How can I find gameobject with tag that are childs of a specific parent?

Question

public void UpdateOrAddShaderPrefabToDoors()
    {
        GameObject[] doorsLeft = GameObject.FindGameObjectsWithTag(c_doorLeft);
        GameObject[] doorsRight = GameObject.FindGameObjectsWithTag(c_doorRight);

        List<GameObject> allDoors = doorsLeft.Union(doorsRight).ToList();

        HashSet<GameObject> prefabParentsOfDoorsNeedRemove = new HashSet<GameObject>();
        allDoors.ForEach(doorGameObject =>
        {
            List<GameObject> shadersChildren = new List<GameObject>();
            for (int i=0; i<doorGameObject.transform.childCount ;i++)
            {
                if (doorGameObject.transform.GetChild(i).name.StartsWith(c_doorShieldFxLocked))
                {
                    shadersChildren.Add(doorGameObject.transform.GetChild(i).gameObject);
                }
            }
            foreach (GameObject shader in shadersChildren)
            {
                GameObject outermostPrefabInstanceRoot = PrefabUtility.GetOutermostPrefabInstanceRoot(shader);
                prefabParentsOfDoorsNeedRemove.Add(outermostPrefabInstanceRoot);
            }
        });

        foreach (GameObject parent in prefabParentsOfDoorsNeedRemove)
        {
            Modify(parent, RemoveFunc);
        }

        HashSet<GameObject> prefabParentsOfDoors = new HashSet<GameObject>();
        allDoors.ForEach(doorGameObject =>
        {
            GameObject outermostPrefabInstanceRoot = PrefabUtility.GetOutermostPrefabInstanceRoot(doorGameObject);
            prefabParentsOfDoors.Add(outermostPrefabInstanceRoot);
        });

        foreach (GameObject parent in prefabParentsOfDoors)
        {
            AddShaderToPrefab(parent);
        }
    }

When doing :

GameObject[] doorsLeft = GameObject.FindGameObjectsWithTag(c_doorLeft);
GameObject[] doorsRight = GameObject.FindGameObjectsWithTag(c_doorRight);

It will find all "Door_Left" and "Door_Right" but some of them are childs of other gameobjects and I want to find the door left and door right only that are childs of : Wall_Door_Long_01

Answer 1

Have you tried something like

GameObject[] doorsLeft = GameObject.FindGameObjectsWithTag(c_doorLeft).Where(o => o.transform.parent.name == "Wall_Door_Long_01");

You might want to use string compare rather than == but, as an example.

Answer 2

You could check all child of that object.

List<GameObject> doorsLeft = new List<GameObject>();
foreach (Transform child in transform){
    if (child.tag == tag){
        doorsLeft.add(child.gameObject);
    }
}