[英]Custom Model Binding in Asp .Net Core
我正在嘗試將具有IFormFile或IFormFileCollection屬性的模型綁定到我的自定義類CommonFile 。 我沒有在互聯網上找到這么多關於它使用asp .net核心的文檔,我試圖在ASP.Net Core 1.0中關注此鏈接自定義模型綁定,但它綁定了一個SimpleType屬性,我需要綁定一個復雜的類型。 無論如何,我試圖使我的這個綁定版本,我有以下代碼:
FormFileModelBinderProvider.cs
public class FormFileModelBinderProvider : IModelBinderProvider
{
public IModelBinder GetBinder(ModelBinderProviderContext context)
{
if (context == null) throw new ArgumentNullException(nameof(context));
if (!context.Metadata.IsComplexType) return null;
var isIEnumerableFormFiles = context.Metadata.ModelType.GetInterfaces().Contains(typeof(IEnumerable<CommonFile>));
var isFormFile = context.Metadata.ModelType.IsAssignableFrom(typeof(CommonFile));
if (!isFormFile && !isIEnumerableFormFiles) return null;
var propertyBinders = context.Metadata.Properties.ToDictionary(property => property,
context.CreateBinder);
return new FormFileModelBinder(propertyBinders);
}
}
FromFileModelBinder.cs
以下代碼不完整,因為我沒有使用bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
得到任何結果bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
雖然我正在調試一切順利,直到bindingContext.ModelName沒有值,我無法綁定我的模型從httpContext到強類型模型。
public class FormFileModelBinder : IModelBinder
{
private readonly ComplexTypeModelBinder _baseBinder;
public FormFileModelBinder(IDictionary<ModelMetadata, IModelBinder> propertyBinders)
{
_baseBinder = new ComplexTypeModelBinder(propertyBinders);
}
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null) throw new ArgumentNullException(nameof(bindingContext));
var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
return Task.CompletedTask;
}
}
有什么建議么?
10個月后,我找到了一個我想做的解決方案。
總結:我想用我自己的沒有附加到Asp .Net的類替換IFormFile IFormFileCollection,因為我的視圖模型與poco類在不同的項目中。 我的自定義類是ICommonFile,ICommonFileCollection,IFormFile(不是Asp .net核心類)和IFormFileCollection。
我將在這里分享:
ICommonFile.cs
/// <summary>
/// File with common Parameters including bytes
/// </summary>
public interface ICommonFile
{
/// <summary>
/// Stream File
/// </summary>
Stream File { get; }
/// <summary>
/// Name of the file
/// </summary>
string Name { get; }
/// <summary>
/// Gets the file name with extension.
/// </summary>
string FileName { get; }
/// <summary>
/// Gets the file length in bytes.
/// </summary>
long Length { get; }
/// <summary>
/// Copies the contents of the uploaded file to the <paramref name="target"/> stream.
/// </summary>
/// <param name="target">The stream to copy the file contents to.</param>
void CopyTo(Stream target);
/// <summary>
/// Asynchronously copies the contents of the uploaded file to the <paramref name="target"/> stream.
/// </summary>
/// <param name="target">The stream to copy the file contents to.</param>
/// <param name="cancellationToken">Enables cooperative cancellation between threads</param>
Task CopyToAsync(Stream target, CancellationToken cancellationToken = default(CancellationToken));
}
ICommonFileCollection.cs
/// <inheritdoc />
/// <summary>
/// Represents the collection of files.
/// </summary>
public interface ICommonFileCollection : IReadOnlyList<ICommonFile>
{
/// <summary>
/// File Indexer by name
/// </summary>
/// <param name="name">File name index</param>
/// <returns>File with related file name index</returns>
ICommonFile this[string name] { get; }
/// <summary>
/// Gets file by name
/// </summary>
/// <param name="name">file name</param>
/// <returns>File with related file name index</returns>
ICommonFile GetFile(string name);
/// <summary>
/// Gets Files by name
/// </summary>
/// <param name="name"></param>>
/// <returns>Files with related file name index</returns>
IReadOnlyList<ICommonFile> GetFiles(string name);
}
IFormFile.cs
/// <inheritdoc />
/// <summary>
/// File transferred by HttpProtocol, this is an independent
/// Asp.net core interface
/// </summary>
public interface IFormFile : ICommonFile
{
/// <summary>
/// Gets the raw Content-Type header of the uploaded file.
/// </summary>
string ContentType { get; }
/// <summary>
/// Gets the raw Content-Disposition header of the uploaded file.
/// </summary>
string ContentDisposition { get; }
}
IFormFileCollection.cs
/// <summary>
/// File Collection transferred by HttpProtocol, this is an independent
/// Asp.net core implementation
/// </summary>
public interface IFormFileCollection
{
//Use it when you need to implement new features to Form File collection over HttpProtocol
}
我終於成功創建了我的模型綁定器,我也將分享它:
FormFileModelBinderProvider.cs
/// <inheritdoc />
/// <summary>
/// Model Binder Provider, it inspects
/// any model when the request is triggered
/// </summary>
public class FormFileModelBinderProvider : IModelBinderProvider
{
/// <inheritdoc />
/// <summary>
/// Inspects a Model for any CommonFile class or Collection with
/// same class if exist the FormFileModelBinder initiates
/// </summary>
/// <param name="context">Model provider context</param>
/// <returns>a new Instance o FormFileModelBinder if type is found otherwise null</returns>
public IModelBinder GetBinder(ModelBinderProviderContext context)
{
if (context == null) throw new ArgumentNullException(nameof(context));
if (!context.Metadata.IsComplexType) return null;
var isSingleCommonFile = IsSingleCommonFile(context.Metadata.ModelType);
var isCommonFileCollection = IsCommonFileCollection(context.Metadata.ModelType);
if (!isSingleCommonFile && !isCommonFileCollection) return null;
return new FormFileModelBinder();
}
/// <summary>
/// Checks if object type is a CommonFile Collection
/// </summary>
/// <param name="modelType">Context Meta data ModelType</param>
/// <returns>If modelType is a collection of CommonFile returns true otherwise false</returns>
private static bool IsCommonFileCollection(Type modelType)
{
if (typeof(ICommonFileCollection).IsAssignableFrom(modelType))
{
return true;
}
var hasCommonFileArguments = modelType.GetGenericArguments()
.AsParallel().Any(t => typeof(ICommonFile).IsAssignableFrom(t));
if (typeof(IEnumerable).IsAssignableFrom(modelType) && hasCommonFileArguments)
{
return true;
}
if (typeof(IAsyncEnumerable<object>).IsAssignableFrom(modelType) && hasCommonFileArguments)
{
return true;
}
return false;
}
/// <summary>
/// Checks if object type is CommonFile or an implementation of ICommonFile
/// </summary>
/// <param name="modelType"></param>
/// <returns></returns>
private static bool IsSingleCommonFile(Type modelType)
{
if (modelType == typeof(ICommonFile) || modelType.GetInterfaces().Contains(typeof(ICommonFile)))
{
return true;
}
return false;
}
}
FormFileModelBinder.cs
/// <inheritdoc />
/// <summary>
/// Form File Model binder
/// Parses the Form file object type to a commonFile
/// </summary>
public class FormFileModelBinder : IModelBinder
{
/// <summary>
/// Expression to map IFormFile object type to CommonFile
/// </summary>
private readonly Func<Microsoft.AspNetCore.Http.IFormFile, ICommonFile> _expression;
/// <summary>
/// FormFile Model binder constructor
/// </summary>
public FormFileModelBinder()
{
_expression = x => new CommonFile(x.OpenReadStream(), x.Length, x.Name, x.FileName);
}
/// <inheritdoc />
/// <summary>
/// It Binds IFormFile to Common file, getting the file
/// from the binding context
/// </summary>
/// <param name="bindingContext">Http Context</param>
/// <returns>Completed Task</returns>
// TODO: Bind this context to ICommonFile or ICommonFileCollection object
public Task BindModelAsync(ModelBindingContext bindingContext)
{
dynamic model;
if (bindingContext == null) throw new ArgumentNullException(nameof(bindingContext));
var formFiles = bindingContext.ActionContext.HttpContext.Request.Form.Files;
if (!formFiles.Any()) return Task.CompletedTask;
if (formFiles.Count > 1)
{
model = formFiles.AsParallel().Select(_expression);
}
else
{
model = new FormFileCollection();
model.AddRange(filteredFiles.AsParallel().Select(_expression));
}
bindingContext.Result = ModelBindingResult.Success(model);
return Task.CompletedTask;
}
}
實際上一切都很好,除非我有嵌套模型。 我分享了我正在使用的模型的一個例子,我將對工作場景做一些評論,而不是Test.cs
public class Test
{
//It's Working
public ICommonFileCollection Files { get; set; }
//It's Working
public ICommonFileCollection Files2 { get; set; }
//This is a nested model
public TestExtra TestExtra { get; set; }
}
TestExtra.cs
public class TestExtra
{
//It's not working
public ICommonFileCollection Files { get; set; }
}
實際上,當我向我的API發出請求時,我得到了以下內容(截圖):
如果有任何服從使用嵌套模型的工作,那就太棒了。
更新 Asp Net Core Model Binder不會僅僅使用一個屬性綁定模型,如果類中有一個屬性,該屬性將為null但是當您添加兩個或更多屬性時將綁定它。 我的錯誤我在嵌套類中有一個屬性。 整個代碼都是正確的。
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