criteria = {}
    criteria["mm_foot_length"] = mm_foot_length
    criteria["mm_forefoot_width"] = mm_forefoot_width
    if mm_forefoot_height:
        criteria["mm_forefoot_height"] = mm_forefoot_height
    if mm_instep_height:
        criteria["mm_instep_height"] = mm_instep_height
    if mm_heel_width:
        criteria["mm_heel_width"] = mm_heel_width
    query = session.query.filter(**criteria)