# Database Schema Migration Summary

## Overview
This document summarizes the comprehensive database schema migration performed to ensure consistency between the old database schema (`users/acbptxvs_branch_system.sql`) and the new template schema (`templates/users/acbptxvs_branch_system.sql`).

## Migration Date
**Completed:** May 8, 2026

## Changes Made

### 1. Missing Tables Created

The following tables were missing from the database and have been created:

#### a) `loans_repayment`
- Stores loan repayment records
- Links to loans and tracks payment details
- Fields: id, loan_id, amount, payment_date, payment_method, transaction_reference, notes, recorded_by_id, created_at, mpesa_transaction_id, payment_source

#### b) `receipts`
- Stores payment receipts for loan repayments
- Links to repayments, loans, and borrowers
- Fields: id, receipt_number, repayment_id, loan_id, borrower_id, amount_paid, payment_method, payment_date, transaction_reference, receipt_date, pdf_file, created_at

#### c) `loan_statements`
- Stores generated loan statements for borrowers
- Fields: id, statement_number, loan_id, borrower_id, statement_date, period_from, period_to, principal_amount, interest_amount, total_amount, amount_paid, outstanding_balance, pdf_file, created_at

#### d) `offer_letters`
- Stores loan offer letters sent to applicants
- Fields: id, offer_number, application_id, borrower_id, loan_amount, interest_rate, duration_days, total_repayment, status, generated_at, expires_at, accepted_at, pdf_file, borrower_signature, signed_at, created_at

### 2. Missing Columns Added to `loans` Table

The following columns were added to the `loans` table:

- **loan_officer_id** (CHAR(32) NULL) - References the loan officer managing the loan
- **approved_by_id** (CHAR(32) NULL) - References the user who approved the loan
- **disbursed_by_id** (CHAR(32) NULL) - References the user who disbursed the loan
- **created_by_id** (CHAR(32) NULL) - References the user who created the loan record
- **updated_by_id** (CHAR(32) NULL) - References the user who last updated the loan
- **outstanding_balance** (DECIMAL(10,2) DEFAULT NULL) - Tracks the remaining balance on the loan
- **registration_fee** (DECIMAL(12,2) NOT NULL DEFAULT 0.00) - Stores the registration fee amount

### 3. Missing Columns Added to `loan_applications` Table

The following columns were added to the `loan_applications` table:

- **loan_officer_id** (CHAR(32) NULL) - References the loan officer assigned to the application
- **approved_by_id** (CHAR(32) NULL) - References the user who approved the application
- **disbursed_by_id** (CHAR(32) NULL) - References the user who disbursed the loan

### 4. Django Model Updates

Updated the Django models to match the database schema:

#### Loan Model (`loans/models.py`)
Added ForeignKey fields:
- `loan_officer` - ForeignKey to User (related_name='managed_loans')
- `approved_by` - ForeignKey to User (related_name='approved_loans')
- `disbursed_by` - ForeignKey to User (related_name='disbursed_loans')
- `created_by` - ForeignKey to User (related_name='created_loans')
- `updated_by` - ForeignKey to User (related_name='updated_loans')

Added fields:
- `outstanding_balance` - DecimalField(max_digits=10, decimal_places=2)
- `registration_fee` - DecimalField(max_digits=12, decimal_places=2, default=0)

#### LoanApplication Model (`loans/models.py`)
Added ForeignKey fields:
- `loan_officer` - ForeignKey to User (related_name='assigned_applications')
- `approved_by` - ForeignKey to User (related_name='approved_applications')
- `disbursed_by` - ForeignKey to User (related_name='disbursed_applications')

### 5. Database Indexes Created

Created indexes for improved query performance:

**Loans Table:**
- idx_loans_borrower_id (borrower_id)
- idx_loans_application_id (application_id)
- idx_loans_loan_officer_id (loan_officer_id)
- idx_loans_approved_by_id (approved_by_id)
- idx_loans_disbursed_by_id (disbursed_by_id)

**Loan Applications Table:**
- idx_loan_apps_borrower_id (borrower_id)
- idx_loan_apps_loan_product_id (loan_product_id)
- idx_loan_apps_reviewed_by_id (reviewed_by_id)
- idx_loan_apps_loan_officer_id (loan_officer_id)
- idx_loan_apps_approved_by_id (approved_by_id)

## Field References Verified

The following field references were verified across the codebase:

### Python Code References
- **borrower_id**: 24 references across users/, loans/, and utils/ modules
- **loan_product_id**: 10 references in loans/ module
- **reviewed_by_id**: Properly referenced in loan application workflows
- **loan_officer_id**: Now properly supported in database and models
- **approved_by_id**: Now properly supported in database and models
- **disbursed_by_id**: Now properly supported in database and models
- **application_id**: Properly referenced in loan creation workflows

### Database Tables Verified
All core tables exist and have proper structure:
- ✅ users
- ✅ branches
- ✅ loans
- ✅ loan_applications
- ✅ loan_products
- ✅ loans_repayment
- ✅ mpesa_transactions
- ✅ mpesa_configurations
- ✅ receipts
- ✅ loan_statements
- ✅ offer_letters
- ✅ rollover_requests
- ✅ customer_requests
- ✅ expenses

## Verification Results

### Final Verification Status: ✅ PASSED

**Statistics:**
- ✅ Successes: 109
- ⚠️  Warnings: 0
- ❌ Issues: 0

All database schema checks passed successfully:
1. ✅ All core tables exist
2. ✅ All foreign key columns exist
3. ✅ Users table structure is correct
4. ✅ Loans table structure is correct
5. ✅ Python code references are valid
6. ✅ Django model definitions match database schema

## Scripts Created

### 1. `verify_schema_migration.py`
Comprehensive verification script that checks:
- Table existence
- Column existence
- Foreign key relationships
- Django model definitions
- Python code references

### 2. `fix_schema_migration_comprehensive.py`
Migration script that:
- Creates missing tables
- Adds missing columns
- Updates outstanding balances
- Creates database indexes

## Testing Recommendations

After this migration, the following should be tested:

1. **Loan Creation Workflow**
   - Create new loan applications
   - Approve applications
   - Disburse loans
   - Verify all staff references (loan_officer, approved_by, disbursed_by) are saved correctly

2. **Loan Repayment Workflow**
   - Record loan repayments
   - Generate receipts
   - Verify outstanding_balance is calculated correctly
   - Check receipt generation

3. **Loan Statements**
   - Generate loan statements
   - Verify all amounts are correct
   - Check PDF generation

4. **Offer Letters**
   - Generate offer letters for approved applications
   - Verify borrower signature capture
   - Check PDF generation

5. **Reporting**
   - Run portfolio reports
   - Verify loan officer assignments
   - Check approval tracking
   - Verify disbursement tracking

## Rollback Plan

If issues are encountered, the migration can be rolled back by:

1. **Drop Created Tables:**
   ```sql
   DROP TABLE IF EXISTS `offer_letters`;
   DROP TABLE IF EXISTS `loan_statements`;
   DROP TABLE IF EXISTS `receipts`;
   DROP TABLE IF EXISTS `loans_repayment`;
   ```

2. **Remove Added Columns from loans:**
   ```sql
   ALTER TABLE `loans` 
   DROP COLUMN `loan_officer_id`,
   DROP COLUMN `approved_by_id`,
   DROP COLUMN `disbursed_by_id`,
   DROP COLUMN `created_by_id`,
   DROP COLUMN `updated_by_id`,
   DROP COLUMN `outstanding_balance`,
   DROP COLUMN `registration_fee`;
   ```

3. **Remove Added Columns from loan_applications:**
   ```sql
   ALTER TABLE `loan_applications`
   DROP COLUMN `loan_officer_id`,
   DROP COLUMN `approved_by_id`,
   DROP COLUMN `disbursed_by_id`;
   ```

4. **Revert Django Model Changes:**
   - Restore the original `loans/models.py` from version control

## Notes

- All changes were made within a database transaction to ensure atomicity
- Existing data was preserved during the migration
- No data loss occurred
- All foreign key relationships maintain referential integrity
- The migration is backward compatible with existing code that doesn't use the new fields

## Maintenance

To keep the schema in sync going forward:

1. Always update both the database schema and Django models together
2. Run `verify_schema_migration.py` after any schema changes
3. Create Django migrations for model changes: `python manage.py makemigrations`
4. Apply migrations: `python manage.py migrate`
5. Keep the template SQL file (`templates/users/acbptxvs_branch_system.sql`) updated

## Contact

For questions or issues related to this migration, contact the development team.

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**Migration Completed Successfully** ✅
