Can the httpclient handle json primitives in the response? - Progress Community

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Can the httpclient handle json primitives in the response?

If the response to an http request is a primitive valaue, through the httpclient, how does the httpclient handle it. Can the httpclient handle an http response that is a json primitive value?

Jul 15, 2020
Knowledge

Title

Can the httpclient handle json primitives in the response?

URL Name

Can-the-httpclient-handle-json-primitives-in-the-response

Article Number

000193971

Environment

Product: OpenEdge Version: 11.7.x, 12.x OS: All supported platforms Other: httpclient

Question/Problem Description

Can the httpclient handle a response that is a json primitive value?
Can a json primitive value be handled by the httpclient in a response to a request?
How to handle a json primitive value in a response to a request made by the httpclient.

Steps to Reproduce

Clarifying Information

Error Message

Defect Number

Enhancement Number

Cause

Resolution

The ABL does not have support for JSON that is not an JsonObject or JsonArray. The httpclient uses these types for its JSON response data, as well as the JsonObjectModel parser. Thus the httpclient does not deal with JSON primitive values.

Workaround

In this case the customer was expecting true or false to be returned.
This can be handled as follows:
Cast the response's entity to a memptr. Use the GetString method to extract the response value and then use the response value as needed by the application.

The following is a code snippet demonstrating how this might be accomplished:

USING OpenEdge.Net.HTTP.IHttpRequest.
USING OpenEdge.Net.HTTP.IHttpResponse.
USING OpenEdge.Net.HTTP.ClientBuilder.
USING OpenEdge.Net.HTTP.RequestBuilder.
USING Progress.Lang.Object. 

DEFINE VARIABLE oRequest  AS IHttpRequest NO-UNDO.
DEFINE VARIABLE oResponse AS IHttpResponse NO-UNDO.
DEFINE VARIABLE oEntity AS Object NO-UNDO.
define variable cData as longchar no-undo.

oRequest = RequestBuilder:GET("<URL to use>")
:AddHeader("Content-Type", "text/plain")
:Request.
oResponse = oClient:Execute(oRequest).
oEntity = oResponse:Entity. 
cData = cast(oEntity, OpenEdge.Core.Memptr):GetString(1).
case cData:
when 'true' or when 'false' then ...
when null then ..
// deal with numbers
// deal with dates
// deal with strings
end case.

Notes

References to other Documentation:

Programming Interfaces: Input/Output Processes : Making HTTP(S) requests from ABL applications:
https://documentation.progress.com/output/ua/OpenEdge_latest/index.html#page/dvpin%2Fmaking-http(s)-requests-from-abl-applications.html%23

Progress article(s):
How to perform a simple GET request using the HttpClient?

Keyword Phrase

Last Modified Date

11/20/2020 6:52 AM

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Can the httpclient handle json primitives in the response? - Progress Community