feat: Add Avg, Min, and Max aggregate functions to DB Query

[oguzhankrcb]

Database Query Methods Refactoring

Summary

This PR refactors the database query aggregation methods to use a pointer pattern instead of returning values directly. This change provides better type safety and allows for more flexible error handling.

Key Changes

1. Pointer Pattern Implementation

We've refactored the aggregation methods to use a pointer pattern where the result is populated into a destination variable passed by reference:

• Avg(column string, dest any) error
• Sum(column string, dest any) error
• Min(column string, dest any) error
• Max(column string, dest any) error

2. New Sum Method

We've changed the Sum method to use pointer implementation:

// Sum calculates the sum of a column's values and populates the destination object.
func (r *Query) Sum(column string, dest any) error

3. Updated Method Signatures

All aggregation methods now follow the same pattern:

• Accept a column name as a string
• Accept a destination pointer (any type)
• Return an error if the operation fails

4. Type Safety Improvements

The implementation includes validation to ensure the destination parameter is a pointer:

destValue := reflect.ValueOf(dest)
if destValue.Kind() != reflect.Ptr {
    return errors.DatabaseUnsupportedType.Args(destValue.Kind(), "pointer")
}

Usage Examples

Before (hypothetical example)

sum, err := query.Sum("price")
if err != nil {
    return err
}
fmt.Printf("Total price: %d\n", sum)

After (current implementation)

// Calculate the sum of a column
var totalSum int64
err := query.Table("products").Sum("price", &totalSum)
if err != nil {
    return err
}
fmt.Printf("Total price: %d\n", totalSum)

// Calculate the average of a column
var avgPrice float64
err := query.Table("products").Avg("price", &avgPrice)
if err != nil {
    return err
}
fmt.Printf("Average price: %.2f\n", avgPrice)

// Calculate the minimum value of a column
var minPrice int64
err := query.Table("products").Min("price", &minPrice)
if err != nil {
    return err
}
fmt.Printf("Minimum price: %d\n", minPrice)

// Calculate the maximum value of a column
var maxPrice int64
err := query.Table("products").Max("price", &maxPrice)
if err != nil {
    return err
}
fmt.Printf("Maximum price: %d\n", maxPrice)

Return Types

All aggregation methods now return:

• error - indicating success or failure of the operation
• The actual result is populated into the destination pointer passed as a parameter

Implementation Details

The implementation uses the following approach:

1. Validate that the destination parameter is a non-nil pointer
2. Build a SQL query with the appropriate aggregation function (SUM, AVG, MIN, MAX)
3. Execute the query using the existing query infrastructure
4. Populate the result into the destination pointer
5. Return any errors that occurred during execution

Benefits

1. Type Safety: The pointer pattern ensures type compatibility at compile time
2. Consistency: All aggregation methods now follow the same pattern
3. Flexibility: Users can specify the exact type they want the result in
4. Error Handling: Clear error reporting when operations fail

Testing

All tests pass successfully with the new implementation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.73%. Comparing base (cfae10b) to head (558ae7f).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1240      +/-   ##
==========================================
- Coverage   66.09%   65.73%   -0.36%     
==========================================
  Files         248      248              
  Lines       17069    17185     +116     
==========================================
+ Hits        11282    11297      +15     
- Misses       5410     5511     +101     
  Partials      377      377              

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[hwbrzzl]

Thanks, pretty good.

[hwbrzzl]

We consider changing the Sum function to Sum(column string, dest any) error to adapt the int* and float* situation. Hence, Avag, Min, Max can do that as well. If it makes sense, could you optimize it in this PR simultaneously?

[oguzhankrcb]

Hello, I have changed the Sum methods signature and added tests and same for the other methods.

[hwbrzzl]

Could you precisely assert the value?

[oguzhankrcb]

fixed

[hwbrzzl]

Ditto

[oguzhankrcb]

fixed

[hwbrzzl]

Ditto

[oguzhankrcb]

fixed

[Copilot]

Pull Request Overview

This PR refactors database aggregation methods (Sum, Avg, Min, Max) to use a pointer-based pattern for improved type safety and error handling. The new implementation requires callers to pass a destination pointer that will be populated with the result, rather than returning the value directly.

Key changes:

• Refactored Sum method to accept a destination pointer parameter and return only an error
• Added three new aggregation methods: Avg, Min, and Max, all following the same pointer-based pattern
• Updated all contract interfaces, implementations, mocks, and tests to use the new signatures

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
contracts/database/orm/orm.go	Updated Query interface with new signatures for Sum and added Avg, Min, Max methods
contracts/database/db/db.go	Updated Query interface with new signatures for Sum and added Avg, Min, Max methods
database/gorm/query.go	Implemented pointer-based Sum, Avg, Min, Max with pointer validation
database/db/query.go	Implemented pointer-based Sum, Avg, Min, Max with pointer validation
mocks/database/orm/Query.go	Generated mock implementations for updated method signatures
mocks/database/db/Query.go	Generated mock implementations for updated method signatures
tests/models.go	Added Ratio field to User model for testing aggregation functions
tests/table.go	Added ratio column to user table schemas
tests/query_test.go	Updated Sum tests and added comprehensive tests for Avg, Min, Max
tests/db_test.go	Updated Sum tests and added comprehensive tests for Avg, Min, Max
tests/to_sql_test.go	Updated SQL assertions to include new ratio column
database/db/query_test.go	Updated unit tests for pointer-based aggregation methods

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[hwbrzzl]

Pretty good, thanks!

[hwbrzzl]

Hey @oguzhankrcb FYI, added you to the contributor list, looking forward to more amazing PRs, thanks again.