Question

我正在开发基于ASP.NET Core Web API的REST服务，并希望在我的端点添加一个参数'prettify'，以便响应json将使用缩进格式化并在Web浏览器中可读。

我的问题 - 如何在ASP.WEB API Core应用程序中为每个控制器方法更改JSON格式？

感谢您的帮助。

Answer 1

感谢@Nkosi评论，我找到了解决方案。下面是一个动作过滤器的代码，它查找'prettify'参数并为输出JSON添加缩进。如果省略参数，则还会添加缩进。

public class OutputFormatActionFilter : IActionFilter
{
    public void OnActionExecuting(ActionExecutingContext context)
    {
    }

    public void OnActionExecuted(ActionExecutedContext context)
    {
        var actionResult = context.Result as ObjectResult;
        if (actionResult == null) return;

        var paramObj = context.HttpContext.Request.Query["prettify"];
        var isPrettify = string.IsNullOrEmpty(paramObj) || bool.Parse(paramObj);

        if (!isPrettify) return;

        var settings = new JsonSerializerSettings { Formatting = Formatting.Indented };

        actionResult.Formatters.Add(new JsonOutputFormatter(settings, ArrayPool<char>.Shared));
    }
}

Answer 2

创建一个操作过滤器，可用于要添加该功能的操作。我使用DelegatingHandler在Asp.Net Web API 2（非核心）中实现了相同的功能，它将检查请求并根据URL中的prettify=true查询参数更新json格式化程序的缩进

以下是如何使用委托处理程序

完成的

/// <summary>
/// Custom handler to allow pretty print json results.
/// </summary>
public class PrettyPrintJsonHandler : DelegatingHandler {
    const string prettyPrintConstant = "pretty";
    MediaTypeHeaderValue contentType = MediaTypeHeaderValue.Parse("application/json;charset=utf-8");
    private System.Web.Http.HttpConfiguration httpConfig;
    /// <summary>
    /// Initializes a new instance of the <seealso cref="PrettyPrintJsonHandler"/> class with an HTTP Configuration.
    /// </summary>
    /// <param name="config"></param>
    public PrettyPrintJsonHandler(System.Web.Http.HttpConfiguration config) {
        this.httpConfig = config;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) {
        var canPrettyPrint = checkQuery(request.RequestUri.Query);
        var jsonFormatter = httpConfig.Formatters.JsonFormatter;
        jsonFormatter.Indent = canPrettyPrint;

        var response = await base.SendAsync(request, cancellationToken);

        if (canPrettyPrint && response.Content != null) {
            response.Content.Headers.ContentType = contentType;
        }

        return response;
    }

    private bool checkQuery(string queryString) {
        var canPrettyPrint = false;
        if (!string.IsNullOrWhiteSpace(queryString)) {
            var prettyPrint = QueryString.Parse(queryString)[prettyPrintConstant];
            canPrettyPrint = !string.IsNullOrWhiteSpace(prettyPrint) && Boolean.TryParse(prettyPrint, out canPrettyPrint) && canPrettyPrint;
        }
        return canPrettyPrint;
    }
}

在安装过程中添加为全局消息处理程序。

相同的概念可以应用于动作过滤器。

Asp WebApi：Prettify ActionResult JSON输出

2 个答案: