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e01_ngsi_v2_context_basics.py
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e01_ngsi_v2_context_basics.py
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"""
# Example how to use Entity-models and interact with the Orion ContextBroker
"""
# ## Import packages
import logging
from filip.clients.ngsi_v2 import ContextBrokerClient
from filip.models.base import FiwareHeader, DataType
from filip.models.ngsi_v2.context import ContextEntity, ContextAttribute, \
NamedContextAttribute
from filip.utils.simple_ql import QueryString
from filip.config import settings
# ## Parameters
#
# To run this example, you need a working Fiware v2 setup with a context-broker
# You can set the address here:
#
# Host address of Context Broker
CB_URL = settings.CB_URL
# You can also change the used Fiware service
# FIWARE-Service
SERVICE = 'filip'
# FIWARE-Service path
SERVICE_PATH = '/example'
# Setting up logging
logging.basicConfig(
level='INFO',
format='%(asctime)s %(name)s %(levelname)s: %(message)s',
datefmt='%d-%m-%Y %H:%M:%S')
logger = logging.getLogger(__name__)
if __name__ == "__main__":
# # 1 Setup Client
#
# create the client, for more details view the example: e01_http_clients.py
fiware_header = FiwareHeader(service=SERVICE,
service_path=SERVICE_PATH)
cb_client = ContextBrokerClient(url=CB_URL,
fiware_header=fiware_header)
# View version
for key, value in cb_client.get_version().items():
logger.info(f"Context broker version: {value['version']} at url: "
f"{cb_client.base_url}")
# # 2 Create Entities
#
# ## 2.1 Build Models
#
# Entities can be created by:
#
# ### 2.1.1 Passing a dict:
#
room1_dictionary = {"id": "urn:ngsi-ld:Room:001",
"type": "Room",
"temperature": {"value": 11,
"type": "Float"},
"pressure": {"value": 111,
"type": "Integer"}
}
room1_entity = ContextEntity(**room1_dictionary)
# ### 2.1.2 Using the constructor and interfaces
#
room2_entity = ContextEntity(id="urn:ngsi-ld:Room:002", type="Room")
temp_attr = NamedContextAttribute(name="temperature", value=22,
type=DataType.FLOAT)
pressure_attr = NamedContextAttribute(name="pressure", value=222,
type="Integer")
room2_entity.add_attributes([temp_attr, pressure_attr])
# ## 2.2 Post Entities
#
logger.info(f'Entity list before posting to CB: {cb_client.get_entity_list()}')
cb_client.post_entity(entity=room1_entity)
cb_client.post_entity(entity=room2_entity)
# # 3 Access entities in Fiware
#
# Get all entities from context broker
logger.info(f'Entity list after posting to CB: {cb_client.get_entity_list()}')
# Get entities by id
logger.info(f'Entities with ID "urn:ngsi-ld:Room:001": '
f'{cb_client.get_entity_list(entity_ids=["urn:ngsi-ld:Room:001"])}')
# Get entities by type
logger.info(f'Entities by type "Room": {cb_client.get_entity_list(entity_types=["Room"])}')
# Get entities by id pattern
# The regular expression filters the rooms that have the id number 2 through 5
# with the prefix 'urn:ngsi-ld:Room:'
logger.info(f'Entities with id pattern "^urn:ngsi-ld:Room:00[2-5]": '
f'{cb_client.get_entity_list(id_pattern="^urn:ngsi-ld:Room:00[2-5]")}')
# Get entities by query expression
query = QueryString(qs=[('temperature', '>=', 22)])
logger.info(f'Entities with temperature >= 22: {cb_client.get_entity_list(q=query)}')
# Get attributes of entities
logger.info(f'Attributes of entities: {cb_client.get_entity_attributes(entity_id="urn:ngsi-ld:Room:001")}')
# Trying to access non-existing ids or attributes will always throw
# a request error
# # 4 Changing Entities
#
# ## 4.1 Updating
entity = room2_entity
entity.add_attributes({'Space': ContextAttribute(type='Number',
value=111)})
# ### 4.1.1 Updating directly
#
# Using the Filip interface, we can update different properties of our
# entity directly in the live version in FIWARE. A few examples of what
# is possible are listed here:
# Updating value of an attribute of an entity
logger.info(cb_client.update_attribute_value(entity_id=room1_entity.id,
attr_name="temperature",
value=12))
# Deleting attributes
# logger.info(cb_client.delete_entity_attribute(entity_id=room1_entity.id,
# attr_name="temperature"))
# ### 4.1.2 Updating the model
#
# Most of the time it is more convenient to update our local model,
# and let the library handle all the needed updates to synchronise the
# live state to the model state.
# Hereby it is tried to only make changes that were done locally,
# keeping as much of the current live state as possible
# When accessing an attribute a new object is created. We need to
# manually transmit the made changes.
temp_attr = room2_entity.get_attribute("temperature")
temp_attr.value = 15
room2_entity.update_attribute([temp_attr])
room2_entity.delete_attributes(["pressure"])
# all changes are transmitted with one methode call
cb_client.patch_entity(room2_entity)
# ## 4.2 Deleting
#
# To delete an entry in Fiware, we can call:
cb_client.delete_entity(entity_id=room2_entity.id,
entity_type=room2_entity.type)
cb_client.delete_entity(entity_id=room1_entity.id,
entity_type=room1_entity.type)