NumField, DoubleField, IntField

lib/src/common_fields.dart

@@ -23,7 +23,7 @@ class TextField extends Field<String> {
       renderer.visitTextField(this);
 
   @override
-  FutureOr<FieldReadResult<String>> read(
+  FutureOr<FieldReadResult<String>> read(RequestContext req,
       Map<String, dynamic> fields, Iterable<UploadedFile> files) {
     var value = fields[name] as String;
     if (trim) {
@@ -50,7 +50,7 @@ class BoolField extends Field<bool> {
       renderer.visitBoolField(this);
 
   @override
-  FutureOr<FieldReadResult<bool>> read(
+  FutureOr<FieldReadResult<bool>> read(RequestContext req,
       Map<String, dynamic> fields, Iterable<UploadedFile> files) {
     if (fields.containsKey(name)) {
       return FieldReadResult.success(true);
@@ -59,3 +59,106 @@ class BoolField extends Field<bool> {
     }
   }
 }
+
+/// A [Field] that parses its value as a [num].
+class NumField<T extends num> extends Field<T> {
+  // Reuse text validation logic.
+  TextField _textField;
+
+  /// The minimum/maximum value for the field.
+  final T min, max;
+
+  /// The amount for a form field to increment by.
+  final num step;
+
+  NumField(String name,
+      {String label, bool isRequired = true, this.max, this.min, this.step})
+      : super(name, label: label, isRequired: isRequired) {
+    _textField = TextField(name, label: label, isRequired: isRequired);
+  }
+
+  @override
+  FutureOr<U> accept<U>(FormRenderer<U> renderer) =>
+      renderer.visitNumField(this);
+
+  @override
+  Future<FieldReadResult<T>> read(RequestContext req,
+      Map<String, dynamic> fields, Iterable<UploadedFile> files) async {
+    var result = await _textField.read(req, fields, files);
+    if (result == null) {
+      return null;
+    } else if (result.isSuccess != true) {
+      return FieldReadResult.failure(result.errors);
+    } else {
+      var value = num.tryParse(result.value);
+      if (value != null) {
+        if (min != null && value < min) {
+          return FieldReadResult.failure(['"$name" can be no less than $min.']);
+        } else if (max != null && value > max) {
+          return FieldReadResult.failure(
+              ['"$name" can be no greater than $max.']);
+        } else {
+          return FieldReadResult.success(value as T);
+        }
+      } else {
+        return FieldReadResult.failure(['"$name" must be a number.']);
+      }
+    }
+  }
+}
+
+/// A [NumField] that coerces its value to a [double].
+class DoubleField extends NumField<double> {
+  DoubleField(String name,
+      {String label, bool isRequired = true, num step, double min, double max})
+      : super(name,
+            label: label,
+            isRequired: isRequired,
+            step: step,
+            min: min,
+            max: max);
+
+  @override
+  Future<FieldReadResult<double>> read(RequestContext req,
+      Map<String, dynamic> fields, Iterable<UploadedFile> files) async {
+    var result = await super.read(req, fields, files);
+    if (result == null) {
+      return null;
+    } else if (!result.isSuccess) {
+      return FieldReadResult.failure(result.errors);
+    } else {
+      return FieldReadResult.success(result.value.toDouble());
+    }
+  }
+}
+
+/// A [NumField] that requires its value to be an [int].
+/// Passing a [double] will result in an error, so [step] defaults to 1.
+class IntField extends NumField<int> {
+  IntField(String name,
+      {String label, bool isRequired = true, num step = 1, int min, int max})
+      : super(name,
+            label: label,
+            isRequired: isRequired,
+            step: step,
+            min: min,
+            max: max);
+
+  @override
+  Future<FieldReadResult<int>> read(RequestContext req,
+      Map<String, dynamic> fields, Iterable<UploadedFile> files) async {
+    var result = await super.read(req, fields, files);
+    if (result == null) {
+      return null;
+    } else if (!result.isSuccess) {
+      return FieldReadResult.failure(result.errors);
+    } else {
+      var value = result.value;
+      if (value is int) {
+        return FieldReadResult.success(result.value);
+      } else {
+        return FieldReadResult.failure(['"$name" must be an integer.']);
+      }
+    }
+  }
+}

lib/src/field.dart

@@ -44,7 +44,7 @@ abstract class Field<T> {
   ///
   /// If it returns `null` and [isRequired] is `true`, an error must
   /// be generated.
-  FutureOr<FieldReadResult<T>> read(
+  FutureOr<FieldReadResult<T>> read(RequestContext req,
       Map<String, dynamic> fields, Iterable<UploadedFile> files);
 
   /// Accepts a form renderer.
@@ -69,8 +69,8 @@ abstract class Field<T> {
       await req.parseBody();
       uploadedFiles = req.uploadedFiles;
     }
-    var result =
+    var result = await read(
-        await read(query ? req.queryParameters : req.bodyAsMap, uploadedFiles);
+        req, query ? req.queryParameters : req.bodyAsMap, uploadedFiles);
     if (result?.isSuccess != true && defaultValue != null) {
       return defaultValue;
     } else if (result == null) {
@@ -99,9 +99,9 @@ class _MatchedField<T> extends Field<T> {
   FutureOr<U> accept<U>(FormRenderer<U> renderer) => inner.accept(renderer);
 
   @override
-  Future<FieldReadResult<T>> read(
+  Future<FieldReadResult<T>> read(RequestContext req,
       Map<String, dynamic> fields, Iterable<UploadedFile> files) async {
-    var result = await inner.read(fields, files);
+    var result = await inner.read(req, fields, files);
     if (!result.isSuccess) {
       return result;
     } else {

lib/src/form.dart

@@ -109,7 +109,7 @@ class Form {
 
     for (var field in fields) {
       var result = await field.read(
-          query ? req.queryParameters : req.bodyAsMap, uploadedFiles);
+          req, query ? req.queryParameters : req.bodyAsMap, uploadedFiles);
       if (result == null && field.isRequired) {
         errors.add(reportMissingField(field.name, query: query));
       } else if (!result.isSuccess) {

lib/src/form_renderer.dart

@@ -9,5 +9,7 @@ abstract class FormRenderer<T> {
 
   FutureOr<T> visitBoolField(BoolField field);
 
+  FutureOr<T> visitNumField(NumField field);
+
   FutureOr<T> visitTextField(TextField field);
 }

test/all_test.dart

@@ -0,0 +1,4 @@
+import 'package:angel_validate/angel_validate.dart';
+import 'package:test/test.dart';
+
+void main() {}