Fix POST/PUT being converted to GET during HTTP→HTTPS redirect

src/main/java/cz/zcu/kiv/eegdatabase/web/filters/HttpToHttpsPreserveMethodFilter.java

@@ -0,0 +1,33 @@
+package cz.zcu.kiv.eegdatabase.web.filters;
+
+import javax.servlet.*;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+public class HttpToHttpsPreserveMethodFilter implements Filter {
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+            throws IOException, ServletException {
+
+        HttpServletRequest req = (HttpServletRequest) request;
+        HttpServletResponse res = (HttpServletResponse) response;
+
+        if (req.getScheme().equals("http")) {
+            String method = req.getMethod();
+            String url = "https://" + req.getServerName() + req.getRequestURI();
+
+            String qs = req.getQueryString();
+            if (qs != null) {
+                url += "?" + qs;
+            }
+
+            res.setStatus(308); // preserve POST/PUT on redirect
+            res.setHeader("Location", url);
+            return;
+        }
+
+        chain.doFilter(request, response);
+    }
+}

src/main/webapp/WEB-INF/web.xml

@@ -126,6 +126,19 @@
         <filter-name>cross-origin</filter-name>
         <url-pattern>/*</url-pattern>
     </filter-mapping>
+
+    <!-- Fix: Preserve PUT/POST during HTTP → HTTPS redirect -->
+    <filter>
+        <filter-name>httpToHttpsPreserveMethodFilter</filter-name>
+        <filter-class>cz.zcu.kiv.eegdatabase.web.filters.HttpToHttpsPreserveMethodFilter</filter-class>
+    </filter>
+
+    <filter-mapping>
+        <filter-name>httpToHttpsPreserveMethodFilter</filter-name>
+        <url-pattern>/*</url-pattern>
+    </filter-mapping>
+
+
     <!-- Filter mappings starting -->
     <filter-mapping>
         <filter-name>springSecurityFilterChain</filter-name>