Codec Services

Codec Service

YDK CodecService class provides API for encoding and decoding of payload strings in XML or JSON format to/from instances of Entity, which represent containers in the device supported YANG models.

class ydk.services.CodecService

encode(provider, entity, pretty=True, subtree=False)

Encodes Entity into payload string in XML or JSON format.

Parameters

provider – CodecServiceProvider - Codec Provider instance.
entity – Entity instance or collection of Entity instances of type list or dict or EntityCollection.
pretty – bool flag, which specifies if resulting string must be in human readable way with indentation.
subtree – bool flag, which directs to encode entity to XML or JSON subtree. When set to true, the XmlSubtreeCodec or JsonSubtreeCodec is called accordingly.

Returns

Type of returned object corresponds to the type of entity: single payload str, or list of str, or a dictionary of str.

Raises

YServiceError, if error has occurred.

decode(provider, payload, subtree=False)

Decodes payload string in XML or JSON format to instances of Entity class.

Parameters

provider – CodecServiceProvider - Codec Provider instance.
payload – str or collection of str Either a single encoded payload or a collection of payloads encapsulated to list or dict.
subtree – bool flag, which directs to encode entity to XML or JSON subtree. When set to true, the XmlSubtreeCodec or JsonSubtreeCodec is called accordingly.

Returns

Type of returned object corresponds to the type of payload. It is either an instance of Entity, or a collection of Entity instances of type list or dict.

Raises

YServiceError, if error has occurred.

XmlSubtreeCodec

class ydk.entity_utils.XmlSubtreeCodec

XmlSubtreeCodec class designed to provide encoding and decoding Python model API objects of type Entity to/from XML encoded string. Compared to CodecService the class does not validate encoded data for their types and values. It is also can be used to encode/decode non-top level entities.

XmlSubtreeCodec(): Constructs an instance of XmlSubtreeCodec class.

encode(entity, root_schema)

Performs encoding of Python model API objects of type Entity to well formatted XML encoded string.

Parameters

entity – An instance of Entity class defined under a bundle.
root_schema – An instance of RootSchemaNode, which includes the model bundle.

Returns

str, encoded well formatted multi-line XML payload string.

Raises

YServiceError, if an error has occurred; usually appears when model is not present in the bundle.

decode(payload, entity)

Decodes the XML encoded string to produce corresponding instance of Entity.

Parameters

payload – str, XML encoded string to be decoded.
entity – Entity, instance of shared pointer to expected top level Entity class.

Returns

Entity, shared pointer to the decoded Entity.

Raises

YInvalidArgumentError, if an error has occurred; usually appears when payload does not correspond to Entity model.

JsonSubtreeCodec

class ydk.entity_utils.JsonSubtreeCodec

JsonSubtreeCodec class designed to provide encoding and decoding Python model API objects of type Entity to/from JSON encoded string. Compared to CodecService the class does not validate encoded data for their types and values. It is also can be used to encode/decode non-top level entities.

JsonSubtreeCodec(): Constructs an instance of JsonSubtreeCodec class.

encode(entity, root_schema, pretty)

Performs encoding of Python model API objects of type Entity to JSON encoded string.

Parameters

entity – An instance of Entity class defined under a bundle.
root_schema – An instance of RootSchemaNode, which includes the model bundle.
pretty – bool. If set to True, the function produces well formatted multi-line JSON string. If set to False - one line string.

Returns

str, encoded JSON payload string.

Raises

YServiceError, if an error has occurred; usually appears when model is not present in the bundle.

decode(payload, entity)

Decodes the JSON encoded string to produce corresponding instance of Entity.

Parameters

payload – str, JSON encoded string to be decoded.
entity – Entity, instance of shared pointer to expected top level Entity class.

Returns

Entity, shared pointer to the decoded Entity.

Raises

YInvalidArgumentError, if an error has occurred; usually appears when payload does not correspond to Entity model.

Example of JsonSubtreeCodec usage

In this example we use gNMIServiceProvider and CRUDService to get interface configuration from IOS XR device and then print it using JsonSubtreeCodec:

from ydk.services import CRUDService
from ydk.path import Repository
from ydk.gnmi.providers import gNMIServiceProvider

from ydk.models.cisco_ios_xr import Cisco_IOS_XR_ifmgr_cfg as ifmgr

# Create gNMI service provider
repo = Repository("/home/yan/ydk-gen/scripts/repository/10.30.110.84")
provider = gNMIServiceProvider(repo=repo,
                           address=10.20.30.40,
                           port=57400,
                           username='admin',
                           password='admin')
# Create CRUD service
crud = CRUDService()

# Build filter for interface configuration
ifc_filter = ifmgr.InterfaceConfigurations()
ifc = ifmgr.InterfaceConfigurations.InterfaceConfiguration()
ifc.active = '"act"'
ifc.interface_name = '"Loopback0"'
ifc_filter.interface_configuration.append(ifc)

# Read interface configuration
ifc_read = crud.read(provider, ifc_filter)

# Print interface configuration
if ifc_read:
    from ydk.entity_utils import JsonSubtreeCodec
    jcodec = JsonSubtreeCodec()
    payload = jcodec.encode(ifc_read, provider.get_session().get_root_schema(), True)
    print('CREATED INTERFACE CONFIGURATION:')
    print(payload)