Effective Dating Change in Mono Repo | Dataford Interview Questions

In a provided mono repo (backend, frontend, mocked DB with seed data), implement an effective-dating change that mutates DB records via an API, including the relevant frontend update and unit tests.

Asked in the coding challenge stage. Implement the core behavior as apply_effective_change(records, record_id, effective_date, changes).

Each record has id, valid_from, valid_to, and a fields dictionary. Date strings use YYYY-MM-DD; intervals are half-open: [valid_from, valid_to), and null means no end. If the date matches an existing version, merge the changes into that version. Otherwise, split the active version at the effective date, carrying forward unchanged fields. Return all records sorted by (id, valid_from) without mutating the input.

Constraints

1 <= len(records) <= 10^4
Each record contains id, valid_from, valid_to, and fields
Date strings use the YYYY-MM-DD format
Intervals are valid, non-overlapping, and half-open
The target record has an active version at effective_date
The input records and nested fields must not be mutated

Function Signature

def apply_effective_change(records, record_id, effective_date, changes):

Your question is Effective Dating Change in Mono Repo. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

In a provided mono repo (backend, frontend, mocked DB with seed data), implement an effective-dating change that mutates DB records via an API, including the relevant frontend update and unit tests.

Asked in the coding challenge stage. Implement the core behavior as apply_effective_change(records, record_id, effective_date, changes).

Constraints

1 <= len(records) <= 10^4
Each record contains id, valid_from, valid_to, and fields
Date strings use the YYYY-MM-DD format
Intervals are valid, non-overlapping, and half-open
The target record has an active version at effective_date
The input records and nested fields must not be mutated

Function Signature

def apply_effective_change(records, record_id, effective_date, changes):

Your question is Effective Dating Change in Mono Repo. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.