public async Task <IActionResult> PostAttribute([FromBody] Attribute attribute)
        {
            if (!ModelState.IsValid)
            {
                return(HttpResponseHelper.BadRequest(ModelState));
            }

            _context.Attributes.Add(attribute);

            var error = await SaveChangesAsync();

            if (error != null)
            {
                return(error);
            }

            return(CreatedAtRoute("GetAttribute", new { id = attribute.Id }, attribute));
        }
        public async Task <IActionResult> PutAttribute([FromRoute] Guid id, [FromBody] Attribute attribute)
        {
            if (!ModelState.IsValid)
            {
                return(HttpResponseHelper.BadRequest(ModelState));
            }

            if (id != attribute.Id)
            {
                return(HttpResponseHelper.BadRequest("Invalid Attribute Id."));
            }

            _context.Entry(attribute).State = EntityState.Modified;

            var error = await SaveChangesAsync();

            if (error != null)
            {
                return(error);
            }

            return(CreatedAtRoute("GetAttribute", new { id = attribute.Id }, attribute));
        }