/// <summary>
/// Called during Razor's code generation process to generate code that instantiates the value of the tag
/// helper's property. Last value written should not be or end with a semicolon.
/// </summary>
/// <param name="attributeDescriptor">
/// The <see cref="TagHelperAttributeDescriptor"/> to generate code for.
/// </param>
/// <param name="writer">The <see cref="CSharpCodeWriter"/> that's used to write code.</param>
/// <param name="context">A <see cref="Chunks.Generators.ChunkGeneratorContext"/> instance that contains
/// information about the current code generation process.</param>
/// <param name="renderAttributeValue">
/// <see cref="Action"/> that renders the raw value of the HTML attribute.
/// </param>
/// <param name="complexValue">
/// Indicates whether or not the source attribute value contains more than simple text. <c>false</c> for plain
/// C# expressions e.g. <c>"PropertyName"</c>. <c>true</c> if the attribute value contain at least one in-line
/// Razor construct e.g. <c>"@(@readonly)"</c>.
/// </param>
public virtual void RenderAttributeValue(
TagHelperAttributeDescriptor attributeDescriptor,
CSharpCodeWriter writer,
CodeGeneratorContext context,
Action<CSharpCodeWriter> renderAttributeValue,
bool complexValue)
{
if (attributeDescriptor == null)
{
throw new ArgumentNullException(nameof(attributeDescriptor));
}
if (writer == null)
{
throw new ArgumentNullException(nameof(writer));
}
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (renderAttributeValue == null)
{
throw new ArgumentNullException(nameof(renderAttributeValue));
}
renderAttributeValue(writer);
}
/// <inheritdoc />
/// <remarks>If the attribute being rendered is of the type
/// <see cref="GeneratedTagHelperAttributeContext.ModelExpressionTypeName"/>, then a model expression will be
/// created by calling into <see cref="GeneratedTagHelperAttributeContext.CreateModelExpressionMethodName"/>.
/// </remarks>
public override void RenderAttributeValue(
TagHelperAttributeDescriptor attributeDescriptor,
CSharpCodeWriter writer,
CodeGeneratorContext codeGeneratorContext,
Action<CSharpCodeWriter> renderAttributeValue,
bool complexValue)
{
if (attributeDescriptor == null)
{
throw new ArgumentNullException(nameof(attributeDescriptor));
}
if (writer == null)
{
throw new ArgumentNullException(nameof(writer));
}
if (codeGeneratorContext == null)
{
throw new ArgumentNullException(nameof(codeGeneratorContext));
}
if (renderAttributeValue == null)
{
throw new ArgumentNullException(nameof(renderAttributeValue));
}
if (attributeDescriptor.TypeName.Equals(_context.ModelExpressionTypeName, StringComparison.Ordinal))
{
writer
.WriteStartMethodInvocation(_context.CreateModelExpressionMethodName)
.Write(ModelLambdaVariableName)
.Write(" => ");
if (!complexValue)
{
writer
.Write(ModelLambdaVariableName)
.Write(".");
}
renderAttributeValue(writer);
writer.WriteEndMethodInvocation(endLine: false);
}
else
{
base.RenderAttributeValue(
attributeDescriptor,
writer,
codeGeneratorContext,
renderAttributeValue,
complexValue);
}
}
public void RenderAttributeValue_RendersModelExpressionsCorrectly(
string modelExpressionType,
string propertyType,
string expectedValue)
{
// Arrange
var renderer = new MvcTagHelperAttributeValueCodeRenderer(
new GeneratedTagHelperAttributeContext
{
ModelExpressionTypeName = modelExpressionType,
CreateModelExpressionMethodName = "SomeMethod"
});
var attributeDescriptor = new TagHelperAttributeDescriptor
{
Name = "MyAttribute",
PropertyName = "SomeProperty",
TypeName = propertyType,
};
var writer = new CSharpCodeWriter();
var generatorContext = new ChunkGeneratorContext(
host: null,
className: string.Empty,
rootNamespace: string.Empty,
sourceFile: string.Empty,
shouldGenerateLinePragmas: true);
var errorSink = new ErrorSink();
var context = new CodeGeneratorContext(generatorContext, errorSink);
// Act
renderer.RenderAttributeValue(attributeDescriptor, writer, context,
(codeWriter) =>
{
codeWriter.Write("MyValue");
},
complexValue: false);
// Assert
Assert.Equal(expectedValue, writer.GenerateCode());
}