One row of a conceptRows answer: a map from variable name to concept.
Rows implement Access, so a variable can be read directly:
row["person"]
#=> %TypeDB.Concept.Entity{iid: "0x1e0...", type: %TypeDB.Concept.EntityType{label: "person"}}
get_in(row, ["name"])
#=> %TypeDB.Concept.Attribute{value: "Alice", value_type: "string"}A variable bound to nothing yields nil, which is indistinguishable from an
absent variable through Access. Use fetch/2 when the difference matters.
involved_blocks is populated only when the query ran with
include_query_structure: true; it lists the ids of the query blocks that
produced this row.
Summary
Functions
Fetches a variable, distinguishing "bound to nothing" from "not present".
Returns a variable's concept, or default when it is absent or unbound.
Returns the row as a plain map of variable name to wire value.
Returns the natively typed value of a variable. See TypeDB.Concept.typed_value/1.
Returns the wire value of a variable bound to an attribute or value.
Returns the variable names bound in this row.
Types
@type t() :: %TypeDB.ConceptRow{ data: %{optional(String.t()) => TypeDB.Concept.entry()}, involved_blocks: [non_neg_integer()] | nil }
Functions
@spec fetch(t(), String.t()) :: {:ok, TypeDB.Concept.entry()} | :error
Fetches a variable, distinguishing "bound to nothing" from "not present".
{:ok, nil} # the variable exists but matched nothing
:error # the variable is not in this row@spec get(t(), String.t(), term()) :: TypeDB.Concept.entry() | term()
Returns a variable's concept, or default when it is absent or unbound.
Returns the row as a plain map of variable name to wire value.
The keys are strings — the query's own variable names, exactly as TypeDB sent them back.
That matters if you are reaching for Kernel.struct/2, which ignores keys
that are not atoms naming a field: handed a string-keyed map it returns the
struct's defaults and reports nothing, so the conversion silently produces a
struct full of nils. Convert the keys first:
row
|> TypeDB.ConceptRow.to_map()
|> Map.new(fn {variable, value} -> {String.to_existing_atom(variable), value} end)
|> then(&struct(Person, &1))String.to_existing_atom/1 rather than String.to_atom/1 so a query variable
cannot grow the atom table; the struct's own fields already exist as atoms
wherever Person is loaded. It raises ArgumentError for a variable that
does not name one, which is the failure you want over a silent nil.
Returns the natively typed value of a variable. See TypeDB.Concept.typed_value/1.
Returns the wire value of a variable bound to an attribute or value.
Returns the variable names bound in this row.