matlab.net vs webwrite

Why the function not commented works perfectly, but the function commented always returns error 401 ?

Both use the same <API_KEY>

function [result,tokens] = getGPT4Response(content)
import matlab.net.*
import matlab.net.http.*
% Define the API endpoint
api_endpoint = "https://api.openai.com/v1/chat/completions";

% Define the API key from https://beta.openai.com/account/api-keys
api_key = "<API_KEY>";

data = jsondecode('{"model":"gpt-3.5-turbo","messages":[{"role":"system","content":"You are an assistant."},{"role":"user","content":"'+content+'"}]}');

% Define the headers for the API request
headers(1) = matlab.net.http.HeaderField('Content-Type', 'application/json');
headers(2) = matlab.net.http.HeaderField('Authorization', 'Bearer ' + api_key);

% Define the request message
request = matlab.net.http.RequestMessage('post',headers,data);

% Send the request and store the response
response = send(request, URI(api_endpoint));

% Extract the response text
result = response.Body.Data.choices.message.content;
tokens = response.Body.Data.usage;
end
%**********************************************************************************************************
% function response = getGPT4Response(prompt)
%     % Define the API endpoint
%     url = 'https://api.openai.com/v1/chat/completions'; % Replace with the actual GPT-4 API endpoint when available
% 
%     % Define the headers
%     headers = ["Content-Type:", "application/json"; "Authorization:", "<API_KEY>"];
% 
%     % Define the data
%     message = containers.Map({'role', 'content'}, {'user', prompt});
%     data = containers.Map({'model', 'messages'}, {'gpt-3.5-turbo', {message}});
% 
%     % Convert the data to JSON
%     data = jsonencode(data);
% 
%     % Send the POST request
%     options = weboptions('RequestMethod', 'post', 'HeaderFields', headers, 'MediaType', 'application/json');
%     response = webwrite(url, data, options);
% 
%     % Parse the response
%     response = jsondecode(response);
% 
%     % Extract the text
%     response = response.choices.text;
% end
% 

Answer 1

[Hans Scharler]

There were three issues with the commented function.

1. When you use headers for webwrite you do not have to include the ":" in the header label.
2. The Authorization header needs the word "Bearer" infront of the API Key.
3. webwrite returns an object not JSON.

Here's a working version of the function addressing the issues.

function response = getGPT4Response(prompt)
    % Define the API endpoint
    url = 'https://api.openai.com/v1/chat/completions';
    
    % Define the headers
    headers = ["Content-Type", "application/json"; "Authorization", "Bearer <API_KEY>"];
    
    % Define the data
    message = containers.Map({'role', 'content'}, {'user', prompt});
    data = containers.Map({'model', 'messages'}, {'gpt-3.5-turbo', {message}});
    
    % Convert the data to JSON
    data = jsonencode(data);
    
    % Send the POST request
    options = weboptions('RequestMethod', 'post', 'HeaderFields', headers);
    response = webwrite(url, data, options);
    
    % Return the response
    response = response.choices.message.content;
end

Let me know if you get tihs working.