title: How to filter Many2one value depend another field?
body: <p>please I have a custom module here is a capture :</p>
  
  <p><a href="https://i.stack.imgur.com/ATK5z.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ATK5z.png" alt="enter image description here"></a></p>
  
  <p>then I go to Sales order and modify the module sale.order.line i add some fields in relation with my custom module</p>
  
  <p><a href="https://i.stack.imgur.com/QSVkL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QSVkL.png" alt="enter image description here"></a></p>
  
  <p>Now my request is in ligne contrat i want only lignes in the contrat </p>
  
  <p>for example if i choose <strong>Contrat 01</strong> only ligne in <strong>Contrat 01</strong>  like this</p>
  
  <p><a href="https://i.stack.imgur.com/tAZFa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tAZFa.png" alt="enter image description here"></a></p>
  
  <p>here is my code : </p>
  
  <p><a href="https://i.stack.imgur.com/f0jWg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/f0jWg.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/rFVeO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rFVeO.png" alt="enter image description here"></a></p>