Query DynamoDB with multiple begins_with clause in AppSync

I'm currently trying to create a dynamic query using AppSync and Apache Velocity Template Language (VTL).

I want to evaluate series of begins_with with "OR"

Such as:

{
    "operation": "Query",
    "query": {
        "expression": "pk = :pk and (begins_with(sk,:sk) or begins_with(sk, :sk1)",
        "expressionValues": {
      ":pk": { "S": "tenant:${context.args.tenantId}",
      ":sk": {"S": "my-sort-key-${context.args.evidenceId[0]}"},
      ":sk1": {"S": "my-sort-key-${context.args.evidenceId[1]}"}

   }

    }

But that isn't working. I've also tried using | instead of or but it hasn't worked either. I get:

Invalid KeyConditionExpression: Syntax error; token: "|", near: ") | begins_with" (Service: AmazonDynamoDBv2;

How can I achieve this using VTL?

Original answer

you're missing a closing parenthesis after the begins_with(sk, :sk1). That is, the third line should be:

        "expression": "pk = :pk and (begins_with(sk,:sk) or begins_with(sk, :sk1))"

I just ran the fixed expression and it worked as expected.

Revised

Actually, there are subtleties.

the or operator can be used in filter-expression but not in key-condition-expressions. For instance, a = :v1 and (b = :v2 or b = :v3) will work as long as a and b are "regular" attributes. If a and b are the table's primary key (partition key, sort key) then DDB will reject the query.