Concord.Index.Extractor (Concord v2.0.0)

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Declarative index extractor specifications.

All specs are plain data (tuples of atoms/binaries/integers) — no anonymous functions. This makes them safe to serialize in the Raft log and snapshots across code versions without risk of :badfun errors.

Supported Specs

  • {:map_get, key} — Extract a single map key
  • {:nested, [key1, key2, ...]} — Extract a nested value via get_in/2
  • {:identity} — Index the entire value as-is
  • {:element, n} — Extract the nth element from a tuple

Examples

# Index on user email field
{:map_get, :email}

# Index on nested field
{:nested, [:address, :city]}

# Index on the raw value
{:identity}

Summary

Types

spec()

Functions

extract(extractor, value)

Extracts an index value from a stored value using the given spec.

index_value(table, key, value, spec)

Indexes a value in the given ETS table using the extractor spec. Handles single values and lists of values.

remove_from_index(table, key, old_value, spec)

Removes a value from the index ETS table using the extractor spec.

valid?(f)

Validates that a given term is a supported extractor spec.

Types

spec()

@type spec() ::
  {:map_get, atom() | binary()}
  | {:nested, [atom() | binary()]}
  | {:identity}
  | {:element, non_neg_integer()}

Functions

extract(extractor, value)

@spec extract(spec(), term()) :: term() | nil

Extracts an index value from a stored value using the given spec.

Returns nil if extraction fails or the field doesn't exist.

index_value(table, key, value, spec)

@spec index_value(atom(), binary(), term(), spec()) :: :ok

Indexes a value in the given ETS table using the extractor spec. Handles single values and lists of values.

remove_from_index(table, key, old_value, spec)

@spec remove_from_index(atom(), binary(), term(), spec()) :: :ok

Removes a value from the index ETS table using the extractor spec.

valid?(f)

@spec valid?(term()) :: boolean()

Validates that a given term is a supported extractor spec.