Similar to Ruby's Mongoid, PyMODM is an ODM for Python that follows closely on Django's built-in ORM. Installing pymodm can be done via pip, as shown in the following code:
pip install pymodm
Then we need to edit settings.py and replace the database ENGINE with a dummy database, as shown in the following code:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.dummy'
}
}
Then we add our connection string anywhere in settings.py, as shown in the following code:
from pymodm import connect
connect("mongodb://localhost:27017/myDatabase", alias="MyApplication")
Here, we have to use a connection string that has the following structure:
mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]
Options have to be pairs of name=value with an & between each pair. Some interesting pairs are shown in the following table:
|
Name |
Description |
|
minPoolSize/maxPoolSize |
Minimum and maximum pool size for connections. |
|
w |
Write concern option. |
|
wtimeoutMS |
Timeout for write concern operations. |
|
Journal |
Journal options. |
|
readPreference |
Read preference to be used for replica sets. Available options are: primary, primaryPreferred, secondary, secondaryPreferred, nearest. |
|
maxStalenessSeconds |
Specifies, in seconds, how stale (data lagging behind master) a secondary can be before the client stops using it for read operations. |
|
SSL |
Using SSL to connect to the database. |
|
authSource |
Used in conjunction with username, this specifies the database associated with the user's credentials. When we use external authentication mechanisms, this should be $external for LDAP or Kerberos. |
|
authMechanism |
Authentication mechanism can be used for connections. Available options for MongoDB are: SCRAM-SHA-1, MONGODB-CR, MONGODB-X.509. MongoDB enterprise (paid version) offers two more options: GSSAPI (Kerberos), PLAIN (LDAP SASL) |
Model classes need to inherit from MongoModel. The following code shows what a sample class will look like:
from pymodm import MongoModel, fields
class User(MongoModel):
email = fields.EmailField(primary_key=True)
first_name = fields.CharField()
last_name = fields.CharField()
This has a User class with first_name, last_name, and email fields, where email is the primary field.