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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
#nullable enable
using System.Globalization;
using System.Runtime.ExceptionServices;
using Microsoft.Extensions.Logging;
namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders;
/// <summary>
/// An <see cref="IModelBinder"/> for <see cref="float"/> and <see cref="Nullable{T}"/> where <c>T</c> is
/// <see cref="float"/>.
/// </summary>
public class FloatModelBinder : IModelBinder
{
private readonly NumberStyles _supportedStyles;
private readonly ILogger _logger;
/// <summary>
/// Initializes a new instance of <see cref="FloatModelBinder"/>.
/// </summary>
/// <param name="supportedStyles">The <see cref="NumberStyles"/>.</param>
/// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
public FloatModelBinder(NumberStyles supportedStyles, ILoggerFactory loggerFactory)
{
ArgumentNullException.ThrowIfNull(loggerFactory);
_supportedStyles = supportedStyles;
_logger = loggerFactory.CreateLogger(typeof(FloatModelBinder));
}
/// <inheritdoc />
public Task BindModelAsync(ModelBindingContext bindingContext)
{
ArgumentNullException.ThrowIfNull(bindingContext);
_logger.AttemptingToBindModel(bindingContext);
var modelName = bindingContext.ModelName;
var valueProviderResult = bindingContext.ValueProvider.GetValue(modelName);
if (valueProviderResult == ValueProviderResult.None)
{
_logger.FoundNoValueInRequest(bindingContext);
// no entry
_logger.DoneAttemptingToBindModel(bindingContext);
return Task.CompletedTask;
}
var modelState = bindingContext.ModelState;
modelState.SetModelValue(modelName, valueProviderResult);
var metadata = bindingContext.ModelMetadata;
var type = metadata.UnderlyingOrModelType;
try
{
var value = valueProviderResult.FirstValue;
object? model;
if (string.IsNullOrWhiteSpace(value))
{
// Parse() method trims the value (with common NumberStyles) then throws if the result is empty.
model = null;
}
else if (type == typeof(float))
{
model = float.Parse(value, _supportedStyles, valueProviderResult.Culture);
}
else
{
// unreachable
throw new NotSupportedException();
}
// When converting value, a null model may indicate a failed conversion for an otherwise required
// model (can't set a ValueType to null). This detects if a null model value is acceptable given the
// current bindingContext. If not, an error is logged.
if (model == null && !metadata.IsReferenceOrNullableType)
{
modelState.TryAddModelError(
modelName,
metadata.ModelBindingMessageProvider.ValueMustNotBeNullAccessor(
valueProviderResult.ToString()));
}
else
{
bindingContext.Result = ModelBindingResult.Success(model);
}
}
catch (Exception exception)
{
var isFormatException = exception is FormatException;
if (!isFormatException && exception.InnerException != null)
{
// Unlike TypeConverters, floating point types do not seem to wrap FormatExceptions. Preserve
// this code in case a cursory review of the CoreFx code missed something.
exception = ExceptionDispatchInfo.Capture(exception.InnerException).SourceException;
}
modelState.TryAddModelError(modelName, exception, metadata);
// Conversion failed.
}
_logger.DoneAttemptingToBindModel(bindingContext);
return Task.CompletedTask;
}
}
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