Arc.Context (cratis_arc v0.1.0)

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Request-scoped facts handed to every command, query, validator and policy.

Arc has no dependency injection container. Handlers call Repo, context modules and Chronicle directly, and receive the caller's facts through this struct. The same values are set as Logger metadata while the artifact runs (:arc_correlation_id, :arc_tenant).

  • :application - the Arc.Application module running the artifact
  • :principal - the Arc.Principal of the caller
  • :tenant - the resolved tenant, or nil
  • :correlation_id / :causation_id - tracing identifiers (correlation is echoed on the response)
  • :metadata - free-form map; copied to the Chronicle append as causation properties
  • :deadline - monotonic millisecond deadline, or nil
  • :provided - values returned by the command's provide/2
  • :allowed_severity - the highest non-blocking validation severity the caller accepts
  • :chronicle - options passed to every Chronicle.append/3 (for example client:); for a named tenant it carries that tenant as the Chronicle namespace:
  • :query - while a query runs, what the caller asked for: %{page:, page_size:, sort_by:, sort_direction:} (sort_by is the camelCase wire name). A query that pages in the database reads it, for example Arc.MongoDB.page/3

Summary

Types

t()

Functions

expired?(context)

Whether the deadline, if any, has passed.

new(opts \\ [])

Builds a context, generating a correlation id when none is given.

new_correlation_id()

Generates a canonical lowercase UUID v4 string.

Types

t()

@type t() :: %Arc.Context{
  allowed_severity: integer(),
  application: module() | nil,
  causation_id: String.t() | nil,
  chronicle: keyword(),
  correlation_id: String.t() | nil,
  deadline: integer() | nil,
  metadata: map(),
  principal: Arc.Principal.t(),
  provided: map(),
  query: map(),
  tenant: String.t() | nil
}

Functions

expired?(context)

@spec expired?(t()) :: boolean()

Whether the deadline, if any, has passed.

new(opts \\ [])

@spec new(keyword()) :: t()

Builds a context, generating a correlation id when none is given.

new_correlation_id()

@spec new_correlation_id() :: String.t()

Generates a canonical lowercase UUID v4 string.