I am trying to use SetValue on IContent to programmatically set the value of a dropdown list. I can set the value of Textboxes no issue but not Dropdownlists.

I have seen solutions for version 7 but I can't find anything for version 8

private void SetDropDownListValue(IContent content, int dropDownListDataTypeId, string propertyName, string prevalue)
{
  var dropdown = _DataTypeService.GetAll().First(x => x.Id == dropDownListDataTypeId);

  IDataType dataType = _DataTypeService.GetDataType(dropdown.Id);

  //valueList looks good, can see all prevalues
  ValueListConfiguration valueList = (ValueListConfiguration)dataType.Configuration;

  ValueListItem item = valueList.Items.SingleOrDefault(i => i.Value == prevalue);

  if (item != null)
  {
    //item.Id looks good, a simple integer but content crash in backoffice
    //item.Value looks correct too
    content.SetValue(propertyName, item.Id);
  }
}

I get this in the backoffice when viewing this content

Version 7 solution: https://our.umbraco.com/forum/developers/api-questions/54462-Set-value-of-UmbracoDropDown-programatically