fix: add a POST version of /predict/lang endpoint

doc/references/api.yml

@@ -1027,6 +1027,13 @@ paths:
       tags:
         - Predict
       summary: Predict the language of a text
+      description: |
+        Predict the language of a text using a neural model.
+        A POST version of this endpoint is also available, it accepts a JSON body with exactly the
+        same parameters.
+
+        Use the POST version if you want to predict the language of a long text, as the GET version
+        has a limit on the length of the text that can be provided.
       parameters:
         - name: text
           in: query

robotoff/app/api.py

@@ -651,8 +651,11 @@ def on_get(self, req: falcon.Request, resp: falcon.Response):
 
 
 class LanguagePredictorResource:
-    def on_get(self, req: falcon.Request, resp: falcon.Response):
-        """Predict language of a text."""
+    def _on_get_post(self, req: falcon.Request, resp: falcon.Response):
+        """Predict language of a text.
+
+        This method is used by both GET and POST endpoints.
+        """
         params = validate_params(
             {
                 "text": req.get_param("text"),
@@ -669,6 +672,18 @@ def on_get(self, req: falcon.Request, resp: falcon.Response):
             ]
         }
 
+    def on_get(self, req: falcon.Request, resp: falcon.Response):
+        """Predict language of a text."""
+        self._on_get_post(req, resp)
+
+    def on_post(self, req: falcon.Request, resp: falcon.Response):
+        """Predict language of a text.
+
+        For long text, use POST instead of GET, as the length of the query
+        string is limited.
+        """
+        self._on_get_post(req, resp)
+
 
 class UpdateDatasetResource:
     def on_post(self, req: falcon.Request, resp: falcon.Response):