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# coding: utf-8
# -------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for
# license information.
# --------------------------------------------------------------------------
"""
FILE: sample_conditional_update.py
DESCRIPTION:
These samples demonstrate how to update Tables storage table conditionally. The way to update Tables cosmos table is similar.
USAGE:
python sample_conditional_update.py
Set the environment variables with your own values before running the sample:
1) TABLES_STORAGE_ENDPOINT_SUFFIX - the Table storage service account URL suffix
2) TABLES_STORAGE_ACCOUNT_NAME - the Tables storage account name
3) TABLES_PRIMARY_STORAGE_ACCOUNT_KEY - the Tables storage account access key
"""
import os
from datetime import datetime
from dotenv import find_dotenv, load_dotenv
from uuid import uuid4, UUID
from azure.data.tables import TableClient
from azure.data.tables._models import UpdateMode
from azure.core import MatchConditions
from azure.core.exceptions import ResourceExistsError, ResourceModifiedError
from typing_extensions import TypedDict
class EntityType(TypedDict, total=False):
PartitionKey: str
RowKey: str
text: str
color: str
price: float
last_updated: datetime
product_id: UUID
inventory_count: int
barcode: bytes
class ConditionalUpdateSamples(object):
def __init__(self):
load_dotenv(find_dotenv())
self.access_key = os.environ["TABLES_PRIMARY_STORAGE_ACCOUNT_KEY"]
self.endpoint_suffix = os.environ["TABLES_STORAGE_ENDPOINT_SUFFIX"]
self.account_name = os.environ["TABLES_STORAGE_ACCOUNT_NAME"]
self.endpoint = f"{self.account_name}.table.{self.endpoint_suffix}"
self.connection_string = f"DefaultEndpointsProtocol=https;AccountName={self.account_name};AccountKey={self.access_key};EndpointSuffix={self.endpoint_suffix}"
self.table_name_prefix = "SampleConditionalUpdate"
self.entity1: EntityType = {
"PartitionKey": "color",
"RowKey": "brand",
"text": "Marker",
"color": "Purple",
"price": 4.99,
"last_updated": datetime.today(),
"product_id": uuid4(),
}
self.entity2: EntityType = {
"PartitionKey": "color",
"RowKey": "brand",
"color": "Red",
"inventory_count": 42,
"barcode": b"135aefg8oj0ld58", # cspell:disable-line
}
def conditional_update_basic(self):
with TableClient.from_connection_string(
self.connection_string, self.table_name_prefix + uuid4().hex
) as table_client:
table_client.create_table()
metadata1 = table_client.create_entity(entity=self.entity1)
print("Entity:")
print(self.entity1)
# Merge properties of an entity with one that already existed in a table.
# This operation will only succeed if the entity has not been modified since we last retrieved the Etag.
try:
metadata2 = table_client.update_entity(
entity=self.entity2,
mode=UpdateMode.MERGE,
match_condition=MatchConditions.IfNotModified,
etag=metadata1["etag"],
)
except ResourceModifiedError:
print("This entity has been altered and may no longer be in the expected state.")
entity2 = table_client.get_entity(
partition_key=self.entity1["PartitionKey"], row_key=self.entity1["RowKey"]
)
print("Entity after merge:")
print(entity2)
# Update an existing entity by replacing all of its properties with those specified.
# This operation will only succeed if the entity has not been modified since we last retrieved the Etag.
try:
table_client.update_entity(
entity=self.entity2,
mode=UpdateMode.REPLACE,
match_condition=MatchConditions.IfNotModified,
etag=metadata2["etag"],
)
except ResourceModifiedError:
print("This entity has been altered and may no longer be in the expected state.")
entity3 = table_client.get_entity(
partition_key=self.entity1["PartitionKey"], row_key=self.entity1["RowKey"]
)
print("Entity after replace:")
print(entity3)
table_client.delete_table()
def conditional_update_with_a_target_field(self):
with TableClient.from_connection_string(
self.connection_string, self.table_name_prefix + uuid4().hex
) as table_client:
table_client.create_table()
table_client.create_entity(entity=self.entity1)
target_field = "barcode"
# In this scenario, will try to create an entity at first. If the entity with the same PartitionKey and RowKey already exists,
# will update the existing entity when target field is missing.
try:
table_client.create_entity(entity=self.entity2)
except ResourceExistsError:
entity = table_client.get_entity(
partition_key=self.entity2["PartitionKey"], row_key=self.entity2["RowKey"]
)
if target_field not in entity:
table_client.update_entity(
entity={
"PartitionKey": self.entity2["PartitionKey"],
"RowKey": self.entity2["RowKey"],
target_field: "foo",
},
mode=UpdateMode.MERGE,
match_condition=MatchConditions.IfNotModified,
etag=entity.metadata["etag"],
)
table_client.delete_table()
if __name__ == "__main__":
sample = ConditionalUpdateSamples()
sample.conditional_update_basic()
sample.conditional_update_with_a_target_field()
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