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Most people do not understand the knowledge points of this article ".NET Core API formatted output object OutputFormatter", so the editor summarizes the following content, detailed content, clear steps, and has a certain reference value. I hope you can get something after reading this article. Let's take a look at this ".NET Core API formatted output object OutputFormatter how to use" article.

I believe everyone has used the unified response parameter template in the project.

First declare a response template class:

Public class ResponseDto {public int code {get; set;} public string msg {get; set;} public object data {get; set;}}

Then define the methods that return successes and failures:

Public IActionResult Success (object data) {return.} public IActionResult Fail (string msg) {return.}

Call it uniformly when the API returns:

[HttpGet] public IActionResult Get () {var data = new WeatherForecast () {Date = DateTime.Now}; return Success (data);}

Of course, the OutputFormatter mentioned in this article does not conflict with the above unified template, ha. They have something in common. They are both formatted response parameters, which can be used as an introduction.

OutputFormatter

OutputFormatter is the base class for all formatted output, with only one subclass: TextOutputFormatter, while TextOutputFormatter has a large number of subclasses:

JsonOutputFormatter

NewtonsoftJsonOutputFormatter

StringOutputFormatter

SystemTextJsonOutputFormatter

XmlDataContractSerializerOutputFormatter

XmlSerializerOutputFormatter

If no response parameter output format is configured, the default output format of the asp.net core api response parameter is json.

Monkey: this interface returns xml to me. I don't want json.

Me: are you out of your mind? Okay, json, don't use xml.

Well, the front-end boss has to meet the requirements or not, at this time, some students have gone to Baidu: .net how to convert objects into xml?

No No No, it's time for OutputFormatter's grandson XmlDataContractSerializerOutputFormatter to come out.

Simply configure a property for the interface and it's done.

[Produces ("application/xml")] [HttpGet] public WeatherForecast Get () {return new WeatherForecast () {Date = DateTime.Now};}

Let's run it and have a look:

Wtf, how can it be 406?

406: indicates that the client cannot parse the content returned by the server. To put it bluntly, the return result in the background is reported as a 406 error if the foreground cannot be parsed.

Oh, I forgot to configure our grandson XmlDataContractSerializerOutputFormatter in Startup.

Services.AddControllers ((c) = > {c.OutputFormatters.Add (new XmlDataContractSerializerOutputFormatter ());})

Note: not only is there no 406 in Startup, but the following situations also occur:

ContentType does not exist

ContentType does not match response parameters

OutputFormatter extension

The use of built-in OutputFormatter is described above, what if we want to customize it? Of course it's possible.

Let's use a custom OutputFormatter to achieve the effect of the top response template:

Public class ObjectOutputFormatter: TextOutputFormatter {public ObjectOutputFormatter () {SupportedEncodings.Add (Encoding.UTF8); SupportedEncodings.Add (Encoding.Unicode); / / this is the name SupportedMediaTypes.Add ("text/object") of our custom contentType. } public override async Task WriteResponseBodyAsync (OutputFormatterWriteContext context, Encoding selectedEncoding) {if (context = = null) {throw new ArgumentNullException (nameof (context));} if (selectedEncoding = = null) {throw new ArgumentNullException (nameof (selectedEncoding)) } string text = JsonConvert.SerializeObject (new ResponseDto () {msg = "successful, custom", code = 200, data = context.Object}); var response = context.HttpContext.Response Await response.WriteAsync (text, selectedEncoding);}} [Produces ("text/object")] [HttpGet] public WeatherForecast Get () {return new WeatherForecast () {Date = DateTime.Now};} public void ConfigureServices (IServiceCollection services) {services.AddControllers ((c) = > {c.OutputFormatters.Add (new XmlDataContractSerializerOutputFormatter () / / our custom output format c.OutputFormatters.Add (new ObjectOutputFormatter ());});}

All right, let's see how it works:

ActionFilterAttribute

Some students may think of the filter, yes, the above effect filter can also be achieved:

Public class ResultFilter: ActionFilterAttribute {public override void OnResultExecuting (ResultExecutingContext context) {ResponseDto result = new ResponseDto (); result.code = 200; result.msg = "success, ResultFilter"; var properties = context.Result.GetType (). GetProperties (BindingFlags.Instance | BindingFlags.Public); result.data = properties.FirstOrDefault (c = > c.Name = = "Value") .GetValue (context.Result); context.Result = new JsonResult (result) Base.OnResultExecuting (context);}} [TypeFilter (typeof (ResultFilter))] [HttpGet] public WeatherForecast Get () {return new WeatherForecast () {Date = DateTime.Now};}

Monkey: why do you have an OutputFormatter when you have a filter?

Me: you can't think that OutputFormatter is redundant just because the filter can achieve the same function. Obviously, the filter operates on the request / response context, while OutputFormatter operates on the response parameters. Besides, the ActionFilterAttribute filter is just one of many.

Monkey: what will be the effect of using the filter with custom OutputFormatter? Is it like this?

Me: no, the filter and custom OutputFormatter are used at the same time, only the filter is in effect. If you don't believe it, you can try it.

[Produces ("text/object")] [TypeFilter (typeof (ResultFilter))] [HttpGet] public WeatherForecast Get () {return new WeatherForecast () {Date = DateTime.Now};}

The above is about the content of this article on "how to use the .NET Core API formatted output object OutputFormatter". I believe we all have some understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please follow the industry information channel.

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