querying.py

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"""

connection class translates either a connection string for sqlite, oracle of frontier into a connection object.
Also sets up ORM with SQLAlchemy.

connection class can also take a pre-constructed engine - useful for web services.

"""

import sqlalchemy
from sqlalchemy import create_engine, text, or_
from sqlalchemy.orm import sessionmaker
from sqlalchemy.pool import NullPool
import datetime
from data_sources import json_data_node
from copy import deepcopy
import models
import traceback
import os
import netrc
import sys

class connection(object):
    engine = None
    connection = None
    session = None
    connection_data = None
    netrc_authenticators = None
    secrets = None
    """

    Given a connection string, parses the connection string and connects.

    """
    def __init__(self, connection_data, mode=None, map_blobs=False, secrets=None, pooling=False):

        self._pooling = pooling

        # add querying utility properties
        # these must belong to the connection since the way in which their values are handled
        # depends on the database being connected to.
        self.range = models.Range
        self.radius = models.Radius
        self.regexp = models.RegExp
        self.regexp.connection_object = self

        if type(connection_data) in [str, unicode]:
            # if we've been given a connection string, process it
            self.connection_data = new_connection_dictionary(connection_data, secrets=secrets, mode=mode)
            self.schema = self.connection_data.get("schema") if self.connection_data.get("schema") != None else ""

            self.range.database_type = self.connection_data["host"]
            self.radius.database_type = self.connection_data["host"]
            self.regexp.database_type = self.connection_data["host"]
        else:
            self.connection_data = connection_data
            # assume we have an engine
            # we need to take the string representation so we know which type of db we're aiming at
            engine_string = str(connection_data)
            db_type = None
            if "oracle" in engine_string:
                db_type = "oracle"
            elif "frontier" in engine_string:
                db_type = "frontier"
            elif "sqlite" in engine_string:
                db_type = "sqlite"

            self.range.database_type = db_type
            self.radius.database_type = db_type
            self.regexp.database_type = db_type

        import models as ms
        self.models = ms.generate(map_blobs)
        #self.base = self.models["Base"]

    def setup(self):
        """
        Setup engine with given credentials from netrc file, and make a session maker.
        """

        if isinstance(self.connection_data, dict):
            self.engine = engine_from_dictionary(self.connection_data, pooling=self._pooling)
        else:
            # we've been given an engine by the user
            # use it as the engine
            self.engine = self.connection_data

        self.sessionmaker = sessionmaker(bind=self.engine)
        self.session = self.sessionmaker()
        self.factory = factory(self)

        # assign correct schema for database name to each model
        tmp_models_dict = {}
        for key in self.models:
            if self.models[key].__class__ == sqlalchemy.ext.declarative.api.DeclarativeMeta\
               and str(self.models[key].__name__) != "Base":

                if isinstance(self.connection_data, dict):
                    # we can only extract the secrets and schema individuall
                    # if we were given a dictionary...  if we were given an engine
                    # we can't do this without parsing the connection string from the engine
                    # - a wide range of which it will be difficult to support!
                    self.models[key].__table__.schema = self.connection_data["schema"]
                    self.models[key].secrets = self.connection_data["secrets"]

                self.models[key].session = self.session
                # isn't used anywhere - comment it out for now
                #self.models[key].authentication = self.netrc_authenticators
                self.models[key].connection = self
                tmp_models_dict[key.lower()] = self.models[key]
                tmp_models_dict[key.lower()].empty = False

        self.models = tmp_models_dict

        return self

    @staticmethod
    def _get_CMS_frontier_connection_string(database):
        try:
            import subprocess
            return subprocess.Popen(['cmsGetFnConnect', 'frontier://%s' % database], stdout = subprocess.PIPE).communicate()[0].strip()
        except:
            raise Exception("Frontier connections can only be constructed when inside a CMSSW environment.")

    @staticmethod
    def _cms_frontier_string(database, schema="cms_conditions"):
        """
        Get database string for frontier.
        """
        import urllib
        return 'oracle+frontier://@%s/%s' % (urllib.quote_plus(connection._get_CMS_frontier_connection_string(database)), schema)

    @staticmethod
    def _cms_oracle_string(user, pwd, db_name):
        """
        Get database string for oracle.
        """
        return 'oracle://%s:%s@%s' % (user, pwd, db_name)

    @staticmethod
    def build_oracle_url(user, pwd, db_name):
        """
        Build the connection url, and get credentials from self.secrets dictionary.
        """

        database_url = connection._cms_oracle_string(user, pwd, db_name)

        try:
            url = sqlalchemy.engine.url.make_url(database_url)
            if url.password is None:
                url.password = pwd
        except sqlalchemy.exc.ArgumentError:
            url = sqlalchemy.engine.url.make_url('sqlite:///%s' % db_name)
        return url

    @staticmethod
    def build_frontier_url(db_name, schema):
        database_url = connection._cms_frontier_string(db_name, schema)

        try:
            url = sqlalchemy.engine.url.make_url(database_url)
        except sqlalchemy.exc.ArgumentError:
            """
            Is this needed for a use case?
            """
            url = sqlalchemy.engine.url.make_url('sqlite:///%s' % db_name)
        return url

    # currently just commits and closes the current session (ends transaction, closes connection)
    # may do other things later
    def tear_down(self):
        try:
            self.session.commit()
            self.close_session()
        except:
            return "Couldn't tear down connection on engine %s." % str(self.engine)

    def close_session(self):
        self.session.close()
        return True

    def hard_close(self):
        self.engine.dispose()
        return True

    # get model based on given model name
    def model(self, model_name):
        if model_name.__class__ == sqlalchemy.ext.declarative.api.DeclarativeMeta:
            model_name = model_name.__name__
        model_name = model_name.replace("_", "")
        return self.models[model_name]

    # model should be the class the developer wants to be instantiated
    # pk_to_value maps primary keys to values
    def object(self, model, pk_to_value):
        if self.session == None:
            return None
        model_data = self.session.query(model)
        for pk in pk_to_value:
            model_data = model_data.filter(model.__dict__[pk] == pk_to_value[pk])
        return model_data.first()

    def global_tag(self, **pkargs):
        return self.factory.object("globaltag", **pkargs)

    def global_tag_map(self, **pkargs):
        return self.factory.object("globaltagmap", **pkargs)

    """def global_tag_map_request(self, **pkargs):
        return self.factory.object("globaltagmaprequest", **pkargs)"""

    def tag(self, **pkargs):
        return self.factory.object("tag", **pkargs)

    def iov(self, **pkargs):
        return self.factory.object("iov", **pkargs)

    def payload(self, **pkargs):
        return self.factory.object("payload", **pkargs)

    """def record(self, **pkargs):
        return self.factory.object("record", **pkargs)"""

    # adds %% at the beginning and end so LIKE in SQL searches all of the string
    def _oracle_match_format(self, string):
        return "%%%s%%" % string

    # returns dictionary mapping object type to a list of all objects found in the search
    def search_everything(self, string, amount=10):
        string = self._oracle_match_format(string)

        gt = self.model("globaltag")
        global_tags = self.session.query(gt).filter(or_(
                                                        gt.name.ilike(string),
                                                        gt.description.ilike(string),
                                                        gt.release.ilike(string)
                                                    )).limit(amount)
        tag = self.model("tag")
        tags = self.session.query(tag).filter(or_(
                                                    tag.name.ilike(string),
                                                    tag.object_type.ilike(string),
                                                    tag.description.ilike(string))
                                                ).limit(amount)
        iov = self.model("iov")
        iovs = self.session.query(iov).filter(or_(
                                                    iov.tag_name.ilike(string),
                                                    iov.since.ilike(string),
                                                    iov.payload_hash.ilike(string),
                                                    iov.insertion_time.ilike(string)
                                                )).limit(amount)
        payload = self.model("payload")
        payloads = self.session.query(payload).filter(or_(
                                                            payload.hash.ilike(string),
                                                            payload.object_type.ilike(string),
                                                            payload.insertion_time.ilike(string)
                                                        )).limit(amount)

        return json_data_node.make({
            "global_tags" : global_tags.all(),
            "tags" : tags.all(),
            "iovs" : iovs.all(),
            "payloads" : payloads.all()
        })

    def write(self, object):
        new_object = models.session_independent_object(object, schema=self.schema)
        self.session.add(new_object)
        return new_object

    def commit(self):
        try:
            self.session.commit()
        except:
            traceback.print_exc()
            self.session.rollback()

    def write_and_commit(self, object):
        if isinstance(object, list):
            for item in object:
                self.write_and_commit(item)
        else:
            # should be changed to deal with errors - add them to exception handling if they appear
            self.write(object)
            self.commit()

    def rollback(self):
        try:
            self.session.rollback()
        except:
            traceback.print_exc()
            print("Session couldn't be rolled back.")

class factory():
    """
    Contains methods for creating objects.
    """
    def __init__(self, connection):
        self.connection = connection

    # class_name is the class name of the model to be used
    # pkargs is a dictionary of keyword arguments used as primary key values
    # this dictionary will be used to populate the object of type name class_name
    def object(self, class_name, **pkargs):
        from data_sources import json_list
        from models import apply_filters
        # get the class that self.connection holds from the class name
        model = self.connection.model(class_name)

        if self.connection.session == None:
            return None

        # query for the ORM object, and return the appropriate object (None, CondDBFW object, or json_list)
        model_data = self.connection.session.query(model)
        if len(pkargs.items()) != 0:
            # apply the filters defined in **kwargs
            model_data = apply_filters(model_data, model, **pkargs)
            amount = pkargs["amount"] if "amount" in pkargs.keys() else None
            model_data = model_data.limit(amount)
            if model_data.count() > 1:
                # if we have multiple objects, return a json_list
                return json_list(model_data.all())
            elif model_data.count() == 1:
                # if we have a single object, return that object
                return model_data.first()
            else:
                # if we have no objects returned, return None
                return None
        else:
            # no column arguments were given, so return an empty object
            new_object = model()
            new_object.empty = True
            return new_object

def _get_netrc_data(netrc_file, key):
    """
    Returns a dictionary {login : ..., account : ..., password : ...}
    """
    try:
        headers = ["login", "account", "password"]
        authenticator_tuple = netrc.netrc(netrc_file).authenticators(key)
        if authenticator_tuple == None:
            raise Exception("netrc file must contain key '%s'." % key)
    except:
        raise Exception("Couldn't get credentials from netrc file.")
    return dict(zip(headers, authenticator_tuple))

def new_connection_dictionary(connection_data, secrets=None, mode="r"):
    """
    Function used to construct connection data dictionaries - internal to framework.
    """
    frontier_str_length = len("frontier://")
    sqlite_str_length = len("sqlite://")
    #sqlite_file_str_length = len("sqlite_file://")
    oracle_str_length = len("oracle://")

    if type(connection_data) in [str, unicode] and connection_data[0:frontier_str_length] == "frontier://":
        """
        frontier://database_name/schema
        """
        db_name = connection_data[frontier_str_length:].split("/")[0]
        schema = connection_data[frontier_str_length:].split("/")[1]
        connection_data = {}
        connection_data["database_name"] = db_name
        connection_data["schema"] = schema
        connection_data["host"] = "frontier"
        connection_data["secrets"] = None
    elif type(connection_data) in [str, unicode] and connection_data[0:sqlite_str_length] == "sqlite://":
        """
        sqlite://database_file_name
        """
        # for now, just support "sqlite://" format for sqlite connection strings
        db_name = connection_data[sqlite_str_length:]
        schema = ""
        connection_data = {}
        connection_data["database_name"] = os.path.abspath(db_name)
        connection_data["schema"] = schema
        connection_data["host"] = "sqlite"
        connection_data["secrets"] = None
    elif type(connection_data) in [str, unicode] and connection_data[0:oracle_str_length] == "oracle://":
        """
        oracle://account:password@database_name
        or
        oracle://database_name/schema (requires a separate method of authentication - either dictionary or netrc)
        """
        new_connection_string = connection_data[oracle_str_length:]

        if ":" in new_connection_string:
            # the user has given a password - usually in the case of the db upload service
            database_name = new_connection_string[new_connection_string.index("@")+1:]
            schema_name = new_connection_string[0:new_connection_string.index(":")]
            # set username based on connection string
            username = new_connection_string[0:new_connection_string.index(":")]
            password = new_connection_string[new_connection_string.index(":")+1:new_connection_string.index("@")]
        else:
            mode_to_netrc_key_suffix = {"r" : "read", "w" : "write"}
            database_name = new_connection_string[0:new_connection_string.index("/")]
            schema_name = new_connection_string[new_connection_string.index("/")+1:]
            if secrets == None:
                username = str(raw_input("Enter the username you want to connect to the schema '%s' with: " % (schema_name)))
                password = str(raw_input("Enter the password for the user '%s' in database '%s': " % (username, database_name)))
            else:
                if isinstance(secrets, str):
                    netrc_key = "%s/%s/%s" % (database_name, schema_name, mode_to_netrc_key_suffix[mode])
                    netrc_data = _get_netrc_data(secrets, key=netrc_key)
                    # take the username from the netrc entry corresponding to the mode the database is opened in
                    # eg, if the user has given mode="read", the database_name/schema_name/read entry will be taken
                    username = netrc_data["login"]
                    password = netrc_data["password"]
                elif isinstance(secrets, dict):
                    username = secrets["user"]
                    password = secrets["password"]
                else:
                    raise Exception("Invalid type given for secrets.  Either an str or a dict must be given.")

        #print("Connected to database %s, schema %s, with username %s." % (database_name, schema_name, username))

        connection_data = {}
        connection_data["database_name"] = database_name
        connection_data["schema"] = schema_name
        connection_data["password"] = password
        connection_data["host"] = "oracle"
        connection_data["secrets"] = {"login" : username, "password" : password}

    return connection_data

def engine_from_dictionary(dictionary, pooling=True):
    if dictionary["host"] != "sqlite":
        if dictionary["host"] != "frontier":
            # probably oracle
            # if not frontier, we have to authenticate
            user = dictionary["secrets"]["login"]
            pwd = dictionary["secrets"]["password"]
            # set max label length for oracle
            if pooling:
                return create_engine(connection.build_oracle_url(user, pwd, dictionary["database_name"]), label_length=6)
            else:
                return create_engine(connection.build_oracle_url(user, pwd, dictionary["database_name"]), label_length=6, poolclass=NullPool)
        else:
            # if frontier, no need to authenticate
            # set max label length for frontier
            if pooling:
                return create_engine(connection.build_frontier_url(dictionary["database_name"], dictionary["schema"]), label_length=6)
            else:
                return create_engine(connection.build_frontier_url(dictionary["database_name"], dictionary["schema"]), label_length=6, poolclass=NullPool)
    else:
        # if host is sqlite, making the url is easy - no authentication
        return create_engine("sqlite:///%s" % dictionary["database_name"])


def connect(connection_data, mode="r", map_blobs=False, secrets=None, pooling=True):
    """
    Utility method for user - set up a connection object.
    """
    con = connection(connection_data=connection_data, mode=mode, map_blobs=map_blobs, secrets=secrets, pooling=pooling)
    con = con.setup()
    return con