def METHOD_NAME(model, form, file_category, field_name):
    """
    Merge change for a single file form field
    :param model: Model instance
    :param form: form wrapper
    :param file_category: File type
    :param field_name: field name in model and form
    :return: True if there were changes
    """
    from civictechprojects.models import ProjectFile
    field_changed = False
    file_content = read_form_field(form, field_name)
    if file_content and len(file_content) > 0:
        file_json = json.loads(file_content)
        if isinstance(file_json, list):
            file_json = file_json[0] if len(file_json) > 0 else []
        field_changed = ProjectFile.replace_single_file(model, file_category, file_json)
    return field_changed