# Built-in functions ## [](#_concept_functions)Concept functions `iid(x)` Returns the internal ID of the provided instance argument as a string. The result is intended to be used in an `iid` predicate in future queries to uniquely identify the instance. `iid()` is mainly intended for use in `fetch` queries to uniquely identify the instance. It is not typically needed in other query types, as the IID is available directly in the result rows. ```typeql iid($x) == "0x1e0000000000000000001f" ``` `label(t)` Returns the label of the provided type argument as a string. ```typeql label($x) == "person" ``` ## [](#_documentation_fns)Documentation functions `get_doc(t)` Returns the documentation string of the provided type argument. If the type has no `@doc` annotation, an empty string is returned. ```typeql get_doc(person) == "This represents a person" ``` `get_owns_doc(owner, attribute)` Returns the documentation string of the provided `owns` if it exists. If the `owns` exists but has no `@doc` annotation, an empty string is returned. ```typeql get_owns_doc(person, name) == "The full legal name of the person" ``` `get_plays_doc(player, role)` Returns the documentation string of the provided `plays` if it exists. If the `plays` exists but has no `@doc` annotation, an empty string is returned. ```typeql get_plays_doc(person, friendship:friend) == "A person can be a friend" ``` `get_relates_doc(relation, role)` Returns the documentation string of the provided `relates` if it exists. If the `relates` exists but has no `@doc` annotation, an empty string is returned. ```typeql get_relates_doc(friendship, friendship:friend) == "A party in this friendship" ``` `get_sub_doc(sub, sup)` Returns the documentation string of the provided `sub` if it exists. If the `sub` exists but has no `@doc` annotation, an empty string is returned. ```typeql get_sub_doc(student, person) == "A person who is a student" ``` `get_fun_doc(function_name)` Returns the documentation string of the provided function if it exists. If the function exists but has no `@doc` annotation, an empty string is returned. ```typeql get_fun_doc("my_function") == "This is my custom function" ``` `get_struct_doc(struct_name)` Returns the documentation string of the provided struct if it exists. If the struct exists but has no `@doc` annotation, an empty string is returned. ```typeql get_struct_doc("my_struct") == "This is my custom struct" ``` `get_struct_field_doc(struct_name, field_name)` Returns the documentation string of the provided struct field if it exists. If the struct field exists but has no `@doc` annotation, an empty string is returned. ```typeql get_struct_field_doc("my_struct", "its_field") == "This is a field of my custom struct" ``` ## [](#_metadata_fns)Metadata functions `get_meta(key, t)` Returns the metadata of the provided type with the specified key. If the type has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_meta("icon", person) == ":silhouette.png" ``` `get_all_meta(t)` Returns all metadata of the provided type as a stream of key-value pairs. ```typeql let $key, $value in get_all_meta(person); $key == "icon" $value == ":silhouette.png" ``` `get_owns_meta(key, owner, attribute)` Returns the metadata of the provided `owns` with the specified key, if it exists. If the `owns` exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_owns_meta("color", person, name) == "#0088FF" ``` `get_owns_all_meta(owner, attribute)` Returns all metadata of the provided `owns` as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_owns_all_meta(person, name); $key == "color" $value == "#0088FF" ``` `get_plays_meta(key, player, role)` Returns the metadata of the provided `plays` with the specified key, if it exists. If the `plays` exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_plays_meta("color", person, friendship:friend) == "#00CC00" ``` `get_plays_all_meta(player, role)` Returns all metadata of the provided `plays` as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_plays_all_meta(person, friendship:friend); $key == "color" $value == "#00CC00" ``` `get_relates_meta(key, relation, role)` Returns the metadata of the provided `relates` with the specified key, if it exists. If the `relates` exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_relates_meta("color", friendship, friendship:friend) == "#0088FF" ``` `get_relates_all_meta(relation, role)` Returns all metadata of the provided `relates` as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_relates_all_meta(friendship, friendship:friend); $key == "color" $value == "#0088FF" ``` `get_sub_meta(key, sub, sup)` Returns the metadata of the provided `sub` with the specified key, if it exists. If the `sub` exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_sub_meta("arrow-style", student, person) == "dashed" ``` `get_sub_all_meta(sub, sup)` Returns all metadata of the provided `sub` as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_sub_all_meta(student, person); $key == "arrow-style" $value == "dashed" ``` `get_fun_meta(key, function_name)` Returns the metadata of the provided function with the specified key, if it exists. If the function exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_fun_meta("category", "my_function") == "utility" ``` `get_fun_all_meta(function_name)` Returns all metadata of the provided function as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_fun_all_meta("my_function"); $key == "category" $value == "utility" ``` `get_struct_meta(key, struct_name)` Returns the metadata of the provided struct with the specified key, if it exists. If the struct exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_struct_meta("version", "my_struct") == "1.0" ``` `get_struct_all_meta(struct_name)` Returns all metadata of the provided struct as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_struct_all_meta("my_struct"); $key == "version" $value == "1.0" ``` `get_struct_field_meta(key, struct_name, field_name)` Returns the metadata of the provided struct field with the specified key, if it exists. If the struct field exists but has no `@meta` annotation with the specified key, an empty string is returned. ```typeql get_struct_field_meta("description", "my_struct", "its_field") == "A field description" ``` `get_struct_field_all_meta(struct_name, field_name)` Returns all metadata of the provided struct field as a stream of key-value pairs, if it exists. ```typeql let $key, $value in get_struct_field_all_meta("my_struct", "its_field"); $key == "description" $value == "A field description" ``` [Function calls](../function-calls/index.md) [Structs](../structs/index.md) [Edit on GitHub](https://github.com/typedb/typedb-docs/edit/3.x-development/typeql-reference/modules/ROOT/pages/expressions/builtin-functions.adoc) Edit this page on GitHub.