Working with Views

Fenl expressions can be shared and re-used by creating a view. A view is a named expression. In subsequent Fenl expressions, the view's name is synonymous with the view's expression. Views are persisted in the Kaskada platform and are accessible to any query.

All methods on this page use from the view object. Be sure to import it before running any method:

from kaskada import view

View Methods

Creating a View

To create a view, we'll start by describing the expression we'd like to name. In this case, we're interested in some purchase statistics for each user. This definition depends on business logic and might require some iteration to get just right.

ℹ️

Idiomatic Kaskada

We like to use CamelCase for view names. This is the same naming convention as we use for tables, and helps to communicate that we're referring to a persistent resource in the Kaskada system, as opposed to a temporary local value created as part of a query.

Using fenlmagic

%%fenl --var purchase_stats
{
    time: Purchase.purchase_time,
    entity: Purchase.customer_id,
    max_amount: Purchase.amount | max(),
    min_amount: Purchase.amount | min(),
}

Notice that we added --var purchase_stats to the beginning of the magic block; this causes the extension to assign the query string to the variable purchase_stats when the block is run.

We can use this variable to create a view using the Python client without re-typing the expression:

view.create_view(
    view_name = "PurchaseStats",
    expression = purchase_stats,
)

Using python

Views can also be created without using fenlmagic:

view.create_view(
    view_name = "PurchaseStats",
    expression = "{
        time: Purchase.purchase_time,
        entity: Purchase.customer_id,
        max_amount: Purchase.amount | max(),
        min_amount: Purchase.amount | min(),
    }"
)

List Views

The list views method returns all views defined for your user. An optional search string can filter the response set.

Here is an example of listing tables:

view.list_views("Purchase")

Get View

You can get a view using its name:

view.get_view("PurchaseStats")

Updating a View

Views are currently immutable. Updating a view requires deleting that view and then re-creating it with a new expression.

Deleting a view

You can delete a view using its name:

view.delete_view("PurchaseStats")