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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.
using Microsoft.AspNetCore.Mvc.Core;
using Microsoft.AspNetCore.Mvc.ModelBinding;
namespace Microsoft.AspNetCore.Mvc;
/// <summary>
/// An attribute that can specify a model name or type of <see cref="IModelBinder"/> to use for binding.
/// </summary>
[AttributeUsage(
// Support method parameters in actions.
AttributeTargets.Parameter |
// Support properties on model DTOs.
AttributeTargets.Property |
// Support model types.
AttributeTargets.Class |
AttributeTargets.Enum |
AttributeTargets.Struct,
AllowMultiple = false,
Inherited = true)]
public class ModelBinderAttribute : Attribute, IModelNameProvider, IBinderTypeProviderMetadata
{
private BindingSource? _bindingSource;
private Type? _binderType;
/// <summary>
/// Initializes a new instance of <see cref="ModelBinderAttribute"/>.
/// </summary>
public ModelBinderAttribute()
{
}
/// <summary>
/// Initializes a new instance of <see cref="ModelBinderAttribute"/>.
/// </summary>
/// <param name="binderType">A <see cref="Type"/> which implements <see cref="IModelBinder"/>.</param>
/// <remarks>
/// Subclass this attribute and set <see cref="BindingSource"/> if <see cref="BindingSource.Custom"/> is not
/// correct for the specified <paramref name="binderType"/>.
/// </remarks>
public ModelBinderAttribute(Type binderType)
{
ArgumentNullException.ThrowIfNull(binderType);
BinderType = binderType;
}
/// <inheritdoc />
/// <remarks>
/// Subclass this attribute and set <see cref="BindingSource"/> if <see cref="BindingSource.Custom"/> is not
/// correct for the specified (non-<see langword="null"/>) <see cref="IModelBinder"/> implementation.
/// </remarks>
public Type? BinderType
{
get => _binderType;
set
{
if (value != null && !typeof(IModelBinder).IsAssignableFrom(value))
{
throw new ArgumentException(
Resources.FormatBinderType_MustBeIModelBinder(
value.FullName,
typeof(IModelBinder).FullName),
nameof(value));
}
_binderType = value;
}
}
/// <inheritdoc />
/// <value>
/// If <see cref="BinderType"/> is <see langword="null"/>, defaults to <see langword="null"/>. Otherwise,
/// defaults to <see cref="BindingSource.Custom"/>. May be overridden in a subclass.
/// </value>
public virtual BindingSource? BindingSource
{
get
{
if (_bindingSource == null && BinderType != null)
{
return BindingSource.Custom;
}
return _bindingSource;
}
protected set
{
_bindingSource = value;
}
}
/// <inheritdoc />
public string? Name { get; set; }
}
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