relations-handling.md

Handling Relations

1. References
2. Multiple References
3. Self reference
4. Passing references to providers

References

Let's get back to the Group. Ideally a group should have members, and Alice allows you to reference one object from another one. You can do that with the @name notation, where name is a fixture name from any class.

Let's add a fixed owner to the group:

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group1:
        name: Admins
        owner: '@user1'

Warning: References (e.g. here group1) should always be composed of letters, digits, periods (.), underscores (_) and slashes (/). Other characters such as {, }, (, ) are still allowed but hold a special meaning (e.g. for ranged fixtures).

Alice also allows you to directly reference objects' properties using the @name->property notation or calling an object method @name->getProperty().

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group1:
        name: Admins
        owner: '@user1->username'

To be able to use this feature, your entities have to match some requirements :

• You can reference public properties
• You can reference properties reachable through a getter (i.e : @name->property will call $name->getProperty() if property is not public)
• You can reference private properties by decorating the property accessor with the ReflectionPropertyAccessor
• You can reference entities' ID :

# fixture_user.yml
Nelmio\Entity\User:
    # ...

# fixture_group.yml
Nelmio\Entity\Group:
    group1:
        name: Admins
        owner: '@user1->id'

Warning: If you are using IDs this way, this either means you are setting the IDs when your object is created like with UUIDs or you will not have any guarantee the ID is not already used in the database.

If you want to create ten users and ten groups and have each user own one group, you can use <current()> which is replaced with the current ID of each iteration when using fixture ranges:

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group{1..10}:
        owner: '@user<current()>'

If you would like a random user instead of a fixed one, you can define a reference with a wildcard:

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group1:
        name: Admins
        owner: '@user*'

It will then pick any object whose name matches user* where * can be any string.

It is also possible to create a relation to a random object by id:

Nelmio\Entity\Group:
    group1:
        owner: '@user<numberBetween(1, 200)>'

Note: To create a string @foo that is not a reference you can escape it as \@foo

Note: When @ is used in the middle of a word, e.g. [email protected], it will be automatically escaped.

Multiple References

If we also want to add group members, there are two ways to do this. One is to define an array of references to have a fixed set of members:

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group1:
        name: Admins
        owner: '@user1'
        members: ['@user2', '@user3']

Another, which is more interesting, is to define a reference with a wildcard, and also tell Alice how many objects you want:

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group1:
        name: Admins
        owner: '@user1'
        members: '5x @user*'

In this case it will pick 5 fixture objects which have a name matching user*.

You can also randomize the amount by combining it with faker data:

    # ...
        members: '<numberBetween(1, 10)>x @user*'

If the data needs to be static instead, you can use the same syntax as the one used for fixtures range.

Nelmio\Entity\User:
    # ...

Nelmio\Entity\Group:
    group{1..10}:
        members: '@user{1..10}'

Note: You do not need to define multi-references inside an array, since they are automatically translated to an array of objects.

Self reference

The @self reference is assigned to the current fixture instance.

Passing references to providers

You can pass references to providers much like you can pass variables:

Nelmio\Entity\Group:
    group1:
        owner: '<numberBetween(1, 200)>'

    group2:
        owner: '<numberBetween(@group1->owner, 200)>'

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