How do I create, update, read and delete?

This document contains some examples of creating, reading and deleting yang data using YDK. To perform these operations, the CRUDService is used. Also, in these examples, YFilter is used to mark parts of the data for particular operations.

Creating a configuration with a list and a presence class 

To configure a rule in the SNMP trap correlator, the below approach can be used.

Note that the Cisco_IOS_XR_snmp_agent_cfg.Snmp.Correlator.Rules.Rule class is a YList. So it needs to be instantiated and appended to its parent.

Also, the attribute non_stateful is an instance of a presence class, which is set to None by default. So it needs to be assigned to a new instance of its class.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_snmp_agent_cfg

# Create the top-level container
snmp = Cisco_IOS_XR_snmp_agent_cfg.Snmp()

# Create the list instance
rule = Cisco_IOS_XR_snmp_agent_cfg.Snmp.Correlator.Rules.Rule()
rule.name = 'abc'

# Instantiate and assign the presence class
rule.non_stateful = Cisco_IOS_XR_snmp_agent_cfg.Snmp.Correlator.Rules.Rule.NonStateful()

rule.non_stateful.timeout = 3

# Append the list instance to its parent
snmp.correlator.rules.rule.append(rule)

# Call the CRUD create on the top-level snmp object
# (assuming you have already instantiated the service and provider)
result = crud.create(provider, snmp)

Creating and replacing a configuration 

First, let us create a configuration for the openconfig_bgp.Bgp.Global_.Config class. Here, we set the leaf as_, which represents the autonomous system number, to 65001 and the leaf router_id to '10.0.0.1'.

from ydk.types import YFilter
from ydk.models.openconfig import openconfig_bgp

# First, create the top-level Bgp() object
bgp = openconfig_bgp.Bgp()

# Populate the values for the global config object
bgp.global_.config.as_ = 65001
bgp.global_.config.router_id = '10.0.0.1'

# Call the CRUD create on the top-level bgp object
# (assuming you have already instantiated the service and provider)
result = crud.create(provider, bgp)

Now, let us replace the above configuration with a new configuration for the openconfig_bgp.Bgp.Global_.Config class using the below code.

from ydk.types import YFilter
from ydk.models.openconfig import openconfig_bgp

# First, create the top-level Bgp() object
bgp = openconfig_bgp.Bgp()

# Set the yfilter attribute of the config object to YFilter.replace
bgp.global_.config.yfilter = YFilter.replace

# Populate the new values for the global config object
bgp.global_.config.as_ = 65023
bgp.global_.config.router_id = '25.3.55.12'

# Call the CRUD update on the top-level bgp object
# (assuming you have already instantiated the service and provider)
result = crud.update(provider, bgp)

Creating and reading a list 

For example, to read the instances of a deeply nested YList called Cisco_IOS_XR_ip_rib_ipv4_oper.Rib.Vrfs.Vrf.Afs.Af.Safs.Saf.IpRibRouteTableNames.IpRibRouteTableName.Routes.Route in the Cisco_IOS_XR_ip_rib_ipv4_oper module using YDK’s CRUDService, the below approach can be used.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_ip_rib_ipv4_oper
from ydk.filters import YFilter

# First create the top-level Rib() object
rib = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib()

# Then create the list instance Vrf()
vrf = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib.Vrfs.Vrf()
vrf.vrf_name='default'

# Then create the child list element Af() and the rest of the nested list instances
af = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib.Vrfs.Vrf.Afs.Af()
af.af_name = 'IPv4'

saf = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib.Vrfs.Vrf.Afs.Af.Safs.Saf()
saf.saf_name='Unicast'

table_name = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib.Vrfs.Vrf.Afs.Af.Safs.Saf.IpRibRouteTableNames.IpRibRouteTableName()
table_name.route_table_name = 'default'

# Create the final list instance Route()
route = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib.Vrfs.Vrf.Afs.Af.Safs.Saf.IpRibRouteTableNames.IpRibRouteTableName.Routes.Route()
route.yfilter = YFilter.read # set the yfilter attribute for route to YFilter.read

# Append each of the list instances to their respective parents
table_name.routes.route.append(route)
saf.ip_rib_route_table_names.ip_rib_route_table_name.append(table_name)
af.safs.saf.append(saf)
vrf.afs.af.append(af)
rib.vrfs.vrf.append(vrf)

# Call the CRUD read on the top-level rib object
# (assuming you have already instantiated the service and provider)
rib_oper = crud.read(provider, rib)

vrf_list = rib_oper.vrfs.vrf
vrf_default = vrf_list["default"]  # or  vrf_default = vrf_list.get("default")

Read all VRF configuration:

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_ip_rib_ipv4_oper
from ydk.filters import YFilter

# First create the top-level Rib() object
rib = Cisco_IOS_XR_ip_rib_ipv4_oper.Rib()

# Call the CRUD read on the top-level rib object
# (assuming you have already instantiated the service and provider)
rib_oper = crud.read(provider, rib)

# Access all VRFs in the list
for vrf in rib_oper.vrfs.vrf:
    print(vrf.vrf_name)

# Get list of VRF names
all_vrf_names = rib_oper.vrfs.vrf.keys()

# Iterate over VRF names
for vrf_name in all_vrf_names:
    vrf = rib_oper.vrfs.vrf[vrf_name]
    for af in vrf.afs.af:
        print("VRF: %s, AF: %s", vrf_name, af)

# Access specific VRF, when name is known
vrf = rib_oper.vrfs.vrf["default"]
if vrf is not None:
    for af in vrf.afs.af:
        print("VRF: %s, AF: %s", "default", af)

Reading a leaf 

For example, to read a YLeaf called running in the Cisco_IOS_XR_clns_isis_cfg.Isis.Instances.Instance class in the Cisco_IOS_XR_clns_isis_cfg module using YDK’s CRUDService, the below approach can be used.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_clns_isis_cfg
from ydk.types import Empty
from ydk.filters import YFilter

# First create the top-level Isis() object
isis = Cisco_IOS_XR_clns_isis_cfg.Isis()

# Create the list instance
ins = Cisco_IOS_XR_clns_isis_cfg.Isis.Instances.Instance()
ins.instance_name = 'default'

# Set the yfilter attribute of the leaf called 'running' to YFilter.read
ins.running = YFilter.read

# Append the instance to the parent
isis.instances.instance.append(ins)

# Call the CRUD read on the top-level isis object
# (assuming you have already instantiated the service and provider)
result = crud.read(provider, isis)

Deleting a list element 

For example, to delete a YList called Instance in the Cisco_IOS_XR_clns_isis_cfg module using YDK’s CRUDService, the below approach can be used.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_clns_isis_cfg
from ydk.types import Empty
from ydk.filters import YFilter

# First create the top-level Isis() object
isis = Cisco_IOS_XR_clns_isis_cfg.Isis()

# Create the list instance
ins = Cisco_IOS_XR_clns_isis_cfg.Isis.Instances.Instance()
ins.instance_name = 'xyz'

# Set the yfilter attribute of the leaf called 'running' to YFilter.delete
ins.yfilter = YFilter.delete

# Append the instance to the parent
isis.instances.instance.append(ins)

# Call the CRUD update on the top-level isis object
# (assuming you have already instantiated the service and provider)
result = crud.update(provider, isis)

Deleting entire list 

In order to delete entire list, all its elements must be deleted. It could be done like in example above. The issue here is that user have to know all the keys of the YList elements. To address this issue YDK offers a shortcut, which allows user to delete all list elements in one operation.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_clns_isis_cfg
from ydk.filters import YFilter

# First read configuration of top level container
isis = crud.read_config(provider, Cisco_IOS_XR_clns_isis_cfg.Isis()

# Then set YFilter.delete operation to the YList object
if len(isis.instances.instance) > 0:
    isis.instances.instance.yfilter = YFilter.delete

    # Call the CRUD update on modified 'isis' object
    result = crud.update(provider, isis)

Deleting a leaf 

For example, to delete a YLeaf called timer of type int in the Cdp class in the Cisco_IOS_XR_cdp_cfg module using YDK’s CRUDService, the below approach can be used.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_cdp_cfg
from ydk.filters import YFilter

# First create the top-level Cdp() object
cdp = Cisco_IOS_XR_cdp_cfg.Cdp()

# Set a dummy value to the leaf
cdp.timer = 5
# Assign YFilter.delete to the 'timer' leaf
cdp.timer = YFilter.delete

# Call the CRUD update on the top-level cdp object
# (assuming you have already instantiated the service and provider)
result = crud.update(provider, cdp)

For example, to delete a YLeaf called running of type Empty in the Instance class in the Cisco_IOS_XR_clns_isis_cfg module using YDK’s CRUDService, the below approach can be used.

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_clns_isis_cfg
from ydk.types import Empty
from ydk.filters import YFilter

# First create the top-level Isis() object
isis = Cisco_IOS_XR_clns_isis_cfg.Isis()

# Create the list instance
ins = Cisco_IOS_XR_clns_isis_cfg.Isis.Instances.Instance()
ins.instance_name = 'default'

# Assign YFilter.delete to the 'running' leaf
ins.running = YFilter.delete

# Append the instance to the parent
isis.instances.instance.append(ins)

# Call the CRUD update on the top-level isis object
# (assuming you have already instantiated the service and provider)
result = crud.update(provider, isis)

Applying CRUD to multiple entities 

You can apply CRUD operations on multiple entities in one CRUD service call. For example, you want to ‘read’ BGP and Interfaces configuration together.

from ydk.types import Filter, Config
from ydk.models.openconfig import openconfig_bgp, openconfig_interfaces

# First, create the top-level Bgp and Interface objects
int_filter = openconfig_interfaces.Interfaces()
bgp_filter = openconfig_bgp.Bgp()

# Create read filter
read_filter = Filter(int_filter, bgp_filter)

# Call the CRUD read-config to get configuration of entities
result = crud.read_config(provider, read_filter)

# Access read results from returned Config collection
int_config = result[int_filter]
bgp_config = result[bgp_filter]

# Or print all configuration in XML format
codec_service = CodecService()
codec_provider = CodecServiceProvider()
codec_provider.encoding = EncodingFormat.XML
for entity in result:
    xml_encode = codec_service.encode(codec_provider, entity)
    print(xml_encode)