根據(jù)我的代碼，首先，我向地圖添加一個(gè)新字典，它會(huì)成功更新到我的地圖。但是，當(dāng)我向地圖添加另一個(gè)字典時(shí)，地圖中的現(xiàn)有鍵會(huì)被覆蓋。def update_item(table_name, id, new_company): table = dynamodb.Table(table_name) result = table.update_item( Key={ 'id': id }, UpdateExpression="SET company = :company", ExpressionAttributeValues={ ':company': new_company }, ReturnValues="ALL_NEW" ) print(result)if __name__ == '__main__': company_1 = { "Facebook" : { "CEO" : "Mark" } } update_item('companies', 1, company_1) company_2 = { "Twitter": { "CEO": "Jack" } } update_item('companies', 1, company_2)我的輸出：我的 Dynamodb 表中可用的項(xiàng)目{ 'company': { 'Twitter': { 'CEO': 'Jack' } }, 'id': Decimal('1'), 'industry': 'industry'}預(yù)期輸出：{ 'company': { 'Facebook': { 'CEO': 'Mark' } 'Twitter': { 'CEO': 'Jack' } }, 'id': Decimal('1'), 'industry': 'industry'}當(dāng)我向地圖添加新字典時(shí)，如何避免覆蓋現(xiàn)有字典？我是 DynamoDB 的新手，任何建議都會(huì)有幫助。
2 回答
阿晨1998
TA貢獻(xiàn)2037條經(jīng)驗(yàn) 獲得超6個(gè)贊
問題出在你的UpdateExpression.?您每次都將 map 的值設(shè)置company為新值：
SET??company?=?:company
但聽起來您想向地圖附加一個(gè)新值company。
慕姐8265434
TA貢獻(xiàn)1813條經(jīng)驗(yàn) 獲得超2個(gè)贊
我是 Lucid-Dynamodb 的作者，它是 AWS DynamoDB 的極簡包裝器。使用我的庫可以輕松解決這個(gè)問題。
參考： https: //github.com/dineshsonachalam/Lucid-Dynamodb
from LucidDynamodb.Operations import DynamoDb
import os
import logging
logging.basicConfig(level=logging.INFO)
AWS_ACCESS_KEY_ID = os.getenv("AWS_ACCESS_KEY_ID")
AWS_SECRET_ACCESS_KEY = os.getenv("AWS_SECRET_ACCESS_KEY")
table_schema = {
"TableName": "company",
"KeySchema": [
{
"AttributeName": "id",
"KeyType": "HASH"
}
],
"AttributeDefinitions": [
{
"AttributeName": "id",
"AttributeType": "N"
}
],
"GlobalSecondaryIndexes": [],
"ProvisionedThroughput": {
"ReadCapacityUnits": 1,
"WriteCapacityUnits": 1
}
}
if __name__ == "__main__":
# 1. create a new table
db = DynamoDb(region_name="us-east-1",
aws_access_key_id=AWS_ACCESS_KEY_ID,
aws_secret_access_key=AWS_SECRET_ACCESS_KEY)
table_creation_status = db.create_table(
TableName=table_schema.get("TableName"),
KeySchema=table_schema.get("KeySchema"),
AttributeDefinitions=table_schema.get("AttributeDefinitions"),
GlobalSecondaryIndexes=table_schema.get("GlobalSecondaryIndexes"),
ProvisionedThroughput=table_schema.get("ProvisionedThroughput")
)
if(table_creation_status == True):
logging.info("{} table created successfully".format(table_schema.get("TableName")))
else:
logging.error("{} table creation failed".format(table_schema.get("TableName")))
# 2. Create a new item
item_creation_status = db.create_item(
TableName=table_schema.get("TableName"),
Item= {
'company': {
'Facebook': {
'CEO': 'Mark'
}
},
'id': 1,
'industry': 'internet'
}
)
if(item_creation_status == True):
logging.info("Item created successfully")
else:
logging.warning("Item creation failed")
# 3. Add a new attribute in a item
item_update_status = db.update_item(
TableName=table_schema.get("TableName"),
Key={
'id': 1
},
AttributesToUpdate={
'company.Twitter': {
'CEO': 'Jack'
}
}
)
if(item_update_status == True):
logging.info("Update is successful")
else:
logging.warning("Update failed")
item = db.read_item(
TableName=table_schema.get("TableName"),
Key={
'id': 1
})
if(item != None):
logging.info("Item: {}".format(item))
else:
logging.warning("Item doesn't exist")
輸出：
dineshsonachalam@macbook Dynamodb-experiment % python test.py
INFO:root:company table created successfully
INFO:root:Item created successfully
INFO:root:Update is successful
INFO:root:Item:
{
'company': {
'Facebook': {
'CEO': 'Mark'
},
'Twitter': {
'CEO': 'Jack'
}
},
'id': Decimal('1'),
'industry': 'internet'
}
紅顏莎娜
TA貢獻(xiàn)1842條經(jīng)驗(yàn) 獲得超13個(gè)贊
您只需在#name 處添加一個(gè)地圖條目即可。
def update_item(table_name, id, new_company):
table = dynamodb.Table(table_name)
name = list(new_company)[0]
result = table.update_item(
Key={
'id': id
},
UpdateExpression="SET company.#name = :company",
ExpressionAttributeNames={"#name": name},
ExpressionAttributeValues={
':company': new_company[name]
},
ReturnValues="ALL_NEW"
)
print(result)
輸出：我的 Dynamodb 中可用的項(xiàng)目
{
'company': {
'Facebook': {
'CEO': 'Mark'
},
'Twitter': {
'CEO': 'Jack'
}
},
'id': Decimal('1'),
'industry': 'internet'
}
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