Patterns.Queryable.DSL (patterns v0.0.1)

Binding-aware query helpers for Patterns.Queryable.

This module extends Ecto query composition with two small pieces:

from/2, which supports binding/1 and binding/2 source patterns.
Binding inspection helpers for resolving named bindings to indexes and schema modules.

Most callers get from/2 through use Patterns.Queryable. The binding inspection helpers are used by Patterns.Queryable.Filters to resolve nested association filters from the current scoped binding.

Summary

Functions

binding_index(query, binding)

Returns the query binding index for a named binding.

binding_schema(query)

Returns the Ecto schema module for the current scoped query binding.

binding_schema(query, binding)

Returns the Ecto schema module for a named query binding or binding index.

from(expr, opts \\ [])

Extends Ecto.Query.from/2 with binding-aware query source patterns.

Functions

binding_index(query, binding)

Returns the query binding index for a named binding.

binding_index(from(post in Blog.Post, as: :post), :post)
#=> 0

binding_index(from(post in Blog.Post, as: :self), :self)
#=> 0

The unnamed root binding is index 0, but it is not addressable as :self unless the query was explicitly created with as: :self.

binding_index(from(post in Blog.Post), :self)
# raises ArgumentError, "query binding :self does not exist"

binding_index(from(post in Blog.Post), :missing)
# raises ArgumentError, "query binding :missing does not exist"

binding_schema(query)

Returns the Ecto schema module for the current scoped query binding.

binding_schema(from post in Blog.Post)
#=> Blog.Post

Raises ArgumentError when the current binding does not resolve to an Ecto schema source.

binding_schema(from post in "posts")
# raises ArgumentError, "root query binding must be an Ecto schema source"

binding_schema(query, binding)

Returns the Ecto schema module for a named query binding or binding index.

binding_schema(
  from(post in Blog.Post, join: comment in assoc(post, :comments), as: :comments),
  :comments
)
#=> Blog.Comment

binding_schema(
  from(post in Blog.Post, join: comment in assoc(post, :comments), as: :comments),
  1
)
#=> Blog.Comment

Raises ArgumentError when the binding does not exist or does not resolve to an Ecto schema source.

binding_schema(from(post in Blog.Post), :missing)
# raises ArgumentError, "query binding :missing does not exist"

binding_schema(from(post in Blog.Post), 2)
# raises ArgumentError, "query binding at index 2 does not exist"

from(expr, opts \\ [])

(macro)

Extends Ecto.Query.from/2 with binding-aware query source patterns.

This macro otherwise delegates to Ecto's from DSL unchanged. It exists so modules using Patterns.Queryable can write queries against either the root binding or a binding supplied by surrounding query composition.

Use binding/1 to target the current scoped binding, falling back to the root query binding:

from binding(entry) in query,
  where: entry.slug == ^slug

Use binding/2 to target an explicit named binding:

from binding(:references, reference) in query,
  where: reference.target_slug == ^slug