I have an existing DynamoDB table, and I want to write some Python code to append an attribute (of type List) to the table. Here is what I tried:
users.put_item(
Item={
"new_attribute": []
}
)
But this didn't work. I looked everywhere online but couldn't find anything, I know I must be missing something basic. Any help?
Here is a full example which works
### Simulating an Insert and Update to a List
#Create Table
import boto3
dynamodb = boto3.resource('dynamodb')
try:
table = dynamodb.create_table(
TableName='Test_list',
KeySchema=[
{
'AttributeName': '_id',
'KeyType': 'HASH' # Partition key
}
],
AttributeDefinitions=[
{
'AttributeName': '_id',
'AttributeType': 'N'
}
],
ProvisionedThroughput={
'ReadCapacityUnits': 5,
'WriteCapacityUnits': 5
}
)
except ClientError as e:
if e.response['Error']['Code']:
print(e.response['Error']['Message'])
print( e.response)
## Add a record with a list
table= dynamodb.Table('Test_list')
ll=['one','two']
resp=table.put_item(
Item={
'_id': 1,
'mylist': ll
}
)
#Update the list
new_ll=['three','four']
response = table.update_item(
Key={
'_id': 1
},
UpdateExpression="SET #l = list_append(#l, :vals)",
ExpressionAttributeNames={
"#l": 'mylist'
},
ExpressionAttributeValues={
":vals": new_ll
}
)
# fetch the record to verify
resp=table.get_item(Key={'_id':1})
resp['Item']
You will see the output :
{'_id': Decimal('1'), 'mylist': ['one', 'two', 'three', 'four']}
import boto3
dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('<your-ddb-table-name>')
table.update_item(
Key={
'PK': '<pk>',
'SK': '<sk>'
},
UpdateExpression='SET new_attribute = :list',
ExpressionAttributeValues={
':list': []
}
)
botocore.exceptions.ClientError: An error occurred (ValidationException) when calling the UpdateItem operation: The provided key element does not match the schema