr/bin/env python3
-from bottle import get, post, run
+import bottle
 from bottle.ext import sqlalchemy
-from sqlalchemy import create_engine, Column, Integer, Sequence, String
-from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy import create_engine, event
+from sqlalchemy.engine import Engine
+
+import database
+import routes
+
+# Initialize db and include the SQLAlchemy plugin in bottle
+engine = create_engine('sqlite:///:memory:', echo=True)
+
+app = bottle.Bottle()
+plugin = sqlalchemy.Plugin(
+    # SQLAlchemy engine created with create_engine function.
+    engine,
+    # SQLAlchemy metadata, required only if create=True.
+    database.Base.metadata,
+    # Keyword used to inject session database in a route (default 'db').
+    keyword='db',
+    # If it is true, execute `metadata.create_all(engine)` when plugin is
+    # applied (default False).
+    create=True,
+    # If it is true, plugin commit changes after route is executed (default
+    # True).
+    commit=True,
+    # If it is true and keyword is not defined, plugin uses **kwargs argument
+    # to inject session database (default False).
+    use_kwargs=False
+)
+
+app.install(plugin)
 
 
-@get("/doi/<doi:path>")
-def doi(doi):
-    """
-    GET /doi/<DOI>
-
-    {}
-    """
-    # TODO
-    pass
+# Auto enable foreign keys for SQLite
+@event.listens_for(Engine, "connect")
+def set_sqlite_pragma(dbapi_connection, connection_record):
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.close()
 
 
-@post("/doi/<doi:path>")
-def doi_post(doi):
-    """
-    POST /doi/<DOI>
+# Routes
+app.get("/papers", callback=routes.get.fetch_papers)
+app.get("/papers/<id:int>", callback=routes.get.fetch_by_id)
 
-    {}
-    """
-    # TODO
-    pass
+# TODO: Fetch relationships
+
+
+app.post("/papers", callback=routes.post.create_paper)
+
+# TODO: Update relationships
 
 
 if __name__ == "__main__":
-    run(host='localhost', port=8080, debug=True)
+    app.run(host='localhost', port=8080, debug=True)

reference_fetcher/arxiv.py

@@ -4,6 +4,7 @@ This file contains all the arXiv-specific functions.
 import io
 import requests
 import tarfile
+import xml.etree.ElementTree
 
 from . import bbl
 
@@ -38,7 +39,7 @@ def bbl_from_arxiv(eprint):
     return bbl_files
 
 
-def get_dois(eprint):
+def get_cited_dois(eprint):
     """
     Get the .bbl files (if any) of a given preprint.
 
@@ -52,3 +53,46 @@ def get_dois(eprint):
     for bbl_file in bbl_files:
         dois.update(bbl.get_dois(bbl_file))
     return dois
+
+
+def get_arxiv_eprint_from_doi(doi):
+    """
+    Get the arXiv eprint id for a given DOI.
+
+    Params:
+        - doi is the DOI of the resource to look for.
+
+    Returns the arXiv eprint id, or None if not found.
+    """
+    r = requests.get("http://export.arxiv.org/api/query",
+                     params={
+                         "search_query": "doi:%s" % (doi,),
+                         "max_results": 1
+                     })
+    e = xml.etree.ElementTree.fromstring(r.content)
+    for entry in e.iter("{http://www.w3.org/2005/Atom}entry"):
+        id = entry.find("{http://www.w3.org/2005/Atom}id").text
+        return id.replace("http://arxiv.org/abs/", "")
+    return None
+
+
+def get_doi(eprint):
+    """
+    Get the associated DOI for a given arXiv eprint.
+
+    Params:
+        - eprint is the arXiv eprint id.
+
+    Returns the DOI if any, or None.
+    """
+    r = requests.get("http://export.arxiv.org/api/query",
+                     params={
+                         "id_list": eprint,
+                         "max_results": 1
+                     })
+    e = xml.etree.ElementTree.fromstring(r.content)
+    for entry in e.iter("{http://www.w3.org/2005/Atom}entry"):
+        doi = entry.find("{http://arxiv.org/schemas/atom}doi")
+        if doi is not None:
+            return doi.text
+    return None

routes/__init__.py

@@ -0,0 +1,4 @@
+from . import get
+from . import post
+
+__all__ = ["get", "post"]

routes/get.py

@@ -0,0 +1,161 @@
+"""
+This file contains GET routes methods.
+"""
+import bottle
+
+import database
+import tools
+
+
+def fetch_papers(db):
+    """
+    Fetch all matching papers.
+
+    ```
+    GET /papers
+    Accept: application/vnd.api+json
+    ```
+
+    Filtering is possible using `id=ID`, `doi=DOI`, `arxiv_id=ARXIV_ID` or any
+    combination of these GET parameters. Other parameters are ignored.
+
+    ```
+    {
+        "data": [
+            {
+                "type": "papers",
+                "id": 1,
+                "attributes": {
+                    "doi": "TODO",
+                    "arxiv_id": "TODO"
+                },
+                "links": {
+                    "self": "TODO"
+                },
+                "relationships": {
+                }
+            }
+        ]
+    }
+    ```
+    """
+    filters = {k: bottle.request.params[k]
+               for k in bottle.request.params
+               if k in ["id", "doi", "arxiv_id"]}
+    resources = db.query(database.Paper).filter_by(**filters).all()
+    if resources:
+        return tools.pretty_json({
+            "data": [resource.json_api_repr() for resource in resources]
+        })
+    return bottle.HTTPError(404, "Not found")
+
+
+def fetch_by_id(id, db):
+    """
+    Fetch a resource identified by its internal id.
+
+    ```
+    GET /id/<id>
+    Accept: application/vnd.api+json
+    ```
+
+    ```
+    {
+        "data": {
+            {
+                "type": "papers",
+                "id": 1,
+                "attributes": {
+                    "doi": "TODO",
+                    "arxiv_id": "TODO"
+                },
+                "links": {
+                    "self": "TODO"
+                },
+                "relationships": {
+                }
+            }
+        }
+    }
+    ```
+    """
+    resource = db.query(database.Paper).filter_by(id=id).first()
+    if resource:
+        return tools.pretty_json({
+            "data": resource.json_api_repr()
+        })
+    return bottle.HTTPError(404, "Not found")
+
+
+def fetch_by_doi(doi, db):
+    """
+    Fetch a resource identified by its DOI.
+
+    ```
+    GET /doi/<DOI>
+    Accept: application/vnd.api+json
+    ```
+
+    ```
+    {
+        "data": {
+            {
+                "type": "papers",
+                "id": 1,
+                "attributes": {
+                    "doi": "TODO",
+                    "arxiv_id": "TODO"
+                },
+                "links": {
+                    "self": "TODO"
+                },
+                "relationships": {
+                }
+            }
+        }
+    }
+    ```
+    """
+    resource = db.query(database.Paper).filter_by(doi=doi).first()
+    if resource:
+        return tools.pretty_json({
+            "data": resource.json_api_repr()
+        })
+    return bottle.HTTPError(404, "Not found")
+
+
+def fetch_by_arxiv(arxiv, db):
+    """
+    Fetch a resource identified by its arXiv eprint ID.
+
+    ```
+    GET /arxiv/<arxiv_eprint_id>
+    Accept: application/vnd.api+json
+    ```
+
+    ```
+    {
+        "data": {
+            {
+                "type": "papers",
+                "id": 1,
+                "attributes": {
+                    "doi": "TODO",
+                    "arxiv_id": "TODO"
+                },
+                "links": {
+                    "self": "TODO"
+                },
+                "relationships": {
+                }
+            }
+        }
+    }
+    ```
+    """
+    resource = db.query(database.Paper).filter_by(arxiv_id=arxiv).first()
+    if resource:
+        return tools.pretty_json({
+            "data": resource.json_api_repr()
+        })
+    return bottle.HTTPError(404, "Not found")

routes/post.py

@@ -0,0 +1,113 @@
+"""
+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.
+
+    ```
+    POST /papers
+    Content-Type: application/vnd.api+json
+    Accept: application/vnd.api+json
+
+    {
+        "data": {
+            "doi": "DOI",
+            // OR
+            "arxiv_id": "ARXIV_ID"
+        }
+    }
+    ```
+
+    ```
+    {} TODO
+    ```
+    """
+    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()
+    }
+    # Note: Return a 202 as the resource has been accepted but is not yet
+    # processed, especially since its relationships have not yet been fetched.
+    # TODO: Redirection
+    return bottle.HTTPResponse(status=202, body=tools.pretty_json(response))
+
+
+def create_by_doi(doi, db):
+    """
+    Create a new resource identified by its DOI, if it does not exist.
+
+    Return 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.
+
+    Return 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

tools.py

@@ -0,0 +1,14 @@
+"""
+Various utility functions.
+"""
+import json
+
+
+def pretty_json(data):
+    """
+    Return pretty printed JSON-formatted string.
+    """
+    return json.dumps(data,
+                      sort_keys=True,
+                      indent=4,
+                      separators=(',', ': '))