phpman > man > MongoDB::DataTypes(3pm)

NAME
    MongoDB::DataTypes - Using MongoDB data types with Perl

VERSION
    version v2.2.2

DESCRIPTION
    MongoDB stores typed data in a data format called BSON (<http://bsonspec.org/>). This document
    describes how to work with BSON data types in the MongoDB Perl driver.

    As of the MongoDB Perl driver v2.0.0, the driver relies on the external BSON library (and
    optional BSON::XS library) for converting between Perl data and the MongoDB BSON format.

  Additional information
    Additional information about MongoDB documents and types may be found in the following MongoDB
    manual pages:

    *   Documents <https://docs.mongodb.com/manual/core/document/>

    *   BSON Types <https://docs.mongodb.com/manual/reference/bson-types/>

ESSENTIAL CONCEPTS
  MongoDB records are ordered documents
    A MongoDB record (i.e. "row") is a BSON document -- a list of key-value pairs, like a Perl hash
    except that the keys in a BSON document are ordered. Keys are always strings. Values can be any
    of 20+ BSON types.

    Queries and update specifications are also expressed as documents.

  Type wrapper classes provide non-native and disambiguated types
    In order to represent BSON types that don't natively exist in Perl, we use type wrapper classes
    from the BSON library, such as BSON::OID and BSON::Time.

    Wrappers for native types are available when necessary to address limitations in Perl's type
    system. For example, one can use BSON::Doc for a ordered hash or BSON::Int64 for a 64-bit
    integer.

    The BSON class has attributes that configure how type wrappers are used during encoding and
    decoding.

    The PERL-BSON Type Mapping documentation has a detailed table of all BSON type conversions.

  String/number type conversion heuristics
    Perl's scalar values can have several underlying, internal representations such as double,
    integer, or string (see perlguts). When encoding to BSON, the default behavior is as follows:

    *   If the value has a valid double representation, it will be encoded to BSON as a double.

    *   Otherwise, if the value has a valid integer interpretation, it will be encoded as either
        Int32 or Int64; the smallest type that the value fits will be used; a value that overflows
        will error.

    *   Otherwise, the value will be encoded as a UTF-8 string.

    The BSON library provides the "prefer_numeric" attribute to more aggressively coerce number-like
    strings that don't already have a numeric representation into a numeric form.

  Order sometimes matters a lot
    When writing a query document, the order of top level keys doesn't matter, but the order of keys
    in any embedded documents does matter.

        $coll->insert_one({
            name => { first => "John", last => "Doe" },
            age => 42,
            color => "blue",
        });

        # Order doesn't matter here
        $coll->find( { age => 42, color => "blue" } );     # MATCH
        $coll->find( { color => "blue", age => 42 } );     # MATCH

        # Order *does* matter here
        $coll->find(
            { name => { first => "John", last => "Doe" } } # MATCH
        );
        $coll->find(
            { name => { last => "Doe", first => "John" } } # NO MATCH
        );

    When specifying a sort order or the order of keys for an index, order matters whenever there is
    more than one key.

    Because of Perl's hash order randomization, be very careful using native hashes with MongoDB.
    See the "Documents" section below for specific guidance.

THE BSON::TYPES LIBRARY
    BSON::Types is a library with helper subroutines to easily create BSON type wrappers. Use of
    this library is highly recommended.

        use BSON::Types ':all';

        $int64   = bson_int64(42);         # force encoding more bits
        $decimal = bson_decimal("24.01");  # Decimal128 type
        $time    = bson_time();            # now

    Examples in the rest of this document assume that all BSON::Types helper functions are loaded.

NOTES ON SPECIFIC TYPES
  Arrays
    BSON arrays encode and decode via Perl array references.

  Documents
    Because Perl's hashes guarantee key-order randomness, using hash references as documents will
    lead to BSON documents with a different key order. For top-level keys, this shouldn't cause
    problems, but it may cause problems for embedded documents when querying, sorting or indexing on
    the embedded document.

    For sending data to the server, the BSON::Doc class provides a very lightweight wrapper around
    ordered key-value pairs, but it's opaque.

        $doc = bson_doc( name => "Larry", color => "purple" );

    You can also use Tie::IxHash for a more-interactive ordered document, but at the expense of
    tied-object overhead.

    The BSON encoder has an "ordered" attribute that, if enabled, returns all documents as
    order-preserving tied hashes. This is slow, but is the only way to ensure that documents can
    roundtrip preserving key order.

  Numbers
    By default, the BSON decoder decodes doubles and integers into a Perl-native form. To maximize
    fidelity during a roundtrip, the decoder supports the wrap_numbers attribute to always decode to
    a BSON type wrapper class with numeric overloading.

   32-bit Platforms
    On a 32-bit platform, the BSON library treats Math::BigInt as the "native" type for integers
    outside the (signed) 32-bit range. Values that are encoded as 64-bit integers will be decoded as
    Math::BigInt objects.

   64-bit Platforms
    On a 64-bit platform, (signed) Int64 values are supported, but, by default, numbers will be
    stored in the smallest BSON size needed. To force a 64-bit representation for numbers in the
    signed 32-bit range, use a type wrapper:

        $int64 = bson_int64(0); # 64 bits of 0

   Long doubles
    On a perl compiled with long-double support, floating point number precision will be lost when
    sending data to MongoDB.

   Decimal128
    MongoDB 3.4 adds support for the IEEE 754 Decimal128 type. The BSON::Decimal128 class is used as
    a proxy for these values for both inserting and querying documents. Be sure to use strings when
    constructing Decimal128 objects.

        $item = {
            name => "widget",
            price => bson_decimal128("4.99"), # 4.99 as a string
            currency => "USD",
        };

        $coll->insert_one($item);

  Strings
    String values are expected to be character-data (not bytes). They are encoded as UTF-8 before
    being sent to the database and decoded from UTF-8 when received. If a string can't be decoded,
    an error will be thrown.

    To save or query arbitrary, non-UTF8 bytes, use a binary type wrapper (see "Binary Data",
    below).

  Booleans
    Boolean values are emulated using the boolean package via the "boolean::true" and
    "boolean::false" functions. Using boolean objects in documents will ensure the documents have
    the BSON boolean type in the database. Likewise, BSON boolean types in the database will be
    returned as boolean objects.

    An example of inserting boolean values:

        use boolean;

        $collection->insert_one({"okay" => true, "name" => "fred"});

    An example of using boolean values for query operators (only returns documents where the name
    field exists):

        $cursor = $collection->find({"name" => {'$exists' => true}});

    Often, you can just use 1 or 0 in query operations instead of "true" and "false", but some
    commands require boolean objects and the database will return an error if integers 1 or 0 are
    used.

    Boolean objects from the following JSON libraries will also be encoded correctly in the
    database:

    *   JSON::XS

    *   JSON::PP

    *   Cpanel::JSON::XS

    *   Mojo::JSON

    *   JSON::Tiny

  Object IDs
    The BSON object ID type (aka "OID") is a 12 byte identifier that ensures uniqueness by mixing a
    timestamp and counter with host and process-specific bytes.

    All MongoDB documents have an "_id" field as a unique identifier. This field does not have to be
    an object ID, but if the field does not exist, an object ID is created automatically for it when
    the document is inserted into the database.

    The BSON::OID class is the type wrapper for object IDs.

    To create a unique id:

        $oid = bson_oid();

    To create a BSON::OID from an existing 24-character hexadecimal string:

        $oid = bson_oid("123456789012345678901234");

  Regular Expressions
    Use "qr/.../" to use a regular expression in a query, but be sure to limit your regular
    expression to syntax and features supported by PCRE, which are not fully compatible with Perl
    <https://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expressions#Differences_from_Perl>.

        $cursor = $collection->find({"name" => qr/[Jj]oh?n/});

    Regular expressions will match strings saved in the database.

    NOTE: only the following flags are supported: "imsxlu".

    You can also save and retrieve regular expressions themselves, but regular expressions will be
    retrieved as BSON::Regex objects for safety (these will round-trip correctly).

    From that object, you can attempt to compile a reference to a "qr{}" using the "try_compile"
    method. However, due to PCRE differences, this could fail to compile or could have different
    match behavior than intended.

        $collection->insert_one({"regex" => qr/foo/i});
        $obj = $collection->find_one;
        if ("FOO" =~ $obj->{regex}->try_compile) { # matches
            print "hooray\n";
        }

    SECURITY NOTE: A regular expression can evaluate arbitrary code if "use re 'eval'" is in scope.
    You are strongly advised never to use untrusted input as a regular expression.

  Dates
    BSON has a datetime type representing signed Int64 milliseconds relative to the Unix epoch. As
    of MongoDB v2.0.0, the lightweight BSON::Time wrapper is now the default wrapper for datetime
    data.

    The "bson_time()" helper function uses fractional epoch seconds, for better integration with the
    Time::HiRes module:

        use Time::HiRes 'time';

        $later = bson_time( time() + 60 );

    For convenience, The default value for the helper is "Time::HiRes::time":

        $now = bson_time();

    BSON::Time has methods for inflating into various popular Perl date classes, including DateTime,
    Time::Moment and DateTime::Tiny. The BSON encoder can also encode objects of these types, with
    limitations on precision and timezone based on the underlying class. For example, DateTime::Tiny
    has no time zone or sub-second precision.

  Binary Data
    By default, all database strings are UTF-8. To store images, binaries, and other non-UTF-8 data,
    one can use the BSON binary data type via the BSON::Bytes wrapper.

    The BSON binary type includes the notion of a "subtype" attribute, which can be any integer
    between 0 and 255. The meaning of subtypes from 0 to 127 are reserved for definition by MongoDB;
    values 128 to 255 are user-defined. Binary data values will only match in a MongoDB query if
    both the binary bytes and the subtypes are the same. The default subtype is 0 (a.k.a. "generic
    binary data") and generally should not be modified.

    To roundtrip binary data, use the BSON::Bytes wrapper:

        # non-utf8 string
        $bytes = "\xFF\xFE\xFF";

        $collection->insert_one({"photo" => bson_bytes($bytes)});

    Binary data will be decoded into a BSON::Bytes object. It stringifies as the underlying bytes
    for convenience.

    One can also store binary data by using a string reference.

        $collection->insert_one({"photo" => \$bytes});

  MinKey and MaxKey
    BSON::MinKey is "less than" any other value of any type. This can be useful for always returning
    certain documents first.

    BSON::MaxKey is "greater than" any other value of any type. This can be useful for always
    returning certain documents last.

    There is a helper function for each:

        $min = bson_minkey();
        $max = bson_maxkey();

AUTHORS
    *   David Golden <david AT mongodb.com>

    *   Rassi <rassi AT mongodb.com>

    *   Mike Friedman <friedo AT friedo.com>

    *   Kristina Chodorow <k.chodorow AT gmail.com>

    *   Florian Ragwitz <rafl AT debian.org>

COPYRIGHT AND LICENSE
    This software is Copyright (c) 2020 by MongoDB, Inc.

    This is free software, licensed under:

      The Apache License, Version 2.0, January 2004