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Collection()

Learn: Collections

Access a collection by its name.

Signature

Collection(collection: String) => Any

Description

Accesses a collection by its name. You can chain collection name methods to the returned collection.

Errors

If you attempt to access a collection that doesn’t exist, Fauna returns a query runtime error with an invalid_argument error code and a 400 HTTP status code:

invalid_argument

error: invalid argument `collection`: No such user collection `Foo`.
at *query*:1:11
  |
1 | Collection("Foo")
  |           ^^^^^^^
  |

Comparison to <collectionName>

Calling Collection() is similar to accessing <collectionName> directly, except:

  • Collection() returns an Any value

  • <collectionName> is a Collection value

This difference only affects static typing, not runtime behavior. Both Collection() and <collectionName> support the same collection name methods.

In most cases, you should use <collectionName>. However, Collection() is useful if you need to iterate through a list of collection names. See Dynamically specify a collection name.

Parameters

Parameter Type Required Description

collection

String

true

Collection name.

Return value

Type Description

Any

The named collection. You can chain collection name methods to the returned collection.

Examples

Collection() returns an Any value. For example:

Collection("Product")

Returns an Any value:

Product

Difference with <collectionName>

Accessing <collectionName> directly returns a similar value, typed as a Collection. For example:

Product

Returns the Product Collection value:

Product

Method chaining

In most cases, you’ll chain other collection name methods to Collection(). For example:

let produce = Category.byName("produce").first()

Collection("Product").create({
  name: "zebra pinata",
  description: "Giant Zebra Pinata",
  price: 23_99,
  stock: 0,
  category: produce
})

Returns an Any value:

{
  id: "12345",
  coll: Product,
  ts: Time("2099-06-24T21:21:37.170Z"),
  name: "zebra pinata",
  description: "Giant Zebra Pinata",
  price: 2399,
  stock: 0,
  category: Category("789")
}

Dynamically specify a collection name

Use Collection() to dynamically specify collection names in a query.

For example, the following user-defined function (UDF) uses Collection() to pass a collection name as an argument:

// Accepts a collection name as an argument.
function getPriceLowtoHigh(collection) {
  // Uses `Collection()` to dynamically specify
  // the collection name.
  Collection(collection).sortedByPriceLowToHigh() {
    price,
    name,
    description
  }
}

The following query calls the function:

// Calls the `getPriceLowtoHigh()` UDF with
// a `Product` collection argument.
getPriceLowtoHigh("Product")

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