Adding Enum support from QueryStrings

Source/Prism.Tests/Common/Mocks/MockEnum.cs

@@ -0,0 +1,11 @@
+namespace Prism.Tests.Common.Mocks
+{
+    internal enum MockEnum
+    {
+        None = 0,
+        Foo = 1,
+        Bar = 2,
+        Fizz = 3,
+        SomethingElse = 99
+    }
+}

Source/Prism.Tests/Common/Mocks/MockParameters.cs

@@ -0,0 +1,10 @@
+using Prism.Common;
+
+namespace Prism.Tests.Common.Mocks
+{
+    internal class MockParameters : ParametersBase
+    {
+        public MockParameters() : base() { }
+        public MockParameters(string query) : base(query) { }
+    }
+}

Source/Prism.Tests/Common/ParametersFixture.cs

@@ -0,0 +1,56 @@
+using System.Collections.Generic;
+using System.Linq;
+using Prism.Tests.Common.Mocks;
+using Xunit;
+
+namespace Prism.Tests.Common
+{
+    public class ParametersFixture
+    {
+        [Fact]
+        public void TryGetValueOfT()
+        {
+            var parameters = new MockParameters("mock=Foo&mock2=1");
+            bool success = false;
+            MockEnum value = default;
+            MockEnum value1 = default;
+
+            var ex = Record.Exception(() => success = parameters.TryGetValue<MockEnum>("mock", out value));
+            var ex2 = Record.Exception(() => success = parameters.TryGetValue<MockEnum>("mock2", out value1));
+            Assert.Null(ex);
+            Assert.True(success);
+            Assert.Equal(MockEnum.Foo, value);
+            Assert.Equal(value, value1);
+        }
+
+        [Fact]
+        public void GetValuesOfT()
+        {
+            var parameters = new MockParameters("mock=Foo&mock=2&mock=Fizz");
+
+            IEnumerable<MockEnum> values = default;
+
+            var ex = Record.Exception(() => values = parameters.GetValues<MockEnum>("mock"));
+            Assert.Null(ex);
+            Assert.Equal(3, values.Count());
+            Assert.Equal(MockEnum.Foo, values.ElementAt(0));
+            Assert.Equal(MockEnum.Bar, values.ElementAt(1));
+            Assert.Equal(MockEnum.Fizz, values.ElementAt(2));
+        }
+
+
+        [Fact]
+        public void GetValue()
+        {
+            var parameters = new MockParameters("mock=Foo&mock1=2&mock2=Fizz");
+            MockEnum value = default;
+            MockEnum value1 = default;
+
+            var ex = Record.Exception(() => value = parameters.GetValue<MockEnum>("mock"));
+            var ex2 = Record.Exception(() => value1 = parameters.GetValue<MockEnum>("mock1"));
+            Assert.Null(ex);
+            Assert.Equal(MockEnum.Foo, value);
+            Assert.Equal(MockEnum.Bar, value1);
+        }
+    }
+}

Source/Prism/Common/ParametersExtensions.cs

@@ -19,14 +19,10 @@ public static object GetValue(this IEnumerable<KeyValuePair<string, object>> par
             {
                 if (string.Compare(kvp.Key, key, StringComparison.Ordinal) == 0)
                 {
-                    if (kvp.Value == null)
-                        return GetDefault(type);
-                    else if (kvp.Value.GetType() == type)
-                        return kvp.Value;
-                    else if (type.IsAssignableFrom(kvp.Value.GetType()))
-                        return kvp.Value;
-                    else
-                        return Convert.ChangeType(kvp.Value, type);
+                    if(TryGetValueInternal(kvp, type, out var value))
+                        return value;
+
+                    throw new InvalidCastException($"Unable to convert the value of Type '{kvp.Value.GetType().FullName}' to '{type.FullName}' for the key '{key}' ");
                 }
             }
 
@@ -36,20 +32,15 @@ public static object GetValue(this IEnumerable<KeyValuePair<string, object>> par
         [EditorBrowsable(EditorBrowsableState.Never)]
         public static bool TryGetValue<T>(this IEnumerable<KeyValuePair<string, object>> parameters, string key, out T value)
         {
+            var type = typeof(T);
+
             foreach (var kvp in parameters)
             {
                 if (string.Compare(kvp.Key, key, StringComparison.Ordinal) == 0)
                 {
-                    if (kvp.Value == null)
-                        value = default;
-                    else if (kvp.Value.GetType() == typeof(T))
-                        value = (T)kvp.Value;
-                    else if (typeof(T).IsAssignableFrom(kvp.Value.GetType()))
-                        value = (T)kvp.Value;
-                    else
-                        value = (T)Convert.ChangeType(kvp.Value, typeof(T));
-
-                    return true;
+                    var success = TryGetValueInternal(kvp, typeof(T), out object valueAsObject);
+                    value = (T)valueAsObject;
+                    return success;
                 }
             }
 
@@ -61,25 +52,62 @@ public static bool TryGetValue<T>(this IEnumerable<KeyValuePair<string, object>>
         public static IEnumerable<T> GetValues<T>(this IEnumerable<KeyValuePair<string, object>> parameters, string key)
         {
             List<T> values = new List<T>();
+            var type = typeof(T);
 
             foreach (var kvp in parameters)
             {
                 if (string.Compare(kvp.Key, key, StringComparison.Ordinal) == 0)
                 {
-                    if (kvp.Value == null)
-                        values.Add(default);
-                    else if (kvp.Value.GetType() == typeof(T))
-                        values.Add((T)kvp.Value);
-                    else if (typeof(T).IsAssignableFrom(kvp.Value.GetType()))
-                        values.Add((T)kvp.Value);
-                    else
-                        values.Add((T)Convert.ChangeType(kvp.Value, typeof(T)));
+                    TryGetValueInternal(kvp, type, out var value);
+                    values.Add((T)value);
                 }
             }
 
             return values.AsEnumerable();
         }
 
+        private static bool TryGetValueInternal(KeyValuePair<string, object> kvp, Type type, out object value)
+        {
+            value = GetDefault(type);
+            var success = false;
+            if (kvp.Value == null)
+            {
+                success = true;
+            }
+            else if (kvp.Value.GetType() == type)
+            {
+                success = true;
+                value = kvp.Value;
+            }
+            else if (type.IsAssignableFrom(kvp.Value.GetType()))
+            {
+                success = true;
+                value = kvp.Value;
+            }
+            else if (type.IsEnum)
+            {
+                var valueAsString = kvp.Value.ToString();
+                if (Enum.IsDefined(type, valueAsString))
+                {
+                    success = true;
+                    value = Enum.Parse(type, valueAsString);
+                }
+                else if (int.TryParse(valueAsString, out var numericValue))
+                {
+                    success = true;
+                    value = Enum.ToObject(type, numericValue);
+                }
+            }
+
+            if (!success && type.GetInterface("System.IConvertible") != null)
+            {
+                success = true;
+                value = Convert.ChangeType(kvp.Value, type);
+            }
+
+            return success;
+        }
+
         [EditorBrowsable(EditorBrowsableState.Never)]
         public static bool ContainsKey(this IEnumerable<KeyValuePair<string, object>> parameters, string key) =>
             parameters.Any(x => string.Compare(x.Key, key, StringComparison.Ordinal) == 0);

Source/Xamarin/Prism.Forms.Tests/Mvvm/AutoInitializeFixture.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Prism.Common;
+using Prism.Forms.Tests.Mvvm.Mocks.ViewModels;
+using Prism.Navigation;
+using Xunit;
+
+namespace Prism.Forms.Tests.Mvvm
+{
+    public class AutoInitializeFixture
+    {
+        [Fact]
+        public void ThrowsAnExceptionWithoutRequiredParameter()
+        {
+            var vm = new AutoInitializedViewModelMock();
+            var parameters = new NavigationParameters("?foo=bar");
+            var ex = Record.Exception(() => PageUtilities.Abracadabra(vm, parameters));
+
+            Assert.NotNull(ex);
+            Assert.IsType<ArgumentNullException>(ex);
+        }
+
+        [Fact]
+        public void NoExceptionWhenTitleIsProvided()
+        {
+            var vm = new AutoInitializedViewModelMock();
+            var parameters = new NavigationParameters("?success=true&title=Hello");
+            var ex = Record.Exception(() => PageUtilities.Abracadabra(vm, parameters));
+
+            Assert.Null(ex);
+            Assert.Equal("Hello", vm.Title);
+        }
+
+        [Fact]
+        public void SetsBooleanFromQueryString()
+        {
+            var vm = new AutoInitializedViewModelMock();
+            var parameters = new NavigationParameters("?success=true&title=Hello");
+            var ex = Record.Exception(() => PageUtilities.Abracadabra(vm, parameters));
+
+            Assert.Null(ex);
+            Assert.True(vm.Success);
+        }
+
+        [Fact]
+        public void SetsDateTimeFromQueryString()
+        {
+            var vm = new AutoInitializedViewModelMock();
+            var parameters = new NavigationParameters("?someDate=July 11, 2019 08:00&title=Hello");
+            var ex = Record.Exception(() => PageUtilities.Abracadabra(vm, parameters));
+
+            Assert.Null(ex);
+            var expected = new DateTime(2019, 7, 11, 8, 0, 0);
+            Assert.Equal(expected, vm.SomeDate);
+        }
+
+        [Theory]
+        [InlineData("status=OK", MockHttpStatus.OK)]
+        [InlineData("status=201", MockHttpStatus.Created)]
+        [InlineData("status=500", (MockHttpStatus)500)]
+        public void SetsEnumFromQueryString(string queryString, MockHttpStatus status)
+        {
+            var vm = new AutoInitializedViewModelMock();
+            var parameters = new NavigationParameters($"?{queryString}&title=Hello");
+            var ex = Record.Exception(() => PageUtilities.Abracadabra(vm, parameters));
+
+            Assert.Null(ex);
+            Assert.Equal(status, vm.Status);
+        }
+    }
+}

Source/Xamarin/Prism.Forms.Tests/Mvvm/Mocks/ViewModels/AutoInitializedViewModelMock.cs

@@ -0,0 +1,17 @@
+using System;
+using Prism.AppModel;
+
+namespace Prism.Forms.Tests.Mvvm.Mocks.ViewModels
+{
+    public class AutoInitializedViewModelMock : IAutoInitialize
+    {
+        [AutoInitialize(true)]
+        public string Title { get; set; }
+
+        public bool Success { get; set; }
+
+        public DateTime SomeDate { get; set; }
+
+        public MockHttpStatus Status { get; set; }
+    }
+}

Source/Xamarin/Prism.Forms.Tests/Mvvm/Mocks/ViewModels/MockHttpStatus.cs

@@ -0,0 +1,10 @@
+namespace Prism.Forms.Tests.Mvvm.Mocks.ViewModels
+{
+    public enum MockHttpStatus
+    {
+        Continue = 100,
+        OK = 200,
+        Created = 201,
+        MultipleChoices = 300
+    }
+}