WebResponse

Web output writer.

This writer is used by the output of the web handler (Web).

In case the value is an exception then it's treated as WebResponse._errorOutput otherwise the value is treated as WebResponse._successOutput.

When an action is executed through a handler it can define options for readers and writers via Metadata support. For instance, you can use it to provide a custom result for a specific handler:

class MyAction extends Mebo.Action{

   // ...

   async _perform(data){
     // ...
   }

   async _after(err, value){
     // defining a custom result that only affects the web handler
     // this call could be done inside of the _perform method. However, we
     // are defining it inside of the _after to keep _perform as
     // abstract as possible. Since, _after is always called (even during
     // an error) after the execution of the action, it provides a way to
     // hook and define custom metadata related with the result.
     if (!err){
         // defining a custom output option
         this.setMeta('$webResult', {
             message: 'My custom web result!',
         });
     }
   }

   // ...
}

Options Summary

Option Name	Description	Default Value
headers	plain object containing the header names (in camel case convention) that should be used in the response	{}
headersOnly	if enabled ends the response without any data
status	success status code (the error status code is driven by the status defined as a member of the exception)	200
root	plain object that gets deep merged at the root of the json output of a success result, for instance: {data: {...}, <rootContentsA>: ..., <rootContentsB> : ...}	{}
result	Overrides the value returned by Writer.value to an arbitrary value (only affects the success output)
resultLabel	custom label used by the success output when the value is serialized using json. This label is used to hold the result under data, for instance: {data: {<resultLabel>: value}} In case of undefined (default) then a fallback label is used based on the value type: - primitive values are held under 'value' - array value is held under 'items' - object is assigned with '' (empty string) * when an empty string is used, the value gets merged to the result.data

When defining options through the metadata support, it can done using option vars. Mebo comes bundled with pre-defined option vars for most of the options available for the readers & writers. The complete list of the option vars can be found at Metadata documentation.

Example of defining the headers option from inside of an action through the metadata support:

// defining 'Content-Type' header
class MyAction extends Mebo.Action{
   async _perform(data){

     // 'Content-Type' header
     this.setMeta('$webHeaders', {
       contentType: 'application/octet-stream',
     });

     // ...
   }
}

Also, headers can be defined through 'before action middlewares' (Web.addBeforeAction and Web.addBeforeAuthAction)