5362614c3e
Introduces Field, Rule, ValidateAll, ResetFields, and AddError for declarative input validation. Includes built-in rules (Required, MinLen, MaxLen, Min, Max, Email, Pattern, Custom) and a signup example exercising the full API surface.
129 lines
2.7 KiB
Go
129 lines
2.7 KiB
Go
package via
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import (
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"fmt"
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"regexp"
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"strconv"
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"strings"
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)
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// Rule defines a single validation check for a Field.
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type Rule struct {
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validate func(val string) error
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}
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// Required rejects empty or whitespace-only values.
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func Required(msg ...string) Rule {
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m := "This field is required"
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if len(msg) > 0 {
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m = msg[0]
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}
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return Rule{func(val string) error {
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if strings.TrimSpace(val) == "" {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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// MinLen rejects values shorter than n characters.
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func MinLen(n int, msg ...string) Rule {
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m := fmt.Sprintf("Must be at least %d characters", n)
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if len(msg) > 0 {
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m = msg[0]
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}
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return Rule{func(val string) error {
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if len(val) < n {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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// MaxLen rejects values longer than n characters.
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func MaxLen(n int, msg ...string) Rule {
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m := fmt.Sprintf("Must be at most %d characters", n)
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if len(msg) > 0 {
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m = msg[0]
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}
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return Rule{func(val string) error {
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if len(val) > n {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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// Min parses the value as an integer and rejects values less than n.
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func Min(n int, msg ...string) Rule {
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m := fmt.Sprintf("Must be at least %d", n)
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if len(msg) > 0 {
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m = msg[0]
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}
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return Rule{func(val string) error {
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v, err := strconv.Atoi(val)
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if err != nil {
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return fmt.Errorf("%s", m)
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}
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if v < n {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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// Max parses the value as an integer and rejects values greater than n.
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func Max(n int, msg ...string) Rule {
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m := fmt.Sprintf("Must be at most %d", n)
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if len(msg) > 0 {
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m = msg[0]
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}
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return Rule{func(val string) error {
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v, err := strconv.Atoi(val)
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if err != nil {
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return fmt.Errorf("%s", m)
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}
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if v > n {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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// Pattern rejects values that don't match the regular expression re.
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func Pattern(re string, msg ...string) Rule {
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m := "Invalid format"
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if len(msg) > 0 {
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m = msg[0]
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}
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compiled := regexp.MustCompile(re)
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return Rule{func(val string) error {
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if !compiled.MatchString(val) {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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var emailRegexp = regexp.MustCompile(`^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$`)
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// Email rejects values that don't look like an email address.
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func Email(msg ...string) Rule {
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m := "Invalid email address"
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if len(msg) > 0 {
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m = msg[0]
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}
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return Rule{func(val string) error {
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if !emailRegexp.MatchString(val) {
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return fmt.Errorf("%s", m)
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}
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return nil
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}}
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}
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// Custom creates a rule from a user-provided validation function.
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// The function should return nil for valid input and an error for invalid input.
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func Custom(fn func(string) error) Rule {
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return Rule{validate: fn}
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}
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