Communication with server via API

Hello all,

I am still a newbie in communication with servers and have the following problem:

I want to automatically translate text from a database using a translator. For this I want to use the LibreTranslator (Link).

LibreTranslate directly provides an example of a query in JavaScript:

const res = await fetch("https://de.libretranslate.com/translate", {
	method: "POST",
	body: JSON.stringify({
		q: "",
		source: "auto",
		target: "de",
		format: "text",
		api_key: ""
	}),
	headers: { "Content-Type": "application/json" }
});

console.log(await res.json());

Now I would like to implement this request in MATLAB. For this I have resorted to webwrite and tried to write a query as in this Example.

The content of my function is as follows:

api = 'https://de.libretranslate.com/translate';

body.q= "";
body.source = "auto";
body.target = "de";
body.format = 'text';
body.api_key = '';

if ~exist('options','var')
    options = weboptions;
end
options.RequestMethod="post";
options.MediaType = "application/json";
s = webwrite(api,body,options);

When I run this now I get the following error:

---------------------------------------------------------------------------------------------------------------------------------------------------

Error using matlab.internal.webservices.HTTPConnector/copyContentToByteArray

The server returned the status 500 with message "Internal Server Error" in response to the request to URL

https://de.libretranslate.com/translate.

---------------------------------------------------------------------------------------------------------------------------------------------------

I have also already tried to create a json file that has exactly the structure from the example query and pass this. The result remained the same.

{
	"methods": "POST",
	"body": {
		"q": "Hello",
		"source": "auto",
		"target": "de",
		"format": "text",
		"api_key": ""
	},
	"headers": {
		"Content-Type": "application/json"
	}
}

I would be very happy if someone could help me here.

Many thanks and many greetings

Tom

Answer 1

[Chetan]

Hello @Tom Bernand,

It appears you're encountering a "500 Internal Server Error" while trying to send a POST request to the LibreTranslate API for text translation from MATLAB, following a JavaScript example.

To tackle this in MATLAB, consider the following steps:

• JSON Formatting: Make sure your data structure aligns with what the API expects. MATLAB's `webwrite` function automatically converts structures to JSON
• Headers and Options: You correctly set the `MediaType` to `"application/json"`. Ensure you check and include any other necessary headers or options.
• API Key: If the API demands an API key, verify its validity and include it in your request.

Here's a revised code snippet:

api = 'https://de.libretranslate.com/translate';
body = struct('q', "Hello", 'source', "auto", 'target', "de", 'format', 'text', 'api_key', '');
options = weboptions('RequestMethod', 'post', 'MediaType', 'application/json', 'Timeout', 30);
try
    response = webwrite(api, body, options);
    disp(response);
catch ME
    disp('Error occurred:');
    disp(ME.message);
end

    detectedLanguage: [1x1 struct]
      translatedText: 'hallo'

Refer to the following MathWorks Documentation for more details:

• https://www.mathworks.com/help/matlab/ref/webwrite.html
• https://www.mathworks.com/help/matlab/ref/weboptions.html

Hope this helps!

[Tom Bernand]

Hello Chetan,

Thank you very much for your help!