Masuit.Tools/Masuit.Tools.AspNetCore/ModelBinder/ModelBindingContextExtension.cs

using System.Net.Mime;
using System.Text;
using Microsoft.AspNetCore.Mvc.Controllers;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.Extensions.Primitives;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace Masuit.Tools.AspNetCore.ModelBinder;

internal static class ModelBindingContextExtension
{
	/// <summary>
	/// 获取绑定参数对应的 Attribute
	/// </summary>
	/// <typeparam name="T">Attribute对象</typeparam>
	/// <param name="bindingContext">绑定参数上下文</param>
	/// <param name="parameterName">参数名称</param>
	/// <returns></returns>
	public static T GetAttribute<T>(this ModelBindingContext bindingContext, string parameterName = null) where T : Attribute
	{
		var fieldName = parameterName ?? bindingContext.FieldName;
		var ctrlActionDesc = bindingContext.ActionContext.ActionDescriptor as ControllerActionDescriptor;
		var fieldParameter = ctrlActionDesc!.MethodInfo.GetParameters().Single(p => p.Name == fieldName);
		return fieldParameter.GetCustomAttributes(typeof(T), false).Single() as T;
	}

	/// <summary>
	/// 判断该次请求体Body是否是Json内容类型
	/// </summary>
	/// <param name="httpContext"></param>
	/// <param name="charSet"></param>
	/// <returns></returns>
	public static bool IsJsonContent(this HttpContext httpContext, out string charSet)
	{
		string strContentType = httpContext.Request.ContentType;
		if (string.IsNullOrEmpty(strContentType))
		{
			charSet = null;
			return false;
		}

		var contentType = new ContentType(strContentType);
		charSet = contentType.CharSet;
		return contentType.MediaType.ToLower() == "application/json";
	}

	/// <summary>
	/// 获取请求体Body字符串内容
	/// </summary>
	/// <param name="context"></param>
	/// <param name="encoding"></param>
	/// <returns></returns>
	public static string GetBodyString(this HttpContext context, Encoding encoding)
	{
		context.Request.EnableBuffering(); //Ensure the HttpRequest.Body can be read multipletimes
		int contentLen = 255;
		if (context.Request.ContentLength != null)
		{
			contentLen = (int)context.Request.ContentLength;
		}

		var body = context.Request.Body;
		string bodyText;
		if (contentLen <= 0)
		{
			bodyText = "";
		}
		else
		{
			using var reader = new StreamReader(body, encoding, true, contentLen, true);
			bodyText = reader.ReadToEndAsync().Result;
		}

		body.Position = 0;
		return bodyText;
	}

	/// <summary>
	/// 尝试设置默认值
	/// </summary>
	/// <param name="bindingContext"></param>
	public static bool TrySetDefaultValue(this ModelBindingContext bindingContext)
	{
		var attr = bindingContext.GetAttribute<FromBodyOrDefaultAttribute>();
		if (attr.DefaultValue != null)
		{
			var targetValue = attr.DefaultValue.ChangeType(bindingContext.ModelType);
			bindingContext.Result = ModelBindingResult.Success(targetValue);
			return true;
		}

		return false;
	}

	/// <summary>
	/// 转换为对应类型
	/// </summary>
	/// <param name="this"></param>
	public static T ConvertObjectTo<T>(this object @this)
	{
		return (T)ConvertObject(@this, typeof(T));
	}

	/// <summary>
	/// 转换为对应类型
	/// </summary>
	/// <param name="this"></param>
	/// <param name="type"></param>
	public static object ConvertObject(this object @this, Type type)
	{
		object value;
		if (@this is string str)
		{
			str = str.Trim();
			if ((str.StartsWith("[") && str.EndsWith("]")) || str.StartsWith("{") && str.EndsWith("}"))
			{
				value = JsonConvert.DeserializeObject(str, type);
			}
			else if ((str.StartsWith("\"[") && str.EndsWith("]\"")) || str.StartsWith("\"{") && str.EndsWith("}\""))
			{
				// json字符串 又被 json序列化 的情况
				var objects = JsonConvert.DeserializeObject(str);
				value = JsonConvert.SerializeObject(objects).ConvertObject(type);
			}
			else
			{
				var text = JsonConvert.SerializeObject(@this);
				value = JsonConvert.DeserializeObject(text, type);
			}
		}
		else if (@this is StringValues values)
		{
			var text = values.ToString();
			if (type.IsSimpleArrayType() || type.IsSimpleListType())
			{
				text = JsonConvert.SerializeObject(values);
				value = JsonConvert.DeserializeObject(text, type);
			}
			else
			{
				text = JsonConvert.SerializeObject(text);
				value = JsonConvert.DeserializeObject(text, type);
			}
		}
		else if (@this is JToken)
		{
			var text = JsonConvert.SerializeObject(@this);
			value = JsonConvert.DeserializeObject(text, type);
		}
		else
		{
			var text = JsonConvert.SerializeObject(@this);
			value = JsonConvert.DeserializeObject(text, type);
		}

		return value;
	}
}