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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.Http;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
namespace Microsoft.AspNetCore.Mvc.ModelBinding;
/// <summary>
/// A context that contains operating information for model binding and validation.
/// </summary>
public abstract class ModelBindingContext
{
/// <summary>
/// Represents the <see cref="Mvc.ActionContext"/> associated with this context.
/// </summary>
/// <remarks>
/// The property setter is provided for unit testing purposes only.
/// </remarks>
public abstract ActionContext ActionContext { get; set; }
/// <summary>
/// Gets or sets a model name which is explicitly set using an <see cref="IModelNameProvider"/>.
/// </summary>
public abstract string? BinderModelName { get; set; }
/// <summary>
/// Gets or sets a value which represents the <see cref="ModelBinding.BindingSource"/> associated with the
/// <see cref="Model"/>.
/// </summary>
public abstract BindingSource? BindingSource { get; set; }
/// <summary>
/// Gets or sets the name of the current field being bound.
/// </summary>
public abstract string FieldName { get; set; }
/// <summary>
/// Gets the <see cref="Http.HttpContext"/> associated with this context.
/// </summary>
public virtual HttpContext HttpContext => ActionContext?.HttpContext!;
/// <summary>
/// Gets or sets an indication that the current binder is handling the top-level object.
/// </summary>
/// <remarks>Passed into the model binding system.</remarks>
public abstract bool IsTopLevelObject { get; set; }
/// <summary>
/// Gets or sets the model value for the current operation.
/// </summary>
/// <remarks>
/// The <see cref="Model"/> will typically be set for a binding operation that works
/// against a pre-existing model object to update certain properties.
/// </remarks>
public abstract object? Model { get; set; }
/// <summary>
/// Gets or sets the metadata for the model associated with this context.
/// </summary>
public abstract ModelMetadata ModelMetadata { get; set; }
/// <summary>
/// Gets or sets the name of the model. This property is used as a key for looking up values in
/// <see cref="IValueProvider"/> during model binding.
/// </summary>
public abstract string ModelName { get; set; }
/// <summary>
/// Gets or sets the name of the top-level model. This is not reset to <see cref="string.Empty"/> when value
/// providers have no match for that model.
/// </summary>
public string OriginalModelName { get; protected set; } = default!;
/// <summary>
/// Gets or sets the <see cref="ModelStateDictionary"/> used to capture <see cref="ModelStateEntry"/> values
/// for properties in the object graph of the model when binding.
/// </summary>
/// <remarks>
/// The property setter is provided for unit testing purposes only.
/// </remarks>
public abstract ModelStateDictionary ModelState { get; set; }
/// <summary>
/// Gets the type of the model.
/// </summary>
/// <remarks>
/// The <see cref="ModelMetadata"/> property must be set to access this property.
/// </remarks>
public virtual Type ModelType => ModelMetadata.ModelType;
/// <summary>
/// Gets or sets a predicate which will be evaluated for each property to determine if the property
/// is eligible for model binding.
/// </summary>
public abstract Func<ModelMetadata, bool>? PropertyFilter { get; set; }
/// <summary>
/// Gets or sets the <see cref="ValidationStateDictionary"/>. Used for tracking validation state to
/// customize validation behavior for a model object.
/// </summary>
/// <remarks>
/// The property setter is provided for unit testing purposes only.
/// </remarks>
public abstract ValidationStateDictionary ValidationState { get; set; }
/// <summary>
/// Gets or sets the <see cref="IValueProvider"/> associated with this context.
/// </summary>
public abstract IValueProvider ValueProvider { get; set; }
/// <summary>
/// <para>
/// Gets or sets a <see cref="ModelBindingResult"/> which represents the result of the model binding process.
/// </para>
/// <para>
/// Before an <see cref="IModelBinder"/> is called, <see cref="Result"/> will be set to a value indicating
/// failure. The binder should set <see cref="Result"/> to a value created with
/// <see cref="ModelBindingResult.Success"/> if model binding succeeded.
/// </para>
/// </summary>
public abstract ModelBindingResult Result { get; set; }
/// <summary>
/// Pushes a layer of state onto this context. <see cref="IModelBinder"/> implementations will call this as
/// part of recursion when binding properties or collection items.
/// </summary>
/// <param name="modelMetadata">
/// <see cref="ModelBinding.ModelMetadata"/> to assign to the <see cref="ModelMetadata"/> property.
/// </param>
/// <param name="fieldName">Name to assign to the <see cref="FieldName"/> property.</param>
/// <param name="modelName">Name to assign to the <see cref="ModelName"/> property.</param>
/// <param name="model">Instance to assign to the <see cref="Model"/> property.</param>
/// <returns>
/// A <see cref="NestedScope"/> scope object which should be used in a <c>using</c> statement where
/// <see cref="EnterNestedScope(ModelMetadata, string, string, object)"/> is called.
/// </returns>
public abstract NestedScope EnterNestedScope(
ModelMetadata modelMetadata,
string fieldName,
string modelName,
object? model);
/// <summary>
/// Pushes a layer of state onto this context. <see cref="IModelBinder"/> implementations will call this as
/// part of recursion when binding properties or collection items.
/// </summary>
/// <returns>
/// A <see cref="NestedScope"/> scope object which should be used in a <c>using</c> statement where
/// <see cref="EnterNestedScope()"/> is called.
/// </returns>
public abstract NestedScope EnterNestedScope();
/// <summary>
/// Removes a layer of state pushed by calling <see cref="M:EnterNestedScope"/>.
/// </summary>
protected abstract void ExitNestedScope();
/// <summary>
/// Return value of <see cref="M:EnterNestedScope"/>. Should be disposed
/// by caller when child binding context state should be popped off of
/// the <see cref="ModelBindingContext"/>.
/// </summary>
public readonly struct NestedScope : IDisposable
{
private readonly ModelBindingContext _context;
/// <summary>
/// Initializes the <see cref="NestedScope"/> for a <see cref="ModelBindingContext"/>.
/// </summary>
/// <param name="context"></param>
public NestedScope(ModelBindingContext context)
{
_context = context;
}
/// <summary>
/// Exits the <see cref="NestedScope"/> created by calling <see cref="M:EnterNestedScope"/>.
/// </summary>
public void Dispose()
{
_context.ExitNestedScope();
}
}
}
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