Trees

Full Tree in Single Document

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<?php

#[Document]
class BlogPost
{
    #[Id]
    private string $id;

    #[Field(type: 'string')]
    private string $title;

    #[Field(type: 'string')]
    private string $body;

    /** @var Collection<Comment> */
    #[EmbedMany(targetDocument: Comment::class)]
    private Collection $comments;

    // ...
}

#[EmbeddedDocument]
class Comment
{
    #[Field(type: 'string')]
    private string $by;

    #[Field(type: 'string')]
    private string $text;

    /** @var Collection<Comment> */
    #[EmbedMany(targetDocument: Comment::class)]
    private Collection $replies;

    // ...
}
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Retrieve a blog post and only select the first 10 comments:

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<?php

$post = $dm->createQueryBuilder(BlogPost::class)
    ->selectSlice('replies', 0, 10)
    ->getQuery()
    ->getSingleResult();

$replies = $post->getReplies();
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You can read more about this pattern on the MongoDB documentation page Trees in MongoDB in the Full Tree in Single Document section.

Parent Reference

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<?php

#[Document]
class Category
{
    #[Id]
    private string $id;

    #[Field(type: 'string')]
    private string $name;

    #[ReferenceOne(targetDocument: Category::class)]
    #[Index]
    private ?Category $parent = null;

    // ...
}
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Query for children by a specific parent id:

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<?php

$children = $dm->createQueryBuilder(Category::class)
    ->field('parent.id')->equals('theid')
    ->getQuery()
    ->execute();
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You can read more about this pattern on the MongoDB documentation page Trees in MongoDB in the Parent Links section.

Child Reference

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<?php

#[Document]
class Category
{
    #[Id]
    private string $id;

    #[Field(type: 'string')]
    private string $name;

    /** @var Collection<Category> */
    #[ReferenceMany(targetDocument: Category::class)]
    #[Index]
    private Collection $children;

    // ...
}
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Query for immediate children of a category:

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<?php

$category = $dm->createQueryBuilder(Category::class)
    ->field('id')->equals('theid')
    ->getQuery()
    ->getSingleResult();

$children = $category->getChildren();
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Query for immediate parent of a category:

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<?php

$parent = $dm->createQueryBuilder(Category::class)
    ->field('children.id')->equals('theid')
    ->getQuery()
    ->getSingleResult();
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You can read more about this pattern on the MongoDB documentation page Trees in MongoDB in the Child Links section.

Array of Ancestors

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<?php

#[MappedSuperclass]
class BaseCategory
{
    #[Field(type: 'string')]
    private string $name;

    // ...
}

#[Document]
class Category extends BaseCategory
{
    #[Id]
    private string $id;

    /** @var Collection<Category> */
    #[ReferenceMany(targetDocument: Category::class)]
    #[Index]
    private Collection $ancestors;

    /** @var Collection<Category> */
    #[ReferenceOne(targetDocument: Category::class)]
    #[Index]
    private ?Category $parent = null;

    // ...
}

#[EmbeddedDocument]
class SubCategory extends BaseCategory
{
}
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Query for all descendants of a category:

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<?php

$categories = $dm->createQueryBuilder(Category::class)
    ->field('ancestors.id')->equals('theid')
    ->getQuery()
    ->execute();
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Query for all ancestors of a category:

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<?php

$category = $dm->createQuery(Category::class)
    ->field('id')->equals('theid')
    ->getQuery()
    ->getSingleResult();

$ancestors = $category->getAncestors();
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You can read more about this pattern on the MongoDB documentation page Trees in MongoDB in the Array of Ancestors section.

Materialized Paths

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<?php

#[Document]
class Category
{
    #[Id]
    private string $id;

    #[Field(type: 'string')]
    private string $name;

    #[Field(type: 'string')]
    private string $path;

    // ...
}
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Query for the entire tree:

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<?php

$categories = $dm->createQuery(Category::class)
    ->sort('path', 'asc')
    ->getQuery()
    ->execute();
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Query for the node 'b' and all its descendants:

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<?php
$categories = $dm->createQuery(Category::class)
    ->field('path')->equals('/^a,b,/')
    ->getQuery()
    ->execute();
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You can read more about this pattern on the MongoDB documentation page Trees in MongoDB in the Materialized Paths (Full Path in Each Node) section.