fixture-riveter

Relations

Just as databases can define relationships between tables, so can we define relationships between fixtures. In Objection.js, these are called "Relations"; in Rails, they're called "Associations". Here, we call them Relations.

Regardless of how it's defined, the relation doesn't change what happens when the given fixture generates a new instance: the related fixture is generated with the given strategy (by default, the same strategy as the initial instance), and then is set on the property.

Then, relating the two instances beyond setting the property (for example, setting postId) will use the relate function in the chosen adapter, allowing for each ORM to bind the two instances as they need. This removes the need to define postId foreign key attributes in fixtures.

Fixture name matches attribute

When defining a relation, if the attribute's name is the same as the related fixture, it can be defined implicitly like a normal attribute or explicitly with the relate function:

fr.fixture("user", User, (f) => {
    f.attr("post");
    // or
    f.post();
    // or
    f.relation("post");
    // or
    f.attr("post", async(e) => e.relation("post"));
});
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Fixture name doesn't match attribute

If, however, the related fixture does not match the attribute, you need to specify the fixture explicitly:

fr.fixture("user", User, (f) => {
    f.relation("post", {fixture: "blog"});
    // or same as above but changing the relation name to match other fixture
    f.attr("post", async(e) => e.relation("blog"));
    // or
    f.post(async(e) => e.relation("blog"));
});
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Overriding attributes

Just like overriding attributes when calling a strategy method, you can pass in an object of attributes to set on the related fixture.

fr.fixture("user", User, (f) => {
    f.attr("post", {title: "New post"});
    // or
    f.post({title: "New post"});
    // or
    f.relation("post", {title: "New post"});
    // or
    f.attr("name", () => "Noah");
    f.attr("post", async(e) => e.relation("post", {title: await e.attr("name")}));
});
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