[VA Benefit Taxonomy] [Drupal] Prevent reciprocal Entity references for Pre-Requisite Benefits on VA Benefits Taxonomy terms

[davidmpickett]

Status

[2024-07-31] [Fran] Asked Daniel via Slack to async refine.

User Story or Problem Statement

AS AN Editor of the VA Benefit Taxonomy I NEED a safeguard to prevent the possibility of indicating a benefit relationship that is impossible in the real world

• It is currently possible to have two Benefit terms list each other as Pre-Requisites
• This does not make sense in a real-world benefit context, so should be prevented in Drupal

flowchart TB 
    X[houseboundAllowance] -->|field_va_benefit_prerequisite| Y[veteransPension]
    Y -->|field_va_benefit_prerequisite| X
    style X fill:#f2938c
    style Y fill:#f2938c    

Examples: Valid Pre-requisite relationships

These are from 18165

Model: Pre-requisite benefits

flowchart TB
    subgraph AB [Actual benefits]
    direction LR
        A(Benefit 1) -->|is a pre-requisite for| B(Benefit 2)
    end
    subgraph DE [Drupal entities]
    direction RL
    C[Term2] -->|field_va_benefit_prerequisite| D[Term1]
    style A fill:#00bde3,color:#fff
    style B fill:#00bde3,color:#fff
    style C fill:#f2938c
    style D fill:#f2938c
    end
    AB ~~~ DE

Example: VA health care

• A single benefit can be a prerequisite for multiple other benefits

  flowchart TB
  subgraph AB [Actual benefits]
  direction LR
      A(VA health care) -->|is a pre-requisite for| B(VA dental care)
      A -->|is a pre-requisite for| Z(VA vision care)
  end
  subgraph DE [Drupal entities]
  direction RL
  C[DentalCare] -->|field_va_benefit_prerequisite| D[healthcare]
  Y[VisionCare] -->|field_va_benefit_prerequisite| D
  style A fill:#00bde3,color:#fff
  style B fill:#00bde3,color:#fff
  style Z fill:#00bde3,color:#fff
  style C fill:#f2938c
  style D fill:#f2938c
  style Y fill:#f2938c
  end
  AB ~~~ DE

Counter Example: Housebound allowance

• A single benefit can have multiple (possible) prerequisites
• Current model does not specify when/how prerequisites apply

  flowchart TB
  subgraph AB [Actual benefits]
  direction LR
      A(Veterans Pension) -->|is a pre-requisite for| B(Housebound allowance)
      C(VA Survivors Pension) -->|is a pre-requisite for| B
  end
  subgraph DE [Drupal entities]
  direction RL
  X[houseboundAllowance] -->|field_va_benefit_prerequisite| Y[veteransPension]
  X -->|field_va_benefit_prerequisite| Z[survivorsPension]
  style A fill:#00bde3,color:#fff
  style B fill:#00bde3,color:#fff
  style C fill:#00bde3,color:#fff
  style X fill:#f2938c
  style Y fill:#f2938c
  style Z fill:#f2938c    
  end
  AB ~~~ DE

Proposed steps for Implementation

• Probably need to add a way for a Term to have awareness of Terms that are referencing it as Pre-requisite as a first step.
• Add validation to prevent saving Term1 if it lists as Pre-Requisite a Term2 which already lists Term1 as Pre-requisite
  • Needs error message review
  • Save validation is a stable and reliable
  • Not the best UX since an editor won't know they've done something wrong until they finish the rest of the form
• AND/OR Winnow options for field_va_benefit_prerequisite to remove Terms that list the current term as field_va_benefit_prerequisite
  • Way better UX (prevents error rather than helps user recover from error)
  • Winnowing uses javascript (i think) and can be flakier than save validation
  • Might need to still have save validation in addition

Acceptance Criteria

• [ ] It is no longer possible to save a VA Benefit Taxonomy term with a reciprocal pre-requisite reference to another term
• [ ] No regressions to current VA Benefit Taxonomy functionality
• [ ] Requires design review?
• [ ] Requires accessibility review?

[davidmpickett]

@dsasser @mmiddaugh @FranECross I took a first pass at drafting up this Drupal implementation ticket. Might need a little tweaking in the tasks and ACs, but pretty confident that the basic story is there.

[dsasser]

Engineering Pre-Refinement

Point estimate: 1 (Using the below solution)

We can achieve this using existing contrib module (already in use in the site), Entity Reference Validators. Below shows the configuration options for the pre-requisite field that the module provides:

And this is the result when the constraint is triggered: