Add Label TagHelper.

- Validated label TagHelper functionality. #1249
2014-10-14 15:13:20 -07:00 · 2014-10-14 15:13:20 -07:00 · f8b0249918
parent 9c07055ac7
commit f8b0249918
2 changed files with 256 additions and 0 deletions
--- a/src/Microsoft.AspNet.Mvc.TagHelpers/LabelTagHelper.cs
+++ b/src/Microsoft.AspNet.Mvc.TagHelpers/LabelTagHelper.cs
@ -0,0 +1,57 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Razor.Runtime.TagHelpers;
+using Microsoft.AspNet.Razor.TagHelpers;
+
+namespace Microsoft.AspNet.Mvc.TagHelpers
+{
+    /// <summary>
+    /// <see cref="ITagHelper"/> implementation targeting &lt;label&gt; elements with <c>for</c> attributes.
+    /// </summary>
+    [ContentBehavior(ContentBehavior.Modify)]
+    public class LabelTagHelper : TagHelper
+    {
+        // Protected to ensure subclasses are correctly activated. Internal for ease of use when testing.
+        [Activate]
+        protected internal ViewContext ViewContext { get; set; }
+
+        // Protected to ensure subclasses are correctly activated. Internal for ease of use when testing.
+        [Activate]
+        protected internal IHtmlGenerator Generator { get; set; }
+
+        /// <summary>
+        /// An expression to be evaluated against the current model.
+        /// </summary>
+        public ModelExpression For { get; set; }
+
+        /// <inheritdoc />
+        public override void Process(TagHelperContext context, TagHelperOutput output)
+        {
+            if (For != null)
+            {
+                var tagBuilder = Generator.GenerateLabel(ViewContext,
+                                                         For.Metadata,
+                                                         For.Name,
+                                                         labelText: null,
+                                                         htmlAttributes: null);
+
+                if (tagBuilder != null)
+                {
+                    output.MergeAttributes(tagBuilder);
+
+                    // We check for whitespace to detect scenarios such as:
+                    // <label for="Name">
+                    // </label>
+                    if (string.IsNullOrWhiteSpace(output.Content))
+                    {
+                        output.Content = tagBuilder.InnerHtml;
+                    }
+
+                    output.TagName = tagBuilder.TagName;
+                }
+            }
+        }
+    }
+}
--- a/test/Microsoft.AspNet.Mvc.TagHelpers.Test/LabelTagHelperTest.cs
+++ b/test/Microsoft.AspNet.Mvc.TagHelpers.Test/LabelTagHelperTest.cs
@ -0,0 +1,199 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.AspNet.Mvc.Razor;
+using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Razor.Runtime.TagHelpers;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.TagHelpers
+{
+    public class LabelTagHelperTest
+    {
+        // Model (List<Model> or Model instance), container type (Model or NestModel), model accessor,
+        // property path, TagHelperOutput.Content values.
+        public static TheoryData<object, Type, Func<object>, string, TagHelperOutputContent> TestDataSet
+        {
+            get
+            {
+                var modelWithNull = new Model
+                {
+                    NestedModel = new NestedModel
+                    {
+                        Text = null,
+                    },
+                    Text = null,
+                };
+                var modelWithText = new Model
+                {
+                    NestedModel = new NestedModel
+                    {
+                        Text = "inner text",
+                    },
+                    Text = "outer text",
+                };
+                var models = new List<Model>
+                {
+                    modelWithNull,
+                    modelWithText,
+                };
+
+                return new TheoryData<object, Type, Func<object>, string, TagHelperOutputContent>
+                {
+                    { null, typeof(Model), () => null, "Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+
+                    { modelWithNull, typeof(Model), () => modelWithNull.Text, "Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { modelWithText, typeof(Model), () => modelWithText.Text, "Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { modelWithText, typeof(Model), () => modelWithNull.Text, "Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+                    { modelWithText, typeof(Model), () => modelWithText.Text, "Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+
+                    { modelWithNull, typeof(NestedModel), () => modelWithNull.NestedModel.Text, "NestedModel.Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { modelWithText, typeof(NestedModel), () => modelWithText.NestedModel.Text, "NestedModel.Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { modelWithNull, typeof(NestedModel), () => modelWithNull.NestedModel.Text, "NestedModel.Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+                    { modelWithText, typeof(NestedModel), () => modelWithText.NestedModel.Text, "NestedModel.Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+
+                    // Note: Tests cases below here will not work in practice due to current limitations on indexing 
+                    // into ModelExpressions. Will be fixed in https://github.com/aspnet/Mvc/issues/1345.
+                    { models, typeof(Model), () => models[0].Text, "[0].Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { models, typeof(Model), () => models[1].Text, "[1].Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { models, typeof(Model), () => models[0].Text, "[0].Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+                    { models, typeof(Model), () => models[1].Text, "[1].Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+
+                    { models, typeof(NestedModel), () => models[0].NestedModel.Text, "[0].NestedModel.Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { models, typeof(NestedModel), () => models[1].NestedModel.Text, "[1].NestedModel.Text",
+                        new TagHelperOutputContent(Environment.NewLine, "Text") },
+                    { models, typeof(NestedModel), () => models[0].NestedModel.Text, "[0].NestedModel.Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+                    { models, typeof(NestedModel), () => models[1].NestedModel.Text, "[1].NestedModel.Text",
+                        new TagHelperOutputContent("Hello World", "Hello World") },
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(TestDataSet))]
+        public async Task ProcessAsync_GeneratesExpectedOutput(
+            object model,
+            Type containerType,
+            Func<object> modelAccessor,
+            string propertyPath,
+            TagHelperOutputContent tagHelperOutputContent)
+        {
+            // Arrange
+            var expectedAttributes = new Dictionary<string, string>
+            {
+                { "class", "form-control" },
+                { "for", propertyPath }
+            };
+            var metadataProvider = new DataAnnotationsModelMetadataProvider();
+
+            // Property name is either nameof(Model.Text) or nameof(NestedModel.Text).
+            var metadata = metadataProvider.GetMetadataForProperty(modelAccessor, containerType, propertyName: "Text");
+            var modelExpression = new ModelExpression(propertyPath, metadata);
+            var tagHelper = new LabelTagHelper
+            {
+                For = modelExpression,
+            };
+
+            var tagHelperContext = new TagHelperContext(allAttributes: new Dictionary<string, object>());
+            var htmlAttributes = new Dictionary<string, string>
+            {
+                { "class", "form-control" },
+            };
+            var output = new TagHelperOutput("A random tag name", htmlAttributes, tagHelperOutputContent.OriginalContent);
+            var expectedTagName = "label";
+            var htmlGenerator = new TestableHtmlGenerator(metadataProvider);
+            var viewContext = TestableHtmlGenerator.GetViewContext(model, htmlGenerator, metadataProvider);
+            tagHelper.ViewContext = viewContext;
+            tagHelper.Generator = htmlGenerator;
+
+            // Act
+            await tagHelper.ProcessAsync(tagHelperContext, output);
+
+            // Assert
+            Assert.Equal(expectedAttributes, output.Attributes);
+            Assert.Equal(tagHelperOutputContent.ExpectedContent, output.Content);
+            Assert.False(output.SelfClosing);
+            Assert.Equal(expectedTagName, output.TagName);
+        }
+
+        [Fact]
+        public async Task TagHelper_LeavesOutputUnchanged_IfForNotBound2()
+        {
+            // Arrange
+            var expectedAttributes = new Dictionary<string, string>
+            {
+                { "class", "form-control" },
+            };
+            var expectedContent = "original content";
+            var expectedTagName = "original tag name";
+
+            var metadataProvider = new DataAnnotationsModelMetadataProvider();
+            var metadata = metadataProvider.GetMetadataForProperty(
+                modelAccessor: () => null,
+                containerType: typeof(Model),
+                propertyName: nameof(Model.Text));
+            var modelExpression = new ModelExpression(nameof(Model.Text), metadata);
+            var tagHelper = new LabelTagHelper();
+
+            var tagHelperContext = new TagHelperContext(allAttributes: new Dictionary<string, object>());
+            var output = new TagHelperOutput(expectedTagName, expectedAttributes, expectedContent);
+
+            var htmlGenerator = new TestableHtmlGenerator(metadataProvider);
+            Model model = null;
+            var viewContext = TestableHtmlGenerator.GetViewContext(model, htmlGenerator, metadataProvider);
+            var activator = new DefaultTagHelperActivator();
+            activator.Activate(tagHelper, viewContext);
+
+            // Act
+            await tagHelper.ProcessAsync(tagHelperContext, output);
+
+            // Assert
+            Assert.Equal(expectedAttributes, output.Attributes);
+            Assert.Equal(expectedContent, output.Content);
+            Assert.Equal(expectedTagName, output.TagName);
+        }
+
+        public class TagHelperOutputContent
+        {
+            public TagHelperOutputContent(string outputContent, string expectedContent)
+            {
+                OriginalContent = outputContent;
+                ExpectedContent = expectedContent;
+            }
+
+            public string OriginalContent { get; set; }
+            public string ExpectedContent { get; set; }
+        }
+
+        private class Model
+        {
+            public string Text { get; set; }
+
+            public NestedModel NestedModel { get; set; }
+        }
+
+        private class NestedModel
+        {
+            public string Text { get; set; }
+        }
+    }
+}