Automatic conversion

This page is part of the magic.lambda.http documentation.

You can also automatically convert the resulting response object to a lambda object if you have a registered conversion function, and you provide a [convert] argument, and set its value to boolean true. Below is an example.

http.get:"https://jsonplaceholder.typicode.com/posts"
   convert:bool:true

The above will result in something resembling the following.

http.get:int:200
   headers
      Date:"Mon, 29 Nov 2021 06:19:29 GMT"
      Transfer-Encoding:chunked
      Connection:keep-alive
      // ... etc ...
   content
      .
         userId:long:1
         id:long:1
         title:sunt aut facere repellat provident occaecati excepturi optio reprehenderit
         body:qwerty1
      .
         userId:long:1
         id:long:2
         title:qui est esse
         body:qwerty2
      // ... etc ...

The project contains automatic conversions for the following types out of the box, but you can easily register your own C# based conversion types for specific “Content-Type” values.

• application/json
• application/x-json
• application/hyperlambda
• application/x-hyperlambda
• application/www-form-urlencoded
• application/x-www-form-urlencoded
• multipart/form-data

You can also convert a semantic lambda object to the correct request content in a similar fashion, by instead of providing a value to your [payload] node provide a lambda object such as illustrated below.

.userId:int:1
http.post:"https://jsonplaceholder.typicode.com/posts"
   payload
      id:int:1
      userId:x:@.userId

The above will transform your payload to a JSON object automatically for you, and also unwrap any expressions found in your lambda object before JSON transformation is applied. Automatic transformation will only be applied if you’ve got a transformation function registered. If you want to extend the list of supported content types to automatically transform back and forth to, you can use either Magic.Http.AddRequestHandler or MagicHttp.AddResponseHandler to add support for your own automatic transformation for both the request payload and/or the response content.

Notice - The [payload] node above must have a null value, otherwise the slot will prioritise the value, and not attempt to transform from a semantic lambda object in any ways. Values in your [payload] will be transferred as is, and you can provide byte[] arrays, streams or strings as the value of your [payload] node.

Notice - Both the URL encoded request transformer and the JSON request transformer will automatically evaluate expressions in your semantic [payload] object, but this is not true for the Hyperlambda request transformer, since in Hyperlambda it might make sense to actually pass in expressions to the endpoint. Below is an example of how to semantically pass in a Hyperlambda object to some URL.

http.post:"https://foo.com/hyperlambda-endpoint"
   headers
      Content-Type:application/hyperlambda
   payload
      .foo
         .:Thomas
         .:John
      for-each:x:@.foo
         // ... etc ...

The above will automatically serialize your lambda object as Hyperlambda, since the Content-Type is of a type supported by the automatic conversion functions, and transfer the request as a string to the endpoint, preserving expressions as is without unwrapping them before transmitting your [payload].

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