73 lines
1.8 KiB
Go
73 lines
1.8 KiB
Go
// Copyright (c) 2023 Sumner Evans
|
|
//
|
|
// This Source Code Form is subject to the terms of the Mozilla Public
|
|
// License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
|
|
|
|
package dbutil
|
|
|
|
// RowIter is a wrapper for [Rows] that allows conveniently iterating over rows
|
|
// with a predefined scanner function.
|
|
type RowIter[T any] interface {
|
|
// Iter iterates over the rows and calls the given function for each row.
|
|
//
|
|
// If the function returns false, the iteration is stopped.
|
|
// If the function returns an error, the iteration is stopped and the error is
|
|
// returned.
|
|
Iter(func(T) (bool, error)) error
|
|
|
|
// AsList collects all rows into a slice.
|
|
AsList() ([]T, error)
|
|
}
|
|
|
|
type rowIterImpl[T any] struct {
|
|
Rows
|
|
ConvertRow func(Scannable) (T, error)
|
|
}
|
|
|
|
// NewRowIter creates a new RowIter from the given Rows and scanner function.
|
|
func NewRowIter[T any](rows Rows, convertFn func(Scannable) (T, error)) RowIter[T] {
|
|
return &rowIterImpl[T]{Rows: rows, ConvertRow: convertFn}
|
|
}
|
|
|
|
func ScanSingleColumn[T any](rows Scannable) (val T, err error) {
|
|
err = rows.Scan(&val)
|
|
return
|
|
}
|
|
|
|
type NewableDataStruct[T any] interface {
|
|
DataStruct[T]
|
|
New() T
|
|
}
|
|
|
|
func ScanDataStruct[T NewableDataStruct[T]](rows Scannable) (T, error) {
|
|
var val T
|
|
return val.New().Scan(rows)
|
|
}
|
|
|
|
func (i *rowIterImpl[T]) Iter(fn func(T) (bool, error)) error {
|
|
if i == nil || i.Rows == nil {
|
|
return nil
|
|
}
|
|
defer i.Rows.Close()
|
|
|
|
for i.Rows.Next() {
|
|
if item, err := i.ConvertRow(i.Rows); err != nil {
|
|
return err
|
|
} else if cont, err := fn(item); err != nil {
|
|
return err
|
|
} else if !cont {
|
|
break
|
|
}
|
|
}
|
|
return i.Rows.Err()
|
|
}
|
|
|
|
func (i *rowIterImpl[T]) AsList() (list []T, err error) {
|
|
err = i.Iter(func(item T) (bool, error) {
|
|
list = append(list, item)
|
|
return true, nil
|
|
})
|
|
return
|
|
}
|