Chaitanya - Purchase request form enhancement

[csk731]

Description

Implements backend validation, error handling, and structured error responses for the Purchase Request APIs to align with the frontend validation, feedback, and confirmation flow. Validation covers required fields (project, material, quantity, priority), data types (ObjectIds, numeric quantity), and business rules (quantity > 0, valid priority). All validation errors return a consistent { field, message } structure so the frontend can show field-specific inline errors.

Related PRS (if any):

To test this backend PR you need to checkout the #4814 frontend PR.

Main changes explained:

• Update HGNRest/src/controllers/bmdashboard/bmMaterialsController.js – Adds validation in bmPurchaseMaterials:
  Required fields: projectId, matTypeId, quantity, priority, requestorId. ObjectId checks for projectId, matTypeId, requestorId. Quantity: must be a valid number and > 0. Priority: must be Low, Medium, or High. All validation errors returned as { field, message } for field-specific frontend display 500 errors handled consistently

How to test:

1. Check out the current branch.
2. Run npm install and start the backend API locally.
3. Ensure the frontend PR #4814 is checked out and running.
4. Log in as an admin user.
5. Go to /bmdashboard/materials/purchase.
6. Valid submission: Submit a valid form – expect 201 and a successful purchase record.
7. Check for worst cases: Invalid Project/ Material/Quantity/Priority. Backend Service Validates these all along with Frontend Service.

[Anusha-Gali]

Hi Chaitanya,

I have reviewed your PR locally and it works as expected. Find my comment in frontend pr: OneCommunityGlobal/HighestGoodNetworkApp#4814 (review)