Dynamodb Update Item Expression with python boto3

Question

I have a string field, "title". I am trying to update it with the update expression with

persontable.update_item(Key={'person_id':person_id}, UpdateExpression="SET title = UPDATED")

and I get

An error occurred (ValidationException) when calling the UpdateItem operation: The provided expression refers to an attribute that does not exist in the item

I can see the attribute "title" for that person in the AWS console. What gives?

This question solved it for me: stackoverflow.com/questions/30586608/… — George B
– George B, Commented Jan 9, 2016 at 5:13

user254873 · Accepted Answer · 2016-05-31 09:48:02Z

14

Don't plug the value into the expression directly. Rather use ExpressionAttributeValues -- see boto3 guide

persontable.update_item(Key={'person_id':person_id},
                        UpdateExpression="SET title = :updated",                   
                        ExpressionAttributeValues={':updated': 'UPDATED'})

edited May 31, 2016 at 9:48

answered May 31, 2016 at 9:19

user254873

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3 Comments

Willie Cheng Over a year ago

Please check this URL it will be useful to raise your content quality up

FreyGeospatial Over a year ago

This answer solved my problem, where I was previously attempting to plug the value into the expression directly and my code errored out. Thank you!

Mike B Over a year ago

why does AWS make this so complicated? i.e., why do we write out an arbitrary string that AWS CLI parses? seems like an overly complicated approach

Chandra Sekhar K · Accepted Answer · 2018-09-11 12:51:51Z

-1

Check whether item has created properly before updating.

When the Table is not in "ACTIVE" state, if you try to put_item - it will not be created and next when when you try to update the same item which is not created. This error will occur.

Execute the put_item when the state is in "ACTIVE" state and then update item properly. You will not get this error.

answered Sep 11, 2018 at 12:51

Chandra Sekhar K

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