View Source Ash.Policy.FilterCheck behaviour (ash v2.9.25)

A type of check that is represented by a filter statement

That filter statement can be templated, currently only supporting {:_actor, field} which will replace that portion of the filter with the appropriate field value from the actor and {:_actor, :_primary_key} which will replace the value with a keyword list of the primary key fields of an actor to their values, like [id: 1]. If the actor is not present {:_actor, field} becomes nil, and {:_actor, :_primary_key} becomes false.

You can customize what the "negative" filter looks like by defining reject/1. This is important for filters over related data. For example, given an owner relationship and a data layer like ash_postgres where column != NULL does not evaluate to true (see postgres docs on NULL for more):

# The opposite of
` == 1`
# in most cases is not
`not( == 1)`
# because in postgres that would be `NOT ( = NULL)` in cases where there was no owner
# A better opposite would be
` != 1 or is_nil(`
# alternatively
`not( == 1) or is_nil(`

By being able to customize the reject filter, you can use related filters in your policies. Without it, they will likely have undesired effects.

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@type options() :: Keyword.t()

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View Source (optional)
@callback filter(options()) :: Keyword.t() | Ash.Expr.t()
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View Source (optional)
@callback reject(options()) :: Keyword.t() | Ash.Expr.t()

Link to this section Functions

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