Is there a simple way to iterate over column name and value pairs?
My version of sqlalchemy is 0.5.6
Here is the sample code where I tried using dict(row), but it throws exception , TypeError: 'User' object is not iterable
import sqlalchemy
from sqlalchemy import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
print "sqlalchemy version:",sqlalchemy.__version__
engine = create_engine('sqlite:///:memory:', echo=False)
metadata = MetaData()
users_table = Table('users', metadata,
Column('id', Integer, primary_key=True),
Column('name', String),
)
metadata.create_all(engine)
class User(declarative_base()):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String)
def __init__(self, name):
self.name = name
Session = sessionmaker(bind=engine)
session = Session()
user1 = User("anurag")
session.add(user1)
session.commit()
# uncommenting next line throws exception 'TypeError: 'User' object is not iterable'
#print dict(user1)
# this one also throws 'TypeError: 'User' object is not iterable'
for u in session.query(User).all():
print dict(u)
Running this code on my system outputs:
sqlalchemy version: 0.5.6
Traceback (most recent call last):
File "untitled-1.py", line 37, in <module>
print dict(u)
TypeError: 'User' object is not iterable
This question is related to
python
sqlalchemy
I couldn't get a good answer so I use this:
def row2dict(row):
d = {}
for column in row.__table__.columns:
d[column.name] = str(getattr(row, column.name))
return d
Edit: if above function is too long and not suited for some tastes here is a one liner (python 2.7+)
row2dict = lambda r: {c.name: str(getattr(r, c.name)) for c in r.__table__.columns}
My take utilizing (too many?) dictionaries:
def serialize(_query):
#d = dictionary written to per row
#D = dictionary d is written to each time, then reset
#Master = dictionary of dictionaries; the id Key (int, unique from database) from D is used as the Key for the dictionary D entry in Master
Master = {}
D = {}
x = 0
for u in _query:
d = u.__dict__
D = {}
for n in d.keys():
if n != '_sa_instance_state':
D[n] = d[n]
x = d['id']
Master[x] = D
return Master
Running with flask (including jsonify) and flask_sqlalchemy to print outputs as JSON.
Call the function with jsonify(serialize()).
Works with all SQLAlchemy queries I've tried so far (running SQLite3)
def to_dict(row):
return {column.name: getattr(row, row.__mapper__.get_property_by_column(column).key) for column in row.__table__.columns}
for u in session.query(User).all():
print(to_dict(u))
This function might help. I can't find better solution to solve problem when attribute name is different then column names.
class User(object):
def to_dict(self):
return dict([(k, getattr(self, k)) for k in self.__dict__.keys() if not k.startswith("_")])
That should work.
as @balki mentioned:
The _asdict() method can be used if you're querying a specific field because it is returned as a KeyedTuple.
In [1]: foo = db.session.query(Topic.name).first()
In [2]: foo._asdict()
Out[2]: {'name': u'blah'}
Whereas, if you do not specify a column you can use one of the other proposed methods - such as the one provided by @charlax. Note that this method is only valid for 2.7+.
In [1]: foo = db.session.query(Topic).first()
In [2]: {x.name: getattr(foo, x.name) for x in foo.__table__.columns}
Out[2]: {'name': u'blah'}
Assuming the following functions will be added to the class User the following will return all key-value pairs of all columns:
def columns_to_dict(self):
dict_ = {}
for key in self.__mapper__.c.keys():
dict_[key] = getattr(self, key)
return dict_
unlike the other answers all but only those attributes of the object are returned which are Column attributes at class level of the object. Therefore no _sa_instance_state or any other attribute SQLalchemy or you add to the object are included. Reference
EDIT: Forget to say, that this also works on inherited Columns.
hybrid_propery extentionIf you also want to include hybrid_property attributes the following will work:
from sqlalchemy import inspect
from sqlalchemy.ext.hybrid import hybrid_property
def publics_to_dict(self) -> {}:
dict_ = {}
for key in self.__mapper__.c.keys():
if not key.startswith('_'):
dict_[key] = getattr(self, key)
for key, prop in inspect(self.__class__).all_orm_descriptors.items():
if isinstance(prop, hybrid_property):
dict_[key] = getattr(self, key)
return dict_
I assume here that you mark Columns with an beginning _ to indicate that you want to hide them, either because you access the attribute by an hybrid_property or you simply do not want to show them. Reference
Tipp all_orm_descriptors also returns hybrid_method and AssociationProxy if you also want to include them.
Every answer (like 1, 2 ) which based on the __dict__ attribute simply returns all attributes of the object. This could be much more attributes then you want. Like I sad this includes _sa_instance_state or any other attribute you define on this object.
Every answer (like 1, 2 ) which is based on the dict() function only works on SQLalchemy row objects returned by session.execute() not on the classes you define to work with, like the class User from the question.
The solving answer which is based on row.__table__.columns will definitely not work. row.__table__.columns contains the column names of the SQL Database. These can only be equal to the attributes name of the python object. If not you get an AttributeError.
For answers (like 1, 2 ) based on class_mapper(obj.__class__).mapped_table.c it is the same.
rows have an _asdict() function which gives a dict
In [8]: r1 = db.session.query(Topic.name).first()
In [9]: r1
Out[9]: (u'blah')
In [10]: r1.name
Out[10]: u'blah'
In [11]: r1._asdict()
Out[11]: {'name': u'blah'}
I've found this post because I was looking for a way to convert a SQLAlchemy row into a dict. I'm using SqlSoup... but the answer was built by myself, so, if it could helps someone here's my two cents:
a = db.execute('select * from acquisizioni_motes')
b = a.fetchall()
c = b[0]
# and now, finally...
dict(zip(c.keys(), c.values()))
from sqlalchemy.orm import class_mapper
def asdict(obj):
return dict((col.name, getattr(obj, col.name))
for col in class_mapper(obj.__class__).mapped_table.c)
Here is a super simple way of doing it
row2dict = lambda r: dict(r.items())
I don't have much experience with this, but the following seems to work for what I'm doing:
dict(row)
This seems too simple (compared to the other answers here). What am I missing?
In most scenarios, column name is fit for them. But maybe you write the code like follows:
class UserModel(BaseModel):
user_id = Column("user_id", INT, primary_key=True)
email = Column("user_email", STRING)
the column.name "user_email" while the field name is "email", the column.name could not work well as before.
I am a newly minted Python programmer and ran into problems getting to JSON with Joined tables. Using information from the answers here I built a function to return reasonable results to JSON where the table names are included avoiding having to alias, or have fields collide.
Simply pass the result of a session query:
test = Session().query(VMInfo, Customer).join(Customer).order_by(VMInfo.vm_name).limit(50).offset(10)
json = sqlAl2json(test)
def sqlAl2json(self, result):
arr = []
for rs in result.all():
proc = []
try:
iterator = iter(rs)
except TypeError:
proc.append(rs)
else:
for t in rs:
proc.append(t)
dict = {}
for p in proc:
tname = type(p).__name__
for d in dir(p):
if d.startswith('_') | d.startswith('metadata'):
pass
else:
key = '%s_%s' %(tname, d)
dict[key] = getattr(p, d)
arr.append(dict)
return json.dumps(arr)
For the sake of everyone and myself, here is how I use it:
def run_sql(conn_String):
output_connection = engine.create_engine(conn_string, poolclass=NullPool).connect()
rows = output_connection.execute('select * from db1.t1').fetchall()
return [dict(row) for row in rows]
Refer to Alex Brasetvik's Answer, you can use one line of code to solve the problem
row_as_dict = [dict(row) for row in resultproxy]
Under the comment section of Alex Brasetvik's Answer, zzzeek the creator of SQLAlchemy stated this is the "Correct Method" for the problem.
A solution that works with inherited classes too:
from itertools import chain
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class Mixin(object):
def as_dict(self):
tables = [base.__table__ for base in self.__class__.__bases__ if base not in [Base, Mixin]]
tables.append(self.__table__)
return {c.name: getattr(self, c.name) for c in chain.from_iterable([x.columns for x in tables])}
You could try to do it in this way.
for u in session.query(User).all():
print(u._asdict())
It use a built-in method in the query object that return a dictonary object of the query object.
references: https://docs.sqlalchemy.org/en/latest/orm/query.html
Old question, but since this the first result for "sqlalchemy row to dict" in Google it deserves a better answer.
The RowProxy object that SqlAlchemy returns has the items() method: http://docs.sqlalchemy.org/en/latest/core/connections.html#sqlalchemy.engine.RowProxy.items
It simply returns a list of (key, value) tuples. So one can convert a row to dict using the following:
In Python <= 2.6:
rows = conn.execute(query)
list_of_dicts = [dict((key, value) for key, value in row.items()) for row in rows]
In Python >= 2.7:
rows = conn.execute(query)
list_of_dicts = [{key: value for (key, value) in row.items()} for row in rows]
As per @zzzeek in comments:
note that this is the correct answer for modern versions of SQLAlchemy, assuming "row" is a core row object, not an ORM-mapped instance.
for row in resultproxy:
row_as_dict = dict(row)
Two ways:
1.
for row in session.execute(session.query(User).statement):
print(dict(row))
2.
selected_columns = User.__table__.columns
rows = session.query(User).with_entities(*selected_columns).all()
for row in rows :
print(row._asdict())
We can get a list of object in dict:
def queryset_to_dict(query_result):
query_columns = query_result[0].keys()
res = [list(ele) for ele in query_result]
dict_list = [dict(zip(query_columns, l)) for l in res]
return dict_list
query_result = db.session.query(LanguageMaster).all()
dictvalue=queryset_to_dict(query_result)
Here is how Elixir does it. The value of this solution is that it allows recursively including the dictionary representation of relations.
def to_dict(self, deep={}, exclude=[]):
"""Generate a JSON-style nested dict/list structure from an object."""
col_prop_names = [p.key for p in self.mapper.iterate_properties \
if isinstance(p, ColumnProperty)]
data = dict([(name, getattr(self, name))
for name in col_prop_names if name not in exclude])
for rname, rdeep in deep.iteritems():
dbdata = getattr(self, rname)
#FIXME: use attribute names (ie coltoprop) instead of column names
fks = self.mapper.get_property(rname).remote_side
exclude = [c.name for c in fks]
if dbdata is None:
data[rname] = None
elif isinstance(dbdata, list):
data[rname] = [o.to_dict(rdeep, exclude) for o in dbdata]
else:
data[rname] = dbdata.to_dict(rdeep, exclude)
return data
The expression you are iterating through evaluates to list of model objects, not rows. So the following is correct usage of them:
for u in session.query(User).all():
print u.id, u.name
Do you realy need to convert them to dicts? Sure, there is a lot of ways, but then you don't need ORM part of SQLAlchemy:
result = session.execute(User.__table__.select())
for row in result:
print dict(row)
Update: Take a look at sqlalchemy.orm.attributes module. It has a set of functions to work with object state, that might be useful for you, especially instance_dict().
Return the contents of this :class:.KeyedTuple as a dictionary
In [46]: result = aggregate_events[0]
In [47]: type(result)
Out[47]: sqlalchemy.util._collections.result
In [48]: def to_dict(query_result=None):
...: cover_dict = {key: getattr(query_result, key) for key in query_result.keys()}
...: return cover_dict
...:
...:
In [49]: to_dict(result)
Out[49]:
{'calculate_avg': None,
'calculate_max': None,
'calculate_min': None,
'calculate_sum': None,
'dataPointIntID': 6,
'data_avg': 10.0,
'data_max': 10.0,
'data_min': 10.0,
'data_sum': 60.0,
'deviceID': u'asas',
'productID': u'U7qUDa',
'tenantID': u'CvdQcYzUM'}
With python 3.8+, we can do this with dataclass, and the asdict method that comes with it:
from dataclasses import dataclass, asdict
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import Column, String, Integer, create_engine
Base = declarative_base()
engine = create_engine('sqlite:///:memory:', echo=False)
@dataclass
class User(Base):
__tablename__ = 'users'
id: int = Column(Integer, primary_key=True)
name: str = Column(String)
email = Column(String)
def __init__(self, name):
self.name = name
self.email = '[email protected]'
Base.metadata.create_all(engine)
SessionMaker = sessionmaker(bind=engine)
session = SessionMaker()
user1 = User("anurag")
session.add(user1)
session.commit()
query_result = session.query(User).one() # type: User
print(f'{query_result.id=:}, {query_result.name=:}, {query_result.email=:}')
# query_result.id=1, query_result.name=anurag, [email protected]
query_result_dict = asdict(query_result)
print(query_result_dict)
# {'id': 1, 'name': 'anurag'}
The key is to use the @dataclass decorator, and annotate each column with its type (the : str part of the name: str = Column(String) line).
Also note that since the email is not annotated, it is not included in query_result_dict.
You may access the internal __dict__ of a SQLAlchemy object, like the following::
for u in session.query(User).all():
print u.__dict__
In SQLAlchemy v0.8 and newer, use the inspection system.
from sqlalchemy import inspect
def object_as_dict(obj):
return {c.key: getattr(obj, c.key)
for c in inspect(obj).mapper.column_attrs}
user = session.query(User).first()
d = object_as_dict(user)
Note that .key is the attribute name, which can be different from the column name, e.g. in the following case:
class_ = Column('class', Text)
This method also works for column_property.
You'll need it everywhere in your project, I apriciate @anurag answered it works fine. till this point I was using it, but it'll mess all your code and also wont work with entity change.
Rather try this, inherit your base query class in SQLAlchemy
from flask_sqlalchemy import SQLAlchemy, BaseQuery
class Query(BaseQuery):
def as_dict(self):
context = self._compile_context()
context.statement.use_labels = False
columns = [column.name for column in context.statement.columns]
return list(map(lambda row: dict(zip(columns, row)), self.all()))
db = SQLAlchemy(query_class=Query)
after that wherever you'll define your object "as_dict" method will be there.
To complete @Anurag Uniyal 's answer, here is a method that will recursively follow relationships:
from sqlalchemy.inspection import inspect
def to_dict(obj, with_relationships=True):
d = {}
for column in obj.__table__.columns:
if with_relationships and len(column.foreign_keys) > 0:
# Skip foreign keys
continue
d[column.name] = getattr(obj, column.name)
if with_relationships:
for relationship in inspect(type(obj)).relationships:
val = getattr(obj, relationship.key)
d[relationship.key] = to_dict(val) if val else None
return d
class User(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
first_name = Column(TEXT)
address_id = Column(Integer, ForeignKey('addresses.id')
address = relationship('Address')
class Address(Base):
__tablename__ = 'addresses'
id = Column(Integer, primary_key=True)
city = Column(TEXT)
user = User(first_name='Nathan', address=Address(city='Lyon'))
# Add and commit user to session to create ids
to_dict(user)
# {'id': 1, 'first_name': 'Nathan', 'address': {'city': 'Lyon'}}
to_dict(user, with_relationship=False)
# {'id': 1, 'first_name': 'Nathan', 'address_id': 1}
Following @balki answer, since SQLAlchemy 0.8 you can use _asdict(), available for KeyedTuple objects. This renders a pretty straightforward answer to the original question. Just, change in your example the last two lines (the for loop) for this one:
for u in session.query(User).all():
print u._asdict()
This works because in the above code u is an object of type class KeyedTuple, since .all() returns a list of KeyedTuple. Therefore it has the method _asdict(), which nicely returns u as a dictionary.
WRT the answer by @STB: AFAIK, anything that .all() returns is a list of KeypedTuple. Therefore, the above works either if you specify a column or not, as long as you are dealing with the result of .all() as applied to a Query object.
The 1.3 docs offer a very simple solution: KeyedTuple._asdict()
def to_array(rows):
return [r._asdict() for r in rows]
def query():
data = session.query(Table).all()
return to_array(data)
I have a variation on Marco Mariani's answer, expressed as a decorator. The main difference is that it'll handle lists of entities, as well as safely ignoring some other types of return values (which is very useful when writing tests using mocks):
@decorator
def to_dict(f, *args, **kwargs):
result = f(*args, **kwargs)
if is_iterable(result) and not is_dict(result):
return map(asdict, result)
return asdict(result)
def asdict(obj):
return dict((col.name, getattr(obj, col.name))
for col in class_mapper(obj.__class__).mapped_table.c)
def is_dict(obj):
return isinstance(obj, dict)
def is_iterable(obj):
return True if getattr(obj, '__iter__', False) else False
Python 3.6.8+
The builtin str() method automatically converts datetime.datetime objects to iso-8806-1.
print(json.dumps([dict(row.items()) for row in rows], default=str, indent=" "))
NOTE: The default func will only be applied to a value if there's an error so int and float values won't be converted... unless there's an error :).
You can convert sqlalchemy object to dictionary like this and return it as json/dictionary.
Helper functions:
import json
from collections import OrderedDict
def asdict(self):
result = OrderedDict()
for key in self.__mapper__.c.keys():
if getattr(self, key) is not None:
result[key] = str(getattr(self, key))
else:
result[key] = getattr(self, key)
return result
def to_array(all_vendors):
v = [ ven.asdict() for ven in all_vendors ]
return json.dumps(v)
Driver Function:
def all_products():
all_products = Products.query.all()
return to_array(all_products)
With this code you can also to add to your query "filter" or "join" and this work!
query = session.query(User)
def query_to_dict(query):
def _create_dict(r):
return {c.get('name'): getattr(r, c.get('name')) for c in query.column_descriptions}
return [_create_dict(r) for r in query]
if your models table column is not equie mysql column.
such as :
class People:
id: int = Column(name='id', type_=Integer, primary_key=True)
createdTime: datetime = Column(name='create_time', type_=TIMESTAMP,
nullable=False,
server_default=text("CURRENT_TIMESTAMP"),
default=func.now())
modifiedTime: datetime = Column(name='modify_time', type_=TIMESTAMP,
server_default=text("CURRENT_TIMESTAMP"),
default=func.now())
Need to use:
from sqlalchemy.orm import class_mapper
def asDict(self):
return {x.key: getattr(self, x.key, None) for x in
class_mapper(Application).iterate_properties}
if you use this way you can get modify_time and create_time both are None
{'id': 1, 'create_time': None, 'modify_time': None}
def to_dict(self):
return {c.name: getattr(self, c.name, None)
for c in self.__table__.columns}
Because Class Attributes name not equal with column store in mysql
Source: Stackoverflow.com