Enhance Sp7 Query Builder to Support Calculated Fields

[Copilot]

This PR implements support for calculated fields in the Sp7 Query Builder, bringing feature parity with the Sp6 query builder for calculated field functionality.

Problem

The Sp7 query builder was unable to query calculated fields like actualCountAmt, totalPreps, isOnLoan, etc., even though these fields were already computed and available in the API. Users needed to access these fields through the query builder interface to create sophisticated queries for collection management workflows.

Solution

Enhanced the query field specification system to recognize and generate SQL expressions for calculated fields:

Key Changes

1. Enhanced PRECALCULATED_FIELDS Dictionary: Updated to include all calculated fields with proper camelCase naming to match frontend schema expectations:

   • Preparation: actualCountAmt, isOnLoan, isOnGift, isOnDisposal, isOnExchangeOut, isOnExchangeIn
   • Loan: totalPreps, totalItems, unresolvedPreps, unresolvedItems, resolvedPreps, resolvedItems
   • Accession: totalCountAmt, actualTotalCountAmt, collectionObjectCount, preparationCount
   • Disposal/Gift/ExchangeOut/Deaccession: totalPreps, totalItems

2. Implemented get_calculated_field_expression() Function: Creates SQLAlchemy expressions for calculated fields using subqueries. For example:

   # actualCountAmt = countamt - (gift_sum + exchangeout_sum + disposal_sum)
   gift_sum = select(func.coalesce(func.sum(models.GiftPreparation.quantity), 0)).where(
       models.GiftPreparation.preparationid == orm_model.preparationid
   ).scalar_subquery()

3. Fixed Query Builder Integration: Updated QueryFieldSpec.add_spec_to_query() to properly handle calculated fields when regular model attributes are not found, falling back to generated SQL expressions.

4. Corrected Model Field References: Fixed all SQLAlchemy model field references to use correct lowercase naming convention (preparationid, loanid, etc.).

Technical Implementation

The solution uses SQLAlchemy subqueries to calculate field values dynamically within queries, ensuring:

• Real-time accuracy: Values are computed at query time, not cached
• Consistency: Same calculation logic as existing API calculated fields
• Performance: Efficient subquery-based calculations
• Integration: Seamless compatibility with query builder's join and filter mechanisms

Example Usage

Users can now create queries like:

• "Find all Preparations where actualCountAmt > 0"
• "List Loans where unresolvedPreps > 5"
• "Show Accessions with totalCountAmt != actualTotalCountAmt"

Validation

Added validate_calculated_fields.py script to verify implementation correctness without requiring full Django environment setup. All tests pass, confirming proper integration between backend calculations and frontend schema expectations.

This enhancement resolves the gap between Sp6 and Sp7 query builder capabilities, enabling sophisticated collection management queries using calculated fields.

Created from VS Code via the GitHub Pull Request extension.

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