add generic validators functions

validators.go

@@ -0,0 +1,114 @@
+package form
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+// validation errors
+var (
+	EInvalidInteger = errors.New("not a valid integer value")
+	EInvalidFloat   = errors.New("not a valid float value")
+	ERequired       = errors.New("this field is required")
+)
+
+// validLettersGeneric is a validator generator for checking
+// for valid letters in field
+func validLettersGeneric(Letters string, Error error) ValidatorFunc {
+	Callback := func(field FormField, ctx context.Context) error {
+		for _, Rune := range field.GetString() {
+			if strings.IndexRune(Letters, Rune) == -1 {
+				return Error
+			}
+		}
+		return nil
+	}
+	return Callback
+}
+
+// validRequired returns nil if there is text in the field.
+// If the field is empty it returns error.
+func validRequired(field FormField, ctx context.Context) error {
+	if field.GetString() == "" {
+		return ERequired
+	}
+	return nil
+}
+
+// validLength returns a string field validator that verifies if a string
+// length is between specified min and max values.
+func validLength(min, max int) ValidatorFunc {
+	var ELength = errors.New(
+		fmt.Sprintf("must be a string between %d and %d characters in length", min, max))
+	return func(field FormField, ctx context.Context) error {
+		if len(field.GetString()) != 0 && (len(field.GetString()) < min || len(field.GetString()) > max) {
+			return ELength
+		}
+		return nil
+	}
+}
+
+// validInt returns error if field does not contain a valid integer value
+func validInt(field FormField, ctx context.Context) error {
+	_, err := field.GetInt()
+	if err != nil {
+		return EInvalidInteger
+	}
+	return nil
+}
+
+// validBetween is a validator generator that makes sure field is
+// integer value within the specified range.
+func validBetween(min, max int) ValidatorFunc {
+	var EInvalidInterval = errors.New(
+		fmt.Sprintf("must be integer between %d and %d", min, max))
+	return func(field FormField, ctx context.Context) error {
+		value, err := field.GetInt()
+		if err != nil {
+			return err
+		}
+		if value < min || value > max {
+			return EInvalidInterval
+		}
+		return nil
+	}
+}
+
+// validFloat returns error if field does not contain a valid integer value
+func validFloat(field FormField, ctx context.Context) error {
+	_, err := field.GetFloat()
+	if err != nil {
+		return EInvalidFloat
+	}
+	return nil
+}
+
+// validBetweenFloat32 is a v alidator generator that makes sure field is
+// float64 value within the specified range.
+func validBetweenFloat(min, max float64) ValidatorFunc {
+	var EInvalidInterval = errors.New(
+		fmt.Sprintf("must be float value between %.2f and %.2f", min, max))
+	return func(field FormField, ctx context.Context) error {
+		value, err := field.GetFloat()
+		if err != nil {
+			return err
+		}
+		if value < min || value > max {
+			return EInvalidInterval
+		}
+		return nil
+	}
+}
+
+// validFieldEqualTo is a general purpose validator that checks
+// if two fields have the same value for verification purposes.
+func validFieldEqualTo(Other *FormField, err error) ValidatorFunc {
+	return func(field FormField, ctx context.Context) error {
+		if field.GetString() != Other.GetString() {
+			return err
+		}
+		return nil
+	}
+}