C#•10mo ago

❔ [EFCore] What is the right approach to generate hierarchy id for new child entity?

I Use SQLServer & EF Core. been struggling to find the right approach to generate new h-id for new child entities for a while now. and most approaches online are just straight up inserting duplicates or doing multiple queries with really possible scare-y edge cases that can cause alot of trouble.

3 Replies

CaptainSh4dow•10mo ago

like this article shows a method where there guy inserts another /1/ which is a violation iirc. you can't have duplicate h-id paths https://www.meziantou.net/using-hierarchyid-with-entity-framework-core.htm

Meziantou's blog

Using SQL Server HierarchyId with Entity Framework Core - Gérald Ba...

In this post, I describe how to use the HierarchyId data type with Entity Framework Core.

CaptainSh4dow•10mo ago

my current approach that does two queries

public static HierarchyId GeneratePathForChild(HierarchyId? parent, HierarchyId? lastChildId)
{

    //Handling Fatherless Entities.
    if (parent is null)
        return HierarchyId.Parse("/");

    //Handling Entities With No Sister Entities.
    if (lastChildId is null)
        return HierarchyId.Parse($"{parent}{1}/");

    //Handling Entities With Sister Entities
    var lastDigit = lastChildId.ToString().Split("/", StringSplitOptions.RemoveEmptyEntries).Last();
    var lastDigitNumber = int.Parse(lastDigit);
    return HierarchyId.Parse($"{parent}{lastDigitNumber + 1}/");

}

public static HierarchyId GeneratePathForChild(HierarchyId? parent, HierarchyId? lastChildId)
{

    //Handling Fatherless Entities.
    if (parent is null)
        return HierarchyId.Parse("/");

    //Handling Entities With No Sister Entities.
    if (lastChildId is null)
        return HierarchyId.Parse($"{parent}{1}/");

    //Handling Entities With Sister Entities
    var lastDigit = lastChildId.ToString().Split("/", StringSplitOptions.RemoveEmptyEntries).Last();
    var lastDigitNumber = int.Parse(lastDigit);
    return HierarchyId.Parse($"{parent}{lastDigitNumber + 1}/");

}

one query to load the parent. and the other to load the last child.

Accord•10mo ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity. Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ [EFCore] What is the right approach to generate hierarchy id for new child entity?