unique-constraint

README.md

@@ -63,6 +63,7 @@ List of common [validation arguments](https://pkg.go.dev/github.com/muonsoft/val
 * `validation.Bool()` - passes boolean value.
 * `validation.Number()` - passes any numeric value. At the moment it uses reflection for executing validation process.
 * `validation.String()` - passes string value.
+* `validation.Strings()` - passes slice of strings value.
 * `validation.Iterable()` - passes array, slice or a map. At the moment it uses reflection for executing validation process.
 * `validation.Countable()` - you can pass result of `len()` to use easy way of iterable validation based only on count of the elements.
 * `validation.Time()` - passes `time.Time` value.
@@ -76,6 +77,7 @@ For single value validation, you can use shorthand versions of the validation me
 * `validator.ValidateBool()`
 * `validator.ValidateNumber()`
 * `validator.ValidateString()`
+* `validator.ValidateStrings()`
 * `validator.ValidateIterable()`
 * `validator.ValidateCountable()`
 * `validator.ValidateTime()`
@@ -173,6 +175,7 @@ For a better experience with struct validation, you can use shorthand versions o
 * `validation.BoolProperty()`
 * `validation.NumberProperty()`
 * `validation.StringProperty()`
+* `validation.StringsProperty()`
 * `validation.IterableProperty()`
 * `validation.CountableProperty()`
 * `validation.TimeProperty()`
@@ -200,22 +203,25 @@ There are few ways to validate structs. The simplest one is to call the `validat
 ```golang
 document := Document{
     Title:    "",
-    Keywords: []string{""},
+    Keywords: []string{"", "book", "fantasy", "book"},
 }
 
 err := validator.Validate(
     validation.StringProperty("title", &document.Title, it.IsNotBlank()),
-    validation.CountableProperty("keywords", len(document.Keywords), it.HasCountBetween(2, 10)),
+    validation.CountableProperty("keywords", len(document.Keywords), it.HasCountBetween(5, 10)),
+    validation.StringsProperty("keywords", document.Keywords, it.HasUniqueValues()),
     validation.EachStringProperty("keywords", document.Keywords, it.IsNotBlank()),
 )
 
-violations := err.(validation.ViolationList)
-for _, violation := range violations {
-    fmt.Println(violation.Error())
+if violations, ok := validation.UnwrapViolationList(err); ok {
+    for violation := violations.First(); violation != nil; violation = violation.Next() {
+        fmt.Println(violation)
+    }
 }
 // Output:
 // violation at 'title': This value should not be blank.
-// violation at 'keywords': This collection should contain 2 elements or more.
+// violation at 'keywords': This collection should contain 5 elements or more.
+// violation at 'keywords': This collection should contain only unique elements.
 // violation at 'keywords[0]': This value should not be blank.
 ```
 
@@ -231,7 +237,9 @@ type Product struct {
 func (p Product) Validate(validator *validation.Validator) error {
     return validator.Validate(
         validation.StringProperty("name", &p.Name, it.IsNotBlank()),
-        validation.IterableProperty("tags", p.Tags, it.HasMinCount(1)),
+        validation.CountableProperty("tags", len(p.Tags), it.HasMinCount(5)),
+        validation.StringsProperty("tags", p.Tags, it.HasUniqueValues()),
+        validation.EachStringProperty("tags", p.Tags, it.IsNotBlank()),
         // this also runs validation on each of the components
         validation.IterableProperty("components", p.Components, it.HasMinCount(1)),
     )
@@ -253,6 +261,7 @@ func (c Component) Validate(validator *validation.Validator) error {
 func main() {
     p := Product{
         Name: "",
+        Tags: []string{"device", "", "phone", "device"},
         Components: []Component{
             {
                 ID:   1,
@@ -269,7 +278,9 @@ func main() {
     }
     // Output:
     // violation at 'name': This value should not be blank.
-    // violation at 'tags': This collection should contain 1 element or more.
+    // violation at 'tags': This collection should contain 5 elements or more.
+    // violation at 'tags': This collection should contain only unique elements.
+    // violation at 'tags[1]': This value should not be blank.
     // violation at 'components[0].name': This value should not be blank.
     // violation at 'components[0].tags': This collection should contain 1 element or more.
 }
@@ -313,13 +324,10 @@ Also, you can use helper function `validation.UnwrapViolationList()`.
 
 ```golang
 err := validator.Validate(/* validation arguments */)
-if err != nil {
-    violations, ok := validation.UnwrapViolationList(err)
-    if ok {
-        // handle violations
-    } else {
-        // handle internal error
-    }
+if violations, ok := validation.UnwrapViolationList(err); ok {
+    // handle violations
+} else if err != nil {
+    // handle internal error
 }
 ```
 
@@ -465,6 +473,7 @@ Everything you need to create a custom constraint is to implement one of the int
 * `BoolConstraint` - for validating boolean values;
 * `NumberConstraint` - for validating numeric values;
 * `StringConstraint` - for validating string values;
+* `StringsConstraint` - for validating slice of strings;
 * `IterableConstraint` - for validating iterable values: arrays, slices, or maps;
 * `CountableConstraint` - for validating iterable values based only on the count of elements;
 * `TimeConstraint` - for validating date\time values.

arguments.go

@@ -103,6 +103,20 @@ func StringProperty(name string, value *string, options ...Option) Argument {
 	return String(value, append([]Option{PropertyName(name)}, options...)...)
 }
 
+// Strings argument is used to validate slice of strings.
+func Strings(values []string, options ...Option) Argument {
+	return argumentFunc(func(arguments *Arguments) error {
+		arguments.addValidator(newStringsValidator(values, options))
+
+		return nil
+	})
+}
+
+// StringsProperty argument is an alias for Strings that automatically adds property name to the current scope.
+func StringsProperty(name string, values []string, options ...Option) Argument {
+	return Strings(values, append([]Option{PropertyName(name)}, options...)...)
+}
+
 // Iterable argument is used to validate arrays, slices, or maps. At the moment it uses reflection
 // to iterate over values. So you can expect a performance hit using this method. For better performance
 // it is recommended to make a custom type that implements the Validatable interface.

code/codes.go

@@ -33,6 +33,7 @@ const (
 	NotNil            = "notNil"
 	NotPositive       = "notPositive"
 	NotPositiveOrZero = "notPositiveOrZero"
+	NotUnique         = "notUnique"
 	NotValid          = "notValid"
 	ProhibitedIP      = "prohibitedIP"
 	TooEarly          = "tooEarly"

contraint.go

@@ -43,6 +43,12 @@ type StringConstraint interface {
 	ValidateString(value *string, scope Scope) error
 }
 
+// StringsConstraint is used to build constraints to validate an array or a slice of strings.
+type StringsConstraint interface {
+	Constraint
+	ValidateStrings(values []string, scope Scope) error
+}
+
 // IterableConstraint is used to build constraints for validation of iterables (arrays, slices, or maps).
 //
 // At this moment working with numbers is based on reflection.

example_test.go

@@ -98,6 +98,26 @@ func ExampleStringProperty() {
 	// violation at 'title': This value should not be blank.
 }
 
+func ExampleStrings() {
+	v := []string{"foo", "bar", "baz", "foo"}
+	err := validator.Validate(
+		validation.Strings(v, it.HasUniqueValues()),
+	)
+	fmt.Println(err)
+	// Output:
+	// violation: This collection should contain only unique elements.
+}
+
+func ExampleStringsProperty() {
+	v := Book{Keywords: []string{"foo", "bar", "baz", "foo"}}
+	err := validator.Validate(
+		validation.StringsProperty("keywords", v.Keywords, it.HasUniqueValues()),
+	)
+	fmt.Println(err)
+	// Output:
+	// violation at 'keywords': This collection should contain only unique elements.
+}
+
 func ExampleIterable() {
 	v := make([]string, 0)
 	err := validator.Validate(validation.Iterable(v, it.IsNotBlank()))
@@ -377,12 +397,13 @@ func ExampleValidator_Validate_basicStructValidation() {
 		Keywords []string
 	}{
 		Title:    "",
-		Keywords: []string{""},
+		Keywords: []string{"", "book", "fantasy", "book"},
 	}
 
 	err := validator.Validate(
 		validation.StringProperty("title", &document.Title, it.IsNotBlank()),
-		validation.CountableProperty("keywords", len(document.Keywords), it.HasCountBetween(2, 10)),
+		validation.CountableProperty("keywords", len(document.Keywords), it.HasCountBetween(5, 10)),
+		validation.StringsProperty("keywords", document.Keywords, it.HasUniqueValues()),
 		validation.EachStringProperty("keywords", document.Keywords, it.IsNotBlank()),
 	)
 
@@ -393,7 +414,8 @@ func ExampleValidator_Validate_basicStructValidation() {
 	}
 	// Output:
 	// violation at 'title': This value should not be blank.
-	// violation at 'keywords': This collection should contain 2 elements or more.
+	// violation at 'keywords': This collection should contain 5 elements or more.
+	// violation at 'keywords': This collection should contain only unique elements.
 	// violation at 'keywords[0]': This value should not be blank.
 }
 

example_validatable_struct_test.go

@@ -17,7 +17,9 @@ type Product struct {
 func (p Product) Validate(validator *validation.Validator) error {
 	return validator.Validate(
 		validation.StringProperty("name", &p.Name, it.IsNotBlank()),
-		validation.IterableProperty("tags", p.Tags, it.HasMinCount(1)),
+		validation.CountableProperty("tags", len(p.Tags), it.HasMinCount(5)),
+		validation.StringsProperty("tags", p.Tags, it.HasUniqueValues()),
+		validation.EachStringProperty("tags", p.Tags, it.IsNotBlank()),
 		// this also runs validation on each of the components
 		validation.IterableProperty("components", p.Components, it.HasMinCount(1)),
 	)
@@ -39,6 +41,7 @@ func (c Component) Validate(validator *validation.Validator) error {
 func ExampleValidator_ValidateValidatable_validatableStruct() {
 	p := Product{
 		Name: "",
+		Tags: []string{"device", "", "phone", "device"},
 		Components: []Component{
 			{
 				ID:   1,
@@ -56,7 +59,9 @@ func ExampleValidator_ValidateValidatable_validatableStruct() {
 	}
 	// Output:
 	// violation at 'name': This value should not be blank.
-	// violation at 'tags': This collection should contain 1 element or more.
+	// violation at 'tags': This collection should contain 5 elements or more.
+	// violation at 'tags': This collection should contain only unique elements.
+	// violation at 'tags[1]': This value should not be blank.
 	// violation at 'components[0].name': This value should not be blank.
 	// violation at 'components[0].tags': This collection should contain 1 element or more.
 }

is/data.go

@@ -6,3 +6,21 @@ import "encoding/json"
 func JSON(value string) bool {
 	return json.Valid([]byte(value))
 }
+
+// UniqueStrings checks that slice of strings has unique values.
+func UniqueStrings(values []string) bool {
+	if len(values) == 0 {
+		return true
+	}
+
+	uniques := make(map[string]struct{}, len(values))
+
+	for _, value := range values {
+		if _, exists := uniques[value]; exists {
+			return false
+		}
+		uniques[value] = struct{}{}
+	}
+
+	return true
+}

is/data_example_test.go

@@ -13,3 +13,13 @@ func ExampleJSON() {
 	// true
 	// false
 }
+
+func ExampleUniqueStrings() {
+	fmt.Println(is.UniqueStrings([]string{}))
+	fmt.Println(is.UniqueStrings([]string{"one", "two", "three"}))
+	fmt.Println(is.UniqueStrings([]string{"one", "two", "one"}))
+	// Output:
+	// true
+	// true
+	// false
+}