---
title: Categories (dev)
slug: commerce-connect-15/docs/categories-dev
docTags: 
createdAt: 2026-07-30T20:34:41.000Z
---

Categories are represented by the `EPiServer.Commerce.Catalog.Linking.NodeRelation` class and administered using the `EPiServer.Commerce.Catalog.Linking.IRelationRepository` service.

The `Parent` property of the `NodeRelation` contains the `ContentReference` of the category. You can categorize each entry and category. The class also has a `SortOrder` property that describes the order of the categories.

A `NodeRelation` is uniquely defined by the `ContentReference` in its `Parent` and `Child` property (referencing the categorized item). You cannot add the same category more than once to an entry or another category.

For categorizations of entries, you can work with the `NodeEntryRelation` type instead of the `NodeRelation` type. `NodeEntryRelation` derives from `NodeRelation` and exposes the additional `IsPrimary` property, describing whether the relation is the primary category for the entry.

While each entry can have multiple categories linking it to several categories, only one can be the primary relation. The primary relation specifies the entry's primary or *home* category. This category is used when building the entry's default hierarchical URL.

## Get the categories of an entry or category

To get categories, call the `GetChildren` method of `IRelationRepository` with the `ContentReference` of an entry or category.

```csharp
public IEnumerable<NodeRelation> ListCategories(ContentReference referenceToEntryOrCategory)
{
  var relationRepository = ServiceLocator.Current.GetInstance<IRelationRepository>();
  var categories = relationRepository.GetChildren<NodeRelation>(referenceToEntryOrCategory);
  return categories;
}
```

### Add a category to an entry or another category

To add `NodeRelation` objects to an entry or category, use the `UpdateRelations` method or `UpdateRelation` extension method of `IRelationRepository`. The new category must have a `Parent ContentReference` and a `Child ContentReference`.

```csharp
public void AddCategory(ContentReference referenceToEntryOrCategory, ContentReference referenceToCategory)
{
  var relationRepository = ServiceLocator.Current.GetInstance<IRelationRepository>();
  var newCategory = new NodeRelation
    {
      SortOrder = 100,
      Child = referenceToEntryOrCategory,
      Parent = referenceToCategory
    };
  relationRepository.UpdateRelation(newCategory);
}
```

### Remove a category from an entry or another category

To remove a category, call the `RemoveRelations` method or `RemoveRelation` extension method of `IRelationRepository` with a `NodeRelation` object matching an existing category. You can construct a matching object, or use `GetChildren` or `GetParents` to get the existing `Relations`, filter out the object you want to remove, and pass it to `RemoveRelation`.

```csharp
public void RemoveCategory(ContentReference referenceToEntryOrCategory, ContentReference referenceToCategory)
{
  var relationRepository = ServiceLocator.Current.GetInstance<IRelationRepository>();
  // Define a relation matching the one to remove, or use
  // GetRelations to find the one you want to remove and pass that to
  // RemoveRelation
  var relationToRemove = new NodeRelation
    {
      Child = referenceToEntryOrCategory,
      Parent = referenceToCategory
    };
  // Removes matching NodeRelation, or no action if no match exists
  relationRepository.RemoveRelation(relationToRemove);
}
```