Retrieving Objects From Nautobot¶
The Endpoint
class provides three methods
for retrieving Record
objects from Nautobot.
The
get()
method is used to get a single Record.The
filter()
method will return a list of Records.The
all()
method will return all Records for the Model.
Using the Get Method¶
The Retrieving Records sections shows how to use the
get()
method by passing in keyword arguments.
Another way to retrieve a Record is by passing in the value of the PK,
which is the ID for most objects.
>>> device = nautobot.dcim.devices.get('2302f2a1-2ed4-4ac9-a43a-285c95190071')
>>> device.name
'hq-access-01'
>>> device.status
Active
>>> device.device_type
c9300-48
>>> device.role
<pynautobot.core.response.Record ('Active') at ...>
Note
If an entry with the specified value for the PK does not exist,
then None
in the above example.
When using the get()
method
with keyword arguments, the keyword arguments must match only a single Record.
If multiple Records are matched, then a ValueError
is raised.
>>> device = nautobot.dcim.devices.get(device_type="c9300-48")
Traceback (most recent call last):
...
ValueError: get() returned more than one result.
Check that the kwarg(s) passed are valid for this endpoint
or use filter() or all() instead.
Using the Filter Method¶
The error message from the previous example suggests to use the
filter()
method.
Using this method will return a list of Record
instances; one for each matching record.
This method also supports:
filtering a single field with multiple values
filtering based on custom fields
filtering with lookup expressions
Basic Usage¶
The simplest usage of the filter()
method is to pass keyword arguments with single values.
The previous example raised an exception using the
get()
method,
but will return all matches using filter()
.
>>> # Get all c9300-48 devices
>>> devices = nautobot.dcim.devices.filter(device_type="c9300-48")
>>>
>>> # Show a list of Records are returned
>>> pprint(devices)
[<pynautobot.models.dcim.Devices ('hq-access-01') at ...>,
<pynautobot.models.dcim.Devices ('hq-access-02') at ...>,
<pynautobot.models.dcim.Devices ('hq-access-03') at ...>,
<pynautobot.models.dcim.Devices ('hq-access-04') at ...>]
>>>
>>> # Show accessing data from the first c9300-48 device
>>> device1 = devices[0]
>>> device1.name
'hq-access-01'
>>> device1.status
<pynautobot.core.response.Record ('Active') at ...>
Filtering with OR logic¶
The filter()
method allows
using an OR condition by passing in a list of values to match against the field.
The example below gets all devices located in either Location HQ
or DC
.
>>> # There are 100 devices total
>>> nautobot.dcim.devices.count()
100
>>>
>>> # There are 20 DC devices
>>> dev_dc_location = nautobot.dcim.devices.filter(location="DC")
>>> len(dev_dc_location)
20
>>>
>>> # There are 5 HQ devices
>>> dev_hq_location = nautobot.dcim.devices.filter(location="HQ")
>>> len(dev_hq_location)
5
>>>
# The filter method will grab all devices in both locations
>>> dev_hq_dc_locations = nautobot.dcim.devices.filter(location=["HQ", "DC"])
>>> len(dev_hq_dc_locations)
25
Filtering based on a Custom Field¶
Nautobot provides Custom Fields
as a way of extending a Model’s fields.
These fields can be referenced in the API by appending cf_ to the field’s name.
The below example has a custom field named owner, which is used to filter the devices
by passing the cf_owner
keyword argument.
>>> devices = nautobot.dcim.devices.filter(cf_owner="John Smith")
>>> devices
[<pynautobot.models.dcim.Devices ('switch0') at ...>,
<pynautobot.models.dcim.Devices ('switch1') at ...>]
>>>
>>> # Show device has an owner of "John Smith"
>>> devices[0].custom_fields["owner"]
'John Smith'
Filtering with Lookup Expressions¶
The Nautobot API uses Lookup Expressions to filter using something other than the exact matches that have been used so far. There are several expressions that can be used; they generally cover things like:
greater than
less than
not equal
starts with
contains
case insensitivity
The example below shows how use negation with __n.
From the previous examples, there are 100 devices total, and 25 are located in either the DC or HQ location.
Using location__n
to get the negation of these locations returns 75 devices.
>>> devices = nautobot.dcim.devices.filter(location__n=["HQ", "DC"])
>>> len(devices)
75
>>>
>>> # Show the device is not in either HQ or DC location
>>> devices[0].location
<pynautobot.core.response.Record ('branch1') at 0x7f650006df50>
Using the All Method¶
The all()
is used to get all records of a specific endpoint.
This will return a list of all Record
objects for the specific Endpoint.
>>> devices = nautobot.dcim.devices.all()
>>> len(devices)
100
>>> device1 = devices[0]
>>> device1.name
'hq-access-01'
>>> device1.status
Active
The following two pages cover interacting with the returned Record
objects.
The next page covers additional Update operations, which is followed by a discussion of other features and methods.