Part of structured approach for UpdateExpressions:
1) Expression gets parsed into a tokenlist (tokenized)
2) Tokenlist get transformed to expression tree (AST)
3) The AST gets validated (full semantic correctness)
4) AST gets processed to perform the update -> this commit
This commit uses the AST to execute the UpdateExpression.
All the existing tests pass. The only tests that have been
updated are in test_dynamodb_table_with_range_key.py because
they wrongly allow adding a set to a path that doesn't exist.
This has been alligend to correspond to the behavior of AWS
DynamoDB.
This commit will resolve https://github.com/spulec/moto/issues/2806
Multiple tests have been implemented that verify this.
This commit puts AST validation on the execution path. This means updates get
validated prior to being executed. There were quite a few tests that were not
working against Amazon DDB. These tests I considered broken and as such this
commit adapts them such that they pass against Amazon DDB.
test_update_item_on_map()
=> One of the SET actions would try to set a nested element by specifying the nesting on the path
rather than by putting a map as a value for a non-existent key. This got changed.
test_item_size_is_under_400KB
=> Used the keyword "item" which DDB doesn't like. Change to cont in order to keep the same sizings.
=> Secondly the size error messages differs a bit depending whether it is part of the update or part
of a put_item. For an update it should be:
Item size to update has exceeded the maximum allowed size
otherwise it is
Item size has exceeded the maximum allowed size'
test_remove_top_level_attribute
=> Used a keyword item. Use ExpressionAttributeNames
test_update_item_double_nested_remove
=> Used keywords name & first. Migrated to non-deprecated API and use ExpressionAttributeNames
test_update_item_set &
test_boto3_update_item_conditions_pass &
test_boto3_update_item_conditions_pass_because_expect_not_exists &
test_boto3_update_item_conditions_pass_because_expect_not_exists_by_compare_to_null &
test_boto3_update_item_conditions_pass_because_expect_exists_by_compare_to_not_null &
test_boto3_update_item_conditions_fail &
test_boto3_update_item_conditions_fail_because_expect_not_exists &
test_boto3_update_item_conditions_fail_because_expect_not_exists_by_compare_to_null
=> Were broken tests which had string literal instead of value placeholder
