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@ekzemplaro(内田 雅智)

DynamoDB に boto3 で接続 （ハッシュキー、レンジキーを使う）

Last updated at Posted at 2018-02-13

次のページと同様ですが、ハッシュキーとレンジキーを使うサンプルです。
ハッシュ + レンジ　がプライマリーキーになります。

ローカルのDynamoDB に、python3 で CRUD を行う
参考にしたページ
Interfacing Amazon DynamoDB with Python using Boto3

このサンプルでは、ローカルの DynamoDB にアクセスします。

テーブルの作成
tbl_iot というテーブルを作成します。
ハッシュキー　は id_device
レンジキーは、 timestamp
です。

create_table.sh
#
aws dynamodb create-table --table-name 'tbl_iot' \
	--attribute-definitions \
		AttributeName=id_device,AttributeType=S \
		AttributeName=timestamp,AttributeType=S \
	--key-schema \
		AttributeName=id_device,KeyType=HASH \
		AttributeName=timestamp,KeyType=RANGE \
	--provisioned-throughput \
		ReadCapacityUnits=5,WriteCapacityUnits=5 \
	--endpoint-url http://localhost:8000
#

やり直す時のテーブルの削除

delete_table.sh
aws dynamodb delete-table --table-name tbl_iot --endpoint-url http://localhost:8000

テーブルの一覧を表示

list_table.sh
aws dynamodb list-tables --endpoint-url http://localhost:8000

データの挿入

insert_data.sh
#
#aws dynamodb list-tables --endpoint-url http://localhost:8000
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0001" }, "timestamp": { "S": "20180122082400" }, "temperature": { "N": "21.15" }, "humidity": { "N": "51.62" } }' \
	--endpoint-url http://localhost:8000
#
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0002" }, "timestamp": { "S": "20180122082100" }, "temperature": { "N": "22.25" }, "humidity": { "N": "50.51" } }' \
	--endpoint-url http://localhost:8000
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0002" }, "timestamp": { "S": "20180122082200" }, "temperature": { "N": "23.45" }, "humidity": { "N": "49.82" } }' \
	--endpoint-url http://localhost:8000
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0002" }, "timestamp": { "S": "20180122082300" }, "temperature": { "N": "24.55" }, "humidity": { "N": "53.15" } }' \
	--endpoint-url http://localhost:8000
#
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0003" }, "timestamp": { "S": "20180122082100" }, "temperature": { "N": "25.43" }, "humidity": { "N": "60.21" } }' \
	--endpoint-url http://localhost:8000
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0003" }, "timestamp": { "S": "20180122082200" }, "temperature": { "N": "27.25" }, "humidity": { "N": "59.42" } }' \
	--endpoint-url http://localhost:8000
#
aws dynamodb put-item --table-name tbl_iot --item \
	'{ "id_device": { "S": "ras0003" }, "timestamp": { "S": "20180122082300" }, "temperature": { "N": "26.15" }, "humidity": { "N": "61.26" } }' \
	--endpoint-url http://localhost:8000
#

ここからが、boto3 を使った python3 のプログラムです。

全てのデータを表示

scan01.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	scan01.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3

# --------------------------------------------------------------------
from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

response = table.scan()
display_proc(response['Items'])
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------
display.py
# -*- coding: utf-8 -*-
#
#	display.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys

# --------------------------------------------------------------------
def display_proc(items):
	for it in items:
		str_out = it['id_device'] + '\t'
		str_out += it['timestamp']  + '\t'
		str_out += str(it['temperature']) + '\t'
		str_out += str(it['humidity'])
		print(str_out)
#
# --------------------------------------------------------------------

実行結果
dynamodb_feb1301.png

特定のハッシュキーを持つものを表示
query を使用
この例では、ras0002 というキーのものを表示します。
同じことを scan を使ってもできます。(scan02.py)

query01.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	query01.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from boto3.dynamodb.conditions import Key

from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

id_in="ras0002"
sys.stderr.write ("id_in = " + id_in + "\n")
response = table.query(KeyConditionExpression=Key('id_device').eq(id_in))

display_proc(response['Items'])

sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

実行結果
dynamodb_feb1302.png

ハッシュキーと、レンジキーでひとつのデータを表示
get_item を使用

get_item01.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	get_item01.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from boto3.dynamodb.conditions import Key

from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

id_in="ras0002"
timestamp_in="20180122082300"
response = table.get_item(Key={'id_device': id_in,'timestamp': timestamp_in})
#
items=[response['Item']]
display_proc(items)
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

実行結果
dynamodb_feb1303.png

多くのデータを挿入する
batch_writer を使用

batch_write.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	batch_write.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from decimal import *

# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)
#
with table.batch_writer() as batch:
	min = 30
	for it in range(5):
		timestamp_aa = "2018012208" + str(min) + "00"
		tt = 20.5 + it / 10.0
		temperature = str(tt)
		hh = 31.4 + it / 5.0
		humidity = "%.2f" % hh
		batch.put_item(
			Item={
			'id_device': 'ras0002',
			'timestamp': timestamp_aa,
			'temperature': temperature,
			'humidity': humidity
			}
		)
		min += 1
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

scan を使ってハッシュキーが一致するものを表示
同じことを query を使ってもできます。(query01.py)

scan02.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	scan02.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from boto3.dynamodb.conditions import Key, Attr

# --------------------------------------------------------------------
from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

id_aa = 'ras0002'
sys.stderr.write ("id_aa = " + id_aa + "\n")

response = table.scan(
	FilterExpression=Attr('id_device').eq(id_aa)
	)

display_proc(response['Items'])
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

scan を使ってレンジキーが一致するものを表示

scan03.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	scan03.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from boto3.dynamodb.conditions import Key, Attr

# --------------------------------------------------------------------
from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

timestamp_aa = '20180122082300'
sys.stderr.write ("timestamp_aa = " + timestamp_aa + "\n")

response = table.scan(
	FilterExpression=Attr('timestamp').eq(timestamp_aa)
	)

display_proc(response['Items'])
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

scan を使って、レンジキーが条件を満たすものを表示
この場合は、timestamp がある時間より古いものを表示

scan04.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	scan03.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from boto3.dynamodb.conditions import Key, Attr

# --------------------------------------------------------------------
from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

timestamp_aa = '20180122082300'
sys.stderr.write ("timestamp_aa = " + timestamp_aa + "\n")
#
response = table.scan(
	FilterExpression=Attr('timestamp').lt(timestamp_aa)
	)

display_proc(response['Items'])
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

scan を使って、ハッシュキーが一致して、かつレンジキーが条件を満たすものを表示
この場合は、ras0002 で、timestamp がある時間より古いものを表示

scan05.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	scan05.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from boto3.dynamodb.conditions import Key, Attr

# --------------------------------------------------------------------
from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
table = dynamodb.Table(table_name)

id_aa = 'ras0002'
timestamp_aa = '20180122082300'
sys.stderr.write ("id_aa = " + id_aa + "\n")
sys.stderr.write ("timestamp_aa = " + timestamp_aa + "\n")
#
response = table.scan(
	FilterExpression= Attr('id_device').eq(id_aa) & Attr('timestamp').lt(timestamp_aa))

#
display_proc(response['Items'])
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

batch_get_item　の使い方

batch_get_item.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	batch_get_item.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
# --------------------------------------------------------------------
from display import display_proc
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")

table_name = 'tbl_iot'
#
response = dynamodb.batch_get_item(
	RequestItems={
		table_name: {
			'Keys': [
			{'id_device':'ras0002', 'timestamp':"20180122082200"},
			{'id_device':'ras0002', 'timestamp':"20180122082300"},
			{'id_device':'ras0003', 'timestamp':"20180122082300"}
				]
			}
	})
#
display_proc(response['Responses'][table_name])
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------

ハッシュキーが一致して、かつレンジキーが条件を満たすものを削除
この場合は、ras0002 で、timestamp がある時間より古いものを削除
batch_writer()　を使用

batch_delete.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	batch_delete.py
#
#					Feb/13/2018
# --------------------------------------------------------------------
import	sys
import	boto3
from decimal import *
from boto3.dynamodb.conditions import Key, Attr
# --------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")

table_name = 'tbl_iot'
id_aa = 'ras0002'
timestamp_aa = '20180122082300'
sys.stderr.write ("id_aa = " + id_aa + "\n")
sys.stderr.write ("timestamp_aa = " + timestamp_aa + "\n")

dynamodb = boto3.resource('dynamodb',endpoint_url="http://localhost:8000")
client = boto3.client('dynamodb',endpoint_url="http://localhost:8000")
response = client.describe_table(TableName=table_name)
keys = [k['AttributeName'] for k in response['Table']['KeySchema']]
print(keys)

table = dynamodb.Table(table_name)
response = table.scan(
	FilterExpression= Attr('id_device').eq(id_aa) & Attr('timestamp').lt(timestamp_aa))

items = response['Items']
#
with table.batch_writer() as batch:
	for item in items:
		key_dict = {k: item[k] for k in keys}
		print("Deleting " + str(item) + "...")
		print(key_dict)
		batch.delete_item(Key=key_dict)
#
sys.stderr.write("*** 終了 ***\n")
# --------------------------------------------------------------------
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