Se modifico un poco el layout y la opcion de cambiar la categoria

files/files.py

@@ -99,8 +99,9 @@ def upload_file():
 @bp.route('/preview/<int:id>')
 def preview_file(id):
     file = File.query.get(id)
+    categories = Category.query.all()
     if (file.private == 1 and g.user is not None) or (file.private == 0):
-        return render_template('files/preview.html', file=file)
+        return render_template('files/preview.html', file=file, categories=categories)
     else:
         return abort(404)
 
@@ -108,28 +109,45 @@ def preview_file(id):
 @bp.route('/rename/<int:id>', methods=['POST'])
 @admin_required
 def rename_file(id):
-    if request.method == 'POST':
-        file = File.query.get(id)
+    file = File.query.get(id)
 
-        new_name = request.form['new_name'].lower()
-        extension = file.filename.rsplit('.', 1)[1].lower()
+    new_name = request.form['new_name'].lower()
+    extension = file.filename.rsplit('.', 1)[1].lower()
 
-        if "." in new_name and _get_extension(new_name):
-            new_name = new_name.rsplit('.', 1)[0] + '.' + extension
-        else:
-            new_name = new_name + '.' + extension
+    if "." in new_name and _get_extension(new_name):
+        new_name = new_name.rsplit('.', 1)[0] + '.' + extension
+    else:
+        new_name = new_name + '.' + extension
 
-        _rename_file(file, new_name)
+    _rename_file(file, new_name)
 
-        return redirect(url_for('files.preview_file', id=file.id))
+    return redirect(url_for('files.preview_file', id=file.id))
+
+
+@bp.route('/recategorize/<int:id>', methods=['POST'])
+@admin_required
+def recategorize(id):
+    file = File.query.get(id)
+     
+    if 'new_category' not in request.form:
+        flash('No category selected')
+        return redirect(request.url)
+
+    new_category = Category.query.get(request.form['new_category'])
+    if new_category is None:
+        flash('The category selected won\'t exists')
+        return redirect(request.url)
+    
+    file.category_id = new_category.id
+    db.session.commit()
+
+    return redirect(url_for('files.preview_file', id=file.id))
+    
 
 
 @bp.route('/delete/<int:id>', methods=['POST'])
 @admin_required
 def delete_file(id):
-    if request.method == 'POST':
-        file = File.query.get(id)
-        _delete_file(file)
-        return redirect(url_for('index'))
-    else:
-        abort(404)
+    file = File.query.get(id)
+    _delete_file(file)
+    return redirect(url_for('index'))