How to authorize users to access GSI

Question

How do I authorizer all users to access a GSI? (In my case, the userIndex)

I can access the primary-index just fine. I successfully authorized all users to access the primary-index the following way:

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Here I target the primary-index, which works just fine

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Here I target the GSI, which doesn't work:

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I tried adding dynamodb to my AuthStack at the two places you can see in the image below (to no avail). I doubt changing the AuthStack will do anything, since it is a lambda function that is making the Put request to DynamoDb (I might be wrong though).

Answer 1

I figured it out.

First of all, you are not supposed to write to a gsi, only read.

Secondly, when wantin gto query a gsi, you have to specify the TableName together with IndexName.

The following works