# `locus_mmdb_metadata`
[🔗](https://github.com/g-andrade/locus/blob/2.3.15/src/locus_mmdb_metadata.erl#L24)

API for working with MMDB - metadata.

See [MaxMind DB File Format Specification](https://maxmind.github.io/MaxMind-DB/).

# `binary_format_version`

```erlang
-type binary_format_version() :: {2, locus_mmdb_data:uint16()}.
```

# `parse_or_validation_error`

```erlang
-type parse_or_validation_error() ::
          {marker_not_found, bitstring()} |
          {atom(), term(), list()} |
          {not_a_map, term()} |
          {incompatible_binary_format_version,
           {locus_mmdb_data_raw:uint16(), locus_mmdb_data_raw:uint16()}} |
          {invalid_binary_format_minor_version, term()} |
          {invalid_binary_format_major_version, term()} |
          {missing_metadata_keys, [unicode:unicode_binary(), ...]} |
          {invalid_node_count, locus_mmdb_data_raw:value()} |
          {missing_node_count, locus_mmdb_data_raw:map_()} |
          {invalid_record_size, locus_mmdb_data_raw:value()} |
          {missing_record_size, locus_mmdb_data_raw:map_()} |
          {invalid_ip_version, locus_mmdb_data_raw:value()} |
          {missing_ip_version, locus_mmdb_data_raw:map_()} |
          {invalid_database_type, locus_mmdb_data_raw:value()} |
          {missing_database_type, locus_mmdb_data_raw:map_()} |
          {languages_not_an_array, locus_mmdb_data_raw:value()} |
          {bad_languages,
           {language_number, pos_integer(), not_an_utf8_string, locus_mmdb_data_raw:value()}} |
          {description_not_a_map, locus_mmdb_data_raw:value()} |
          {bad_description,
           {for_language_code,
            unicode:unicode_binary(),
            {not_an_utf8_string, locus_mmdb_data_raw:value()}}}.
```

# `t`

```erlang
-type t() ::
          #{binary_format_version := binary_format_version(),
            node_count := locus_mmdb_data:uint32(),
            record_size := locus_mmdb_data:uint16(),
            ip_version := 4 | 6,
            database_type := locus_mmdb_data:utf8_string(),
            languages => [locus_mmdb_data:utf8_string()],
            build_epoch := locus_mmdb_data:uint64(),
            description => #{locus_mmdb_data:utf8_string() => locus_mmdb_data:utf8_string()},
            {'$_unrecognized_properties'} =>
                #{locus_mmdb_data:utf8_string() := locus_mmdb_data_raw:value()}}.
```

# `parse_and_validate`

```erlang
-spec parse_and_validate(EncodedDatabase) -> {ok, Metadata, TreeAndDataSection} | {error, Reason}
                            when
                                EncodedDatabase :: binary(),
                                Metadata :: t(),
                                TreeAndDataSection :: binary(),
                                Reason :: parse_or_validation_error().
```

Parses and validates `Metadata` out of `EncodedDatabase`.

To proceed further with `TreeAndDataSection`,
see `locus_mmdb:unpack_tree_data_and_data_section/2`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*