fix: Allow valid sql types to be used by Columns and Values (#63)

* fix: Allow valid sql types to be used by Columns and Values

* fix columns and lint

Author: taronish-stytch

.gitignore

@@ -1 +1,2 @@
 .coverprofile
+.idea

columns.go

@@ -1,6 +1,7 @@
 package scan
 
 import (
+	"database/sql/driver"
 	"errors"
 	"fmt"
 	"reflect"
@@ -99,7 +100,7 @@ func columnNames(model reflect.Value, strict bool, excluded ...string) []string
 
 		typeField := model.Type().Field(i)
 
-		if typeField.Type.Kind() == reflect.Struct {
+		if typeField.Type.Kind() == reflect.Struct && !isValidSqlValue(valField) {
 			embeddedNames := columnNames(valField, strict, excluded...)
 			names = append(names, embeddedNames...)
 			continue
@@ -120,7 +121,7 @@ func columnNames(model reflect.Value, strict bool, excluded ...string) []string
 			continue
 		}
 
-		if supportedColumnType(valField.Kind()) {
+		if supportedColumnType(valField.Kind()) || isValidSqlValue(valField) {
 			names = append(names, fieldName)
 		}
 	}
@@ -162,3 +163,16 @@ func supportedColumnType(k reflect.Kind) bool {
 		return false
 	}
 }
+
+func isValidSqlValue(v reflect.Value) bool {
+	// This method covers two cases in which we know the Value can be converted to sql:
+	// 1. It returns true for sql.driver's type check for types like time.Time
+	// 2. It implements the driver.Valuer interface allowing conversion directly
+	//    into sql statements
+	if driver.IsValue(v.Interface()) {
+		return true
+	}
+
+	valuerType := reflect.TypeOf((*driver.Valuer)(nil)).Elem()
+	return v.Type().Implements(valuerType)
+}

columns_test.go

@@ -1,8 +1,11 @@
 package scan
 
 import (
+	"database/sql/driver"
+	"fmt"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -269,6 +272,37 @@ func TestColumnsStoresOneCacheEntryPerInstance(t *testing.T) {
 	assert.Equal(t, 1, after-before, "Cache size grew unexpectedly")
 }
 
+func TestValuesWorkWithValidSqlValueTypes(t *testing.T) {
+	type coupon struct {
+		Value   int       `db:"value"`
+		Expires time.Time `db:"expires"`
+	}
+
+	c := &coupon{}
+	cols, err := Columns(c)
+	assert.NoError(t, err)
+	assert.EqualValues(t, []string{"value", "expires"}, cols)
+}
+
+type Pet struct {
+	Species string
+	Name    string
+}
+
+func (p Pet) Value() (driver.Value, error) {
+	return fmt.Sprintf("%s, a %s", p.Name, p.Species), nil
+}
+
+func TestValuesWorkWithDriverValuerImplementers(t *testing.T) {
+	type person struct {
+		Name string `db:"name"`
+		Pet  Pet    `db:"pet"`
+	}
+	cols, err := ColumnsStrict(&person{})
+	assert.NoError(t, err)
+	assert.EqualValues(t, []string{"name", "pet"}, cols)
+}
+
 func BenchmarkColumnsLargeStruct(b *testing.B) {
 	ls := &largeStruct{ID: "test", Index: 88, UUID: "test", IsActive: false, Balance: "test", Picture: "test", Age: 88, EyeColor: "test", Name: "test", Gender: "test", Company: "test", Email: "test", Phone: "test", Address: "test", About: "test", Registered: "test", Latitude: 0.566439688205719, Longitude: 0.48440760374069214, Greeting: "test", FavoriteFruit: "test", AID: "test", AIndex: 19, AUUID: "test", AIsActive: true, ABalance: "test", APicture: "test", AAge: 12, AEyeColor: "test", AName: "test", AGender: "test", ACompany: "test", AEmail: "test", APhone: "test", AAddress: "test", AAbout: "test", ARegistered: "test", ALatitude: 0.16338545083999634, ALongitude: 0.24648870527744293, AGreeting: "test", AFavoriteFruit: "test"}
 

values.go

@@ -50,15 +50,16 @@ func writeFields(val reflect.Value, m map[string][]int, index []int) {
 	numfield := val.NumField()
 
 	for i := 0; i < numfield; i++ {
-		if !val.Field(i).CanSet() {
+		valField := val.Field(i)
+		if !valField.CanSet() {
 			continue
 		}
 
 		field := typ.Field(i)
 		fieldIndex := append(index, field.Index...)
 
-		if field.Type.Kind() == reflect.Struct {
-			writeFields(val.Field(i), m, fieldIndex)
+		if field.Type.Kind() == reflect.Struct && !isValidSqlValue(valField) {
+			writeFields(valField, m, fieldIndex)
 			continue
 		}
 

values_test.go

@@ -3,6 +3,7 @@ package scan
 import (
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -107,6 +108,40 @@ func TestValuesReadsFromCacheFirst(t *testing.T) {
 	assert.EqualValues(t, []interface{}{"Brett"}, vals)
 }
 
+func TestValuesValidSqlTypes(t *testing.T) {
+	tNow := time.Now()
+	type coupon struct {
+		Value   int
+		Expires time.Time
+	}
+	c := &coupon{
+		Value:   25,
+		Expires: tNow,
+	}
+
+	vals, err := Values([]string{"Value", "Expires"}, c)
+	require.NoError(t, err)
+	assert.EqualValues(t, []interface{}{25, tNow}, vals)
+}
+
+func TestValuesDriverValuerImplementers(t *testing.T) {
+	type person struct {
+		Name string `db:"name"`
+		Pet  Pet    `db:"pet"`
+	}
+	p := &person{
+		Name: "Brett",
+		Pet: Pet{
+			Species: "dog",
+			Name:    "Mila",
+		},
+	}
+
+	vals, err := Values([]string{"Name", "Pet"}, p)
+	require.NoError(t, err)
+	assert.EqualValues(t, []interface{}{"Brett", Pet{Name: "Mila", Species: "dog"}}, vals)
+}
+
 // benchmarks
 
 func BenchmarkValuesLargeStruct(b *testing.B) {