Refactor modifiers into its own package

attr_modifiers.go

@@ -1,66 +0,0 @@
-package ksql
-
-import (
-	"context"
-	"database/sql/driver"
-	"fmt"
-)
-
-// Here we keep all the registered modifier
-var modifiers = map[string]AttrModifier{
-	"json": jsonModifier{},
-}
-
-// RegisterAttrModifier allow users to add custom modifiers on startup
-// it is recommended to do this inside an init() function.
-func RegisterAttrModifier(key string, modifier AttrModifier) {
-	_, found := modifiers[key]
-	if found {
-		panic(fmt.Errorf("KSQL: cannot register modifier '%s' name is already in use", key))
-	}
-
-	modifiers[key] = modifier
-}
-
-// AttrModifier describes the two operations required to serialize and deserialize an object from the database.
-type AttrModifier interface {
-	AttrScan(ctx context.Context, opInfo OpInfo, attrPtr interface{}, dbValue interface{}) error
-	AttrValue(ctx context.Context, opInfo OpInfo, inputValue interface{}) (outputValue interface{}, _ error)
-}
-
-// OpInfo contains information that might be used by a modifier to determine how it should behave.
-type OpInfo struct {
-	// A string version of the name of one of
-	// the methods of the `ksql.Provider` interface, e.g. `Insert` or `Query`
-	Method string
-
-	// The string representing the current underlying database, e.g.:
-	// "postgres", "sqlite3", "mysql" or "sqlserver".
-	DriverName string
-}
-
-// attrModifier is the wrapper that allow us to intercept the Scan and Value processes
-// so we can run the modifiers instead of allowing the database driver to use
-// its default behavior.
-//
-// For that this struct implements both the `sql.Scanner` and `sql.Valuer` interfaces.
-type attrModifier struct {
-	ctx context.Context
-
-	// When Scanning this value should be a pointer to the attribute
-	// and when "Valuing" it should just be the actual value
-	attr interface{}
-
-	modifierName string
-	opInfo       OpInfo
-}
-
-// Scan implements the sql.Scanner interface
-func (a attrModifier) Scan(dbValue interface{}) error {
-	return modifiers[a.modifierName].AttrScan(a.ctx, a.opInfo, a.attr, dbValue)
-}
-
-// Value implements the sql.Valuer interface
-func (a attrModifier) Value() (driver.Value, error) {
-	return modifiers[a.modifierName].AttrValue(a.ctx, a.opInfo, a.attr)
-}

internal/modifiers/attr_modifiers.go

@@ -0,0 +1,32 @@
+package modifiers
+
+import (
+	"context"
+	"database/sql/driver"
+)
+
+// AttrWrapper is the wrapper that allow us to intercept the Scan and Value processes
+// so we can run the modifiers instead of allowing the database driver to use
+// its default behavior.
+//
+// For that this struct implements both the `sql.Scanner` and `sql.Valuer` interfaces.
+type AttrWrapper struct {
+	Ctx context.Context
+
+	// When Scanning this value should be a pointer to the attribute
+	// and when "Valuing" it should just be the actual value
+	Attr interface{}
+
+	Modifier AttrModifier
+	OpInfo   OpInfo
+}
+
+// Scan implements the sql.Scanner interface
+func (a AttrWrapper) Scan(dbValue interface{}) error {
+	return a.Modifier.AttrScan(a.Ctx, a.OpInfo, a.Attr, dbValue)
+}
+
+// Value implements the sql.Valuer interface
+func (a AttrWrapper) Value() (driver.Value, error) {
+	return a.Modifier.AttrValue(a.Ctx, a.OpInfo, a.Attr)
+}

internal/modifiers/contract.go

@@ -0,0 +1,20 @@
+package modifiers
+
+import "context"
+
+// AttrModifier describes the two operations required to serialize and deserialize an object from the database.
+type AttrModifier interface {
+	AttrScan(ctx context.Context, opInfo OpInfo, attrPtr interface{}, dbValue interface{}) error
+	AttrValue(ctx context.Context, opInfo OpInfo, inputValue interface{}) (outputValue interface{}, _ error)
+}
+
+// OpInfo contains information that might be used by a modifier to determine how it should behave.
+type OpInfo struct {
+	// A string version of the name of one of
+	// the methods of the `ksql.Provider` interface, e.g. `Insert` or `Query`
+	Method string
+
+	// The string representing the current underlying database, e.g.:
+	// "postgres", "sqlite3", "mysql" or "sqlserver".
+	DriverName string
+}

internal/modifiers/global_modifiers.go

@@ -0,0 +1,35 @@
+package modifiers
+
+import (
+	"fmt"
+	"sync"
+)
+
+// Here we keep all the registered modifiers
+var modifiers sync.Map
+
+func init() {
+	// These are the builtin modifiers
+	modifiers.Store("json", jsonModifier{})
+}
+
+// RegisterAttrModifier allow users to add custom modifiers on startup
+// it is recommended to do this inside an init() function.
+func RegisterAttrModifier(key string, modifier AttrModifier) {
+	_, found := modifiers.Load(key)
+	if found {
+		panic(fmt.Errorf("KSQL: cannot register modifier '%s' name is already in use", key))
+	}
+
+	modifiers.Store(key, modifier)
+}
+
+func LoadGlobalModifier(key string) (AttrModifier, error) {
+	rawModifier, _ := modifiers.Load(key)
+	modifier, ok := rawModifier.(AttrModifier)
+	if !ok {
+		return nil, fmt.Errorf("no modifier found with name '%s'", key)
+	}
+
+	return modifier, nil
+}

internal/modifiers/json_modifier.go

@@ -1,4 +1,4 @@
-package ksql
+package modifiers
 
 import (
 	"context"

internal/structs/structs.go

@@ -5,6 +5,8 @@ import (
 	"reflect"
 	"strings"
 	"sync"
+
+	"github.com/vingarcia/ksql/internal/modifiers"
 )
 
 // StructInfo stores metainformation of the struct
@@ -20,10 +22,10 @@ type StructInfo struct {
 // information regarding a specific field
 // of a struct.
 type FieldInfo struct {
-	Name         string
-	Index        int
-	Valid        bool
-	ModifierName string
+	Name     string
+	Index    int
+	Valid    bool
+	Modifier modifiers.AttrModifier
 }
 
 // ByIndex returns either the *FieldInfo of a valid
@@ -232,7 +234,7 @@ func (p PtrConverter) Convert(destType reflect.Type) (reflect.Value, error) {
 //
 // This should save several calls to `Field(i).Tag.Get("foo")`
 // which improves performance by a lot.
-func getTagNames(t reflect.Type) (StructInfo, error) {
+func getTagNames(t reflect.Type) (_ StructInfo, err error) {
 	info := StructInfo{
 		byIndex: map[int]*FieldInfo{},
 		byName:  map[string]*FieldInfo{},
@@ -249,10 +251,13 @@ func getTagNames(t reflect.Type) (StructInfo, error) {
 		}
 
 		tags := strings.Split(name, ",")
-		var modifierName string
+		var modifier modifiers.AttrModifier
 		if len(tags) > 1 {
 			name = tags[0]
-			modifierName = tags[1]
+			modifier, err = modifiers.LoadGlobalModifier(tags[1])
+			if err != nil {
+				return StructInfo{}, fmt.Errorf("attribute contains invalid modifier name: %w", err)
+			}
 		}
 
 		if _, found := info.byName[name]; found {
@@ -263,9 +268,9 @@ func getTagNames(t reflect.Type) (StructInfo, error) {
 		}
 
 		info.add(FieldInfo{
-			Name:         name,
-			Index:        i,
-			ModifierName: modifierName,
+			Name:     name,
+			Index:    i,
+			Modifier: modifier,
 		})
 	}
 

ksql.go

@@ -11,6 +11,7 @@ import (
 	"unicode"
 
 	"github.com/pkg/errors"
+	"github.com/vingarcia/ksql/internal/modifiers"
 	"github.com/vingarcia/ksql/internal/structs"
 	"github.com/vingarcia/ksql/ksqltest"
 )
@@ -718,13 +719,13 @@ func buildInsertQuery(
 		recordValue := recordMap[col]
 		params[i] = recordValue
 
-		modifierName := info.ByName(col).ModifierName
-		if modifierName != "" {
-			params[i] = attrModifier{
-				ctx:          ctx,
-				attr:         recordValue,
-				modifierName: modifierName,
-				opInfo: OpInfo{
+		modifier := info.ByName(col).Modifier
+		if modifier != nil {
+			params[i] = modifiers.AttrWrapper{
+				Ctx:      ctx,
+				Attr:     recordValue,
+				Modifier: modifier,
+				OpInfo: modifiers.OpInfo{
 					DriverName: dialect.DriverName(),
 					Method:     "Insert",
 				},
@@ -827,13 +828,13 @@ func buildUpdateQuery(
 	for i, k := range keys {
 		recordValue := recordMap[k]
 
-		modifierName := info.ByName(k).ModifierName
-		if modifierName != "" {
-			recordValue = attrModifier{
-				ctx:          ctx,
-				attr:         recordValue,
-				modifierName: modifierName,
-				opInfo: OpInfo{
+		modifier := info.ByName(k).Modifier
+		if modifier != nil {
+			recordValue = modifiers.AttrWrapper{
+				Ctx:      ctx,
+				Attr:     recordValue,
+				Modifier: modifier,
+				OpInfo: modifiers.OpInfo{
 					DriverName: dialect.DriverName(),
 					Method:     "Update",
 				},
@@ -1032,12 +1033,12 @@ func getScanArgsForNestedStructs(
 			if fieldInfo.Valid {
 				valueScanner = nestedStructValue.Field(fieldInfo.Index).Addr().Interface()
 
-				if fieldInfo.ModifierName != "" {
-					valueScanner = &attrModifier{
-						ctx:          ctx,
-						attr:         valueScanner,
-						modifierName: fieldInfo.ModifierName,
-						opInfo: OpInfo{
+				if fieldInfo.Modifier != nil {
+					valueScanner = &modifiers.AttrWrapper{
+						Ctx:      ctx,
+						Attr:     valueScanner,
+						Modifier: fieldInfo.Modifier,
+						OpInfo: modifiers.OpInfo{
 							DriverName: dialect.DriverName(),
 							// We will not differentiate between Query, QueryOne and QueryChunks
 							// if we did this could lead users to make very strange modifiers
@@ -1062,12 +1063,12 @@ func getScanArgsFromNames(ctx context.Context, dialect Dialect, names []string,
 		valueScanner := nopScannerValue
 		if fieldInfo.Valid {
 			valueScanner = v.Field(fieldInfo.Index).Addr().Interface()
-			if fieldInfo.ModifierName != "" {
-				valueScanner = &attrModifier{
-					ctx:          ctx,
-					attr:         valueScanner,
-					modifierName: fieldInfo.ModifierName,
-					opInfo: OpInfo{
+			if fieldInfo.Modifier != nil {
+				valueScanner = &modifiers.AttrWrapper{
+					Ctx:      ctx,
+					Attr:     valueScanner,
+					Modifier: fieldInfo.Modifier,
+					OpInfo: modifiers.OpInfo{
 						DriverName: dialect.DriverName(),
 						// We will not differentiate between Query, QueryOne and QueryChunks
 						// if we did this could lead users to make very strange modifiers

test_adapters.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 
 	"github.com/pkg/errors"
+	"github.com/vingarcia/ksql/internal/modifiers"
 	tt "github.com/vingarcia/ksql/internal/testtools"
 	"github.com/vingarcia/ksql/nullable"
 )
@@ -2799,11 +2800,13 @@ func getUserByID(db DBAdapter, dialect Dialect, result *user, id uint) error {
 		return sql.ErrNoRows
 	}
 
-	value := attrModifier{
-		ctx:          context.TODO(),
-		attr:         &result.Address,
-		modifierName: "json",
-		opInfo: OpInfo{
+	modifier, _ := modifiers.LoadGlobalModifier("json")
+
+	value := modifiers.AttrWrapper{
+		Ctx:      context.TODO(),
+		Attr:     &result.Address,
+		Modifier: modifier,
+		OpInfo: modifiers.OpInfo{
 			DriverName: dialect.DriverName(),
 			// We will not differentiate between Query, QueryOne and QueryChunks
 			// if we did this could lead users to make very strange modifiers