Using OR in SQLAlchemy

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Question :

Using OR in SQLAlchemy

I’ve looked through the docs and I cant seem to find out how to do an OR query in SQLAlchemy. I just want to do this query.

SELECT address FROM addressbook WHERE city='boston' AND (lastname='bulger' OR firstname='whitey')

Should be something like

addr = session.query(AddressBook).filter(City == "boston").filter(????)

Answer #1:

From the tutorial:

from sqlalchemy import or_
filter(or_(User.name == 'ed', User.name == 'wendy'))
Answered By: JiminyCricket

Answer #2:

SQLAlchemy overloads the bitwise operators &, | and ~ so instead of the ugly and hard-to-read prefix syntax with or_() and and_() (like in Bastien’s answer) you can use these operators:

.filter((AddressBook.lastname == 'bulger') | (AddressBook.firstname == 'whitey'))

Note that the parentheses are not optional due to the precedence of the bitwise operators.

So your whole query could look like this:

addr = session.query(AddressBook) 
    .filter(AddressBook.city == "boston") 
    .filter((AddressBook.lastname == 'bulger') | (AddressBook.firstname == 'whitey'))
Answered By: Bastien LĂ©onard

Answer #3:

or_() function can be useful in case of unknown number of OR query components.

For example, let’s assume that we are creating a REST service with few optional filters, that should return record if any of filters return true. On the other side, if parameter was not defined in a request, our query shouldn’t change. Without or_() function we must do something like this:

query = Book.query
if filter.title and filter.author:
    query = query.filter((Book.title.ilike(filter.title))|(Book.author.ilike(filter.author)))
else if filter.title:
    query = query.filter(Book.title.ilike(filter.title))
else if filter.author:
    query = query.filter(Book.author.ilike(filter.author))

With or_() function it can be rewritten to:

query = Book.query
not_null_filters = []
if filter.title:
    not_null_filters.append(Book.title.ilike(filter.title))
if filter.author:
    not_null_filters.append(Book.author.ilike(filter.author))

if len(not_null_filters) > 0:
    query = query.filter(or_(*not_null_filters))
Answered By: ThiefMaster

Answer #4:

This has been really helpful.
Here is my implementation for any given table:

def sql_replace(self, tableobject, dictargs):

    #missing check of table object is valid
    primarykeys = [key.name for key in inspect(tableobject).primary_key]

    filterargs = []
    for primkeys in primarykeys:
        if dictargs[primkeys] is not None:
            filterargs.append(getattr(db.RT_eqmtvsdata, primkeys) == dictargs[primkeys])
        else:
            return

    query = select([db.RT_eqmtvsdata]).where(and_(*filterargs))

    if self.r_ExecuteAndErrorChk2(query)[primarykeys[0]] is not None:
        # update
        filter = and_(*filterargs)
        query = tableobject.__table__.update().values(dictargs).where(filter)
        return self.w_ExecuteAndErrorChk2(query)

    else:
        query = tableobject.__table__.insert().values(dictargs)
        return self.w_ExecuteAndErrorChk2(query)

# example usage
inrow = {'eqmtvs_id': eqmtvsid, 'datetime': dtime, 'param_id': paramid}

self.sql_replace(tableobject=db.RT_eqmtvsdata, dictargs=inrow)
Answered By: Valar

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