Modeling Relational Data in DynamoDB (nested relationship) - amazon-dynamodb

Question

Entity Model:
I've read AWS Guide about create a Modeling Relational Data in DynamoDB. It's so confusing in my access pattern.
Access Pattern
+-------------------------------------------+------------+------------+
| Access Pattern | Params | Conditions |
+-------------------------------------------+------------+------------+
| Get TEST SUITE detail and check that |TestSuiteID | |
| USER_ID belongs to project has test suite | &UserId | |
+-------------------------------------------+------------+------------+
| Get TEST CASE detail and check that | TestCaseID | |
| USER_ID belongs to project has test case | &UserId | |
+-------------------------------------------+------------+------------+
| Remove PROJECT ID, all TEST SUITE | ProjectID | |
| AND TEST CASE also removed | &UserId | |
+-------------------------------------------+------------+------------+
So, I model a relational entity data as guide.
+-------------------------+---------------------------------+
| Primary Key | Attributes |
+-------------------------+ +
| PK | SK | |
+------------+------------+---------------------------------+
| user_1 | USER | FullName | |
+ + +----------------+----------------+
| | | John Doe | |
+ +------------+----------------+----------------+
| | prj_01 | JoinedDate | |
+ + +----------------+----------------+
| | | 2019-04-22 | |
+ +------------+----------------+----------------+
| | prj_02 | JoinedDate | |
+ + +----------------+----------------+
| | | 2019-05-26 | |
+------------+------------+----------------+----------------+
| user_2 | USER | FullName | |
+ + +----------------+----------------+
| | | Harry Potter | |
+ +------------+----------------+----------------+
| | prj_01 | JoinedDate | |
+ + +----------------+----------------+
| | | 2019-04-25 | |
+------------+------------+----------------+----------------+
| prj_01 | PROJECT | Name | Description |
+ + +----------------+----------------+
| | | Facebook Test | Do some stuffs |
+ +------------+----------------+----------------+
| | t_suite_01 | | |
+ + +----------------+----------------+
| | | | |
+------------+------------+----------------+----------------+
| prj_02 | PROJECT | Name | Description |
+ + +----------------+----------------+
| | | Instagram Test | ... |
+------------+------------+----------------+----------------+
| t_suite_01 | TEST_SUITE | Name | |
+ + +----------------+----------------+
| | | Test Suite 1 | |
+ +------------+----------------+----------------+
| | t_case_1 | | |
+ + +----------------+----------------+
| | | | |
+------------+------------+----------------+----------------+
| t_case_1 | TEST_CASE | Name | |
+ + +----------------+----------------+
| | | Test Case 1 | |
+------------+------------+----------------+----------------+
If I just have UserID and TestCaseId as a parameter, how could I get TestCase Detail and verify that UserId has permission.
I've thought about storing complex hierarchical data within a single item. Something likes this
+------------+-------------------------+
| t_suite_01 | user_1#prj_1 |
+------------+-------------------------+
| t_suite_02 | user_1#prj_2 |
+------------+-------------------------+
| t_case_01 | user_1#prj_1#t_suite_01 |
+------------+-------------------------+
| t_case_02 | user_2#prj_1#t_suite_01 |
+------------+-------------------------+
Question: What is the best way for this case? I appreciate if you could give me some suggestion for this approach (bow)

Answer 1

I think the schema below does what you want. Create a Partition Key only GSI on the "GSIPK" attribute and query as follows:
Get Test Suite Detail and Validate User: Query GSI - PK == ProjectId, FilterCondition [SK == TestSuiteId || PK == UserId]
Get Test Case Detail and Validate User: Query GSI - PK == TestCaseId, FilterCondition [SK = TestSuiteId:TestCaseId || PK = UserId]
Remove Project: Query GSI - PK == ProjectId, remove all items returned.
Queries 1 and 2 come back with 1 or 2 items. One is the detail item and the other is the user permissions for the test suite or test case. If only one item returns then its the detail item and the user has no access.

Answer 2

The first question you should ask is: why do I want to use key-value document DB over relational DB when I clearly have strong relations in my data?
The answer might be: I need a single-digit millisecond queries at any scale (millions of records). Or, I want to save money using dynamodb on-demand. If this is not the case, you might be better with a relational DB.
Let’s say you have to go for dynamodb. If so, most of patterns applicable for relational DBs are anti-patterns when it comes to NoSQL. There is a useful talk from last re-invent about design patterns for dynamodb and advice to watch it https://youtu.be/HaEPXoXVf2k.
For your data I’d think about taking similar approach, and having two tables: users and projects.
Projects should store sub-set of test suits as map of array of objects and test cases as map of array of objects. Plus you could add list of user ids in the map of strings. Of course you will need to maintain this list when users join or leave the project/s.
This should satisfy your access patterns.