Backend: Assessment results

GitHub Issue: #228

Backend task for the results page (GET /assessments/{assessmentId}/results, POST /written-test-grades) – check the calculation rules against the API spec and DB structure, permissions, implement, and verify with a hand-calculated example.

Docs: Assessment results Spec: GET /assessments/{assessmentId}/results (getAssessmentResults), POST /assessments/{assessmentId}/written-test-grades (setAssessmentWrittenTestGrades), AssessmentResults, AssessmentWrittenTestGrade in api-docs/openapi.yaml DB: AssessmentGrades, AssessmentCandidates, AssessmentWrittenTestGrades, AssessmentBoardMembers in api/database/create_schema.sql

1. Double check API spec and DB structure

• Each results table row in the docs maps to a field: Grupna diskusija → groupDiscussion, prvi kontakt → firstContact, argumentacija → argumentation, Pismena provjera znanja → writtenTest, Zbroj → sum, Intervju → interview, UKUPNO → total.
• Calculation rules in the spec vs the docs:
  • activity value = the average POGODNOST across board members who entered grades (including removed members); null if there are none
  • argumentation disabled → copy firstContact
  • Zbroj = the average of the non-null group discussion, first contact, argumentation and written test values (calculated even when some are missing; the docs follow the spec, not Figma)
  • UKUPNO = the average of the non-null Zbroj and Intervju
  • unrounded values (docs recommendation). Write this into the spec.
• Pregled unosa članova komisije: the spec lists only graded activities (argumentation only if enabled; no presentation / interview-notes). The docs say this is an open question. Confirm. An individual activity counts as completed only when it’s completed for every candidate.
• Header data (brand · date · name): from the detail endpoint, or add it here?
• CSV export is done in the frontend. Confirm the response has everything the CSV needs.
• Roles and permissions: results are visible to Trainers (assessments.access-all) and to evaluators in the komisija. Editing the written test grade needs assessments.edit. Check against the docs.
• DB: AssessmentWrittenTestGrades.Grade DECIMAL(2,1) 0–3, one row per candidate that has a grade (no row = no grade). The docs only guess this range from Figma. Confirm. It’s a separate table so its FK blocks removing a candidate who has a grade. Grades of removed board members stay in AssessmentGrades and are counted.

2. Implementation

• Roles and permissions: GET → assessments.access-all or an active board member; POST → assessments.edit.
• DB: one query for all grades of the assessment, then calculate in code with the shared helpers (category → POGODNOST per member and candidate → average across members).
• Board member overview: active members only, using each form’s status helper (Grupna diskusija, prvi kontakt, argumentacija, Strukturirani intervju – ocijene).
• POST /written-test-grades: update only the listed candidates (null clears the grade); each candidateId must belong to the assessment (404); grade validated 0–3 with one decimal; return the recalculated results. One MERGE on AssessmentWrittenTestGrades, no transaction: a value inserts or updates the row, null deletes it. FK error 547 (candidate removed in the meantime) → 404; unique violation (saved twice at once) → retry once.

3. Verify implementation against spec

• Response shapes and status codes match both operations.
• Results checked against an example calculated by hand: 2 board members (one removed after grading), 3 candidates, some grades missing, argumentation on and off.
• A candidate with no grades at all → every activity field and sum / total are null.
• Evaluator → POST 403. Writing a grade of 3.25 or 4 → 400.

Done when

The results page and CSV can be built from the API, and the numbers match the hand-calculated example.