Reputation: 23
looking for an answer to this question if possible, not looking for a refactoring advice or redesign, i just need to understand what else I am missing here :
I have an existing item in dynamodb:
{
"CartId": 321,
"UserId": usr555,
"CartItems": [
{
"ProductId":59999,
"Quantity": 1
},
{
"ProductId": 58888,
"Quantity": 2
}
]
}
in my code I want to insert another nested attribute into the array CartItems in the item above. i can't find a way of doing this without retrieving the entire item and then inserting, which could amount to KBs in size.
all I want to do is insert a single array element in an existing nested attribute without having to retrieve the item.
the language I am using is nodejs and the function is DynamoDB.put.
Upvotes: 2
Views: 1079
Reputation: 6333
UpdateExpression attribute supports SET action and SET action supports list_append function. Since list_append function operands must be list, enclose the new value within a list as below.
response = dynamodb_client.update_item(TableName='your_table',
Key={'CartId':'321'},
UpdateExpression='SET CartItems = list_append(CartItems, :val1)',
ExpressionAttributeValues = {':val1':[{'ProductId':12345, 'Quantity': 100}]})
Hope this helps
Upvotes: 2