relations-handling.md

Handling Relations

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

Alice also allows you to directly reference objects' properties using the @name->property notation.

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 entities' ID but you will then have to split fixtures in multiple files (this is because objects are persisted at the end of each file processing) :

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

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

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.

There is one limitation, you can only refer to objects that are defined above in the file. If you want to use an existing object that is already present in your database you can also provide the id of the object. For this to work however the setter method for that property must have a type hint.

Nelmio\Entity\Group:
    group1:
        owner: 1 # this will try to fetch the User (as typehinted in Group::setOwner) with id 1

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

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

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

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 object 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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