❔ How to get all children of parent node?

E

ero•3/9/23, 11:16 AM

what children?

E

ero•3/9/23, 11:16 AM

i don't see any there

T

Thinker•3/9/23, 11:21 AM

I think you'll need something like

dbContext.Nodes.Where(node => node.ParentId == id)

dbContext.Nodes.Where(node => node.ParentId == id)

dbContext.Nodes.Where(node => node.ParentId == id)

dbContext.Nodes.Where(node => node.ParentId == id)

T

Thinker•3/9/23, 11:22 AM

and then also do that for all of those children

T

Thinker•3/9/23, 11:26 AM

something like this

IEnumerable<Node> GetDescendants(Node node)
{
    var children = dbContext.Nodes.Where(n => n.ParentId == node.Id);
    return children.Concat(children.SelectMany(GetDescendants));
}

IEnumerable<Node> GetDescendants(Node node)
{
    var children = dbContext.Nodes.Where(n => n.ParentId == node.Id);
    return children.Concat(children.SelectMany(GetDescendants));
}

IEnumerable<Node> GetDescendants(Node node)
{
    var children = dbContext.Nodes.Where(n => n.ParentId == node.Id);
    return children.Concat(children.SelectMany(GetDescendants));
}

IEnumerable<Node> GetDescendants(Node node)
{
    var children = dbContext.Nodes.Where(n => n.ParentId == node.Id);
    return children.Concat(children.SelectMany(GetDescendants));
}

T

Thinker•3/9/23, 11:27 AM

of course assuming you're using Entity Framework (or this isn't a database at all)

Eero i don't see any there

.

.perceptronOP•3/9/23, 11:36 AM

{
    "data": [
        {
            "id": 2,
            "name": "General",
            "parentId": "0"
        },
        {
            "id": 3,
            "name": "Fruits",
            "parentId": "2"
        },
        {
            "id": 6,
            "name": "Vegetables",
            "parentId": "2"
        },
        {
            "id": 12,
            "name": "Apple",
            "parentId": "3"
        }
    ],
    "success": true,
    "messages": null
}

{
    "data": [
        {
            "id": 2,
            "name": "General",
            "parentId": "0"
        },
        {
            "id": 3,
            "name": "Fruits",
            "parentId": "2"
        },
        {
            "id": 6,
            "name": "Vegetables",
            "parentId": "2"
        },
        {
            "id": 12,
            "name": "Apple",
            "parentId": "3"
        }
    ],
    "success": true,
    "messages": null
}

{
    "data": [
        {
            "id": 2,
            "name": "General",
            "parentId": "0"
        },
        {
            "id": 3,
            "name": "Fruits",
            "parentId": "2"
        },
        {
            "id": 6,
            "name": "Vegetables",
            "parentId": "2"
        },
        {
            "id": 12,
            "name": "Apple",
            "parentId": "3"
        }
    ],
    "success": true,
    "messages": null
}

{
    "data": [
        {
            "id": 2,
            "name": "General",
            "parentId": "0"
        },
        {
            "id": 3,
            "name": "Fruits",
            "parentId": "2"
        },
        {
            "id": 6,
            "name": "Vegetables",
            "parentId": "2"
        },
        {
            "id": 12,
            "name": "Apple",
            "parentId": "3"
        }
    ],
    "success": true,
    "messages": null
}

E

ero•3/9/23, 11:37 AM

i see

E

ero•3/9/23, 11:37 AM

yeah you wanna do what thinkger suggested

..perceptron I have a DTO as image. I want to get all children (included children of child) ....

S

SWEETPONY•3/9/23, 11:48 AM

internal static class GenericHelpers
{
    public static IEnumerable<TreeItem<T>> GenerateTree<T, K>(
        this IEnumerable<T> collection,
        Func<T, K> idSelector,
        Func<T, K> parentIdSelector,
        K rootId = default( K ) )
    {
        foreach ( var c in collection.Where( c => EqualityComparer<K>.Default.Equals( parentIdSelector( c ), rootId ) ) )
        {
            yield return new TreeItem<T>
            {
                Item = c,
                Children = collection.GenerateTree( idSelector, parentIdSelector, idSelector( c ) )
            };
        }
    }
}

var root = yourCollection.GenerateTree(
            item=> item.Id, 
            item=> item.ParentId );

internal static class GenericHelpers
{
    public static IEnumerable<TreeItem<T>> GenerateTree<T, K>(
        this IEnumerable<T> collection,
        Func<T, K> idSelector,
        Func<T, K> parentIdSelector,
        K rootId = default( K ) )
    {
        foreach ( var c in collection.Where( c => EqualityComparer<K>.Default.Equals( parentIdSelector( c ), rootId ) ) )
        {
            yield return new TreeItem<T>
            {
                Item = c,
                Children = collection.GenerateTree( idSelector, parentIdSelector, idSelector( c ) )
            };
        }
    }
}

var root = yourCollection.GenerateTree(
            item=> item.Id, 
            item=> item.ParentId );

internal static class GenericHelpers
{
    public static IEnumerable<TreeItem<T>> GenerateTree<T, K>(
        this IEnumerable<T> collection,
        Func<T, K> idSelector,
        Func<T, K> parentIdSelector,
        K rootId = default( K ) )
    {
        foreach ( var c in collection.Where( c => EqualityComparer<K>.Default.Equals( parentIdSelector( c ), rootId ) ) )
        {
            yield return new TreeItem<T>
            {
                Item = c,
                Children = collection.GenerateTree( idSelector, parentIdSelector, idSelector( c ) )
            };
        }
    }
}

var root = yourCollection.GenerateTree(
            item=> item.Id, 
            item=> item.ParentId );

internal static class GenericHelpers
{
    public static IEnumerable<TreeItem<T>> GenerateTree<T, K>(
        this IEnumerable<T> collection,
        Func<T, K> idSelector,
        Func<T, K> parentIdSelector,
        K rootId = default( K ) )
    {
        foreach ( var c in collection.Where( c => EqualityComparer<K>.Default.Equals( parentIdSelector( c ), rootId ) ) )
        {
            yield return new TreeItem<T>
            {
                Item = c,
                Children = collection.GenerateTree( idSelector, parentIdSelector, idSelector( c ) )
            };
        }
    }
}

var root = yourCollection.GenerateTree(
            item=> item.Id, 
            item=> item.ParentId );

A

Accord•3/10/23, 12:18 PM

Was this issue resolved? If so, run

/close

/close

otherwise I will mark this as stale and this post will be archived until there is new activity.