在drupal 7中以编程方式插入节点字段值。

I'm trying to insert values for a node field from a custom module. The value will only be inserted from that module and then no operation for that node will be performed, so hook is not in my consideration. I've tried to directly insert values to the field_data_... and field_revision_... tables. but I've found that drupal also saves the values (serialized) in field_config and field_config_instance tables as blob. since I'm only inserting values in two tables drupal is not reading values I've inserted for nodes. I couldn't understand the serialization stored in DB. so I'm searching for a method that will help me to insert values through API or any other neat way.I'm trying to insert values for a node field fr