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)