Protocol::CassandraCQL::ColumnMeta - stores the column metadata of a Cassandra CQL query
Objects in this class interpret the column metadata from a message frame containing a
OPCODE_RESULT response to a query giving
RESULT_PREPARED. It provides lookup of column names and type information, and provides a convenient accessor to the encoding and decoding support functions, allowing encoding of bytestrings from perl data when executing a prepared statement, and decoding of bytestrings to perl data when obtaining query results.
It is also subclassed as Protocol::CassandraCQL::Result.
$meta = Protocol::CassandraCQL::ColumnMeta->from_frame( $frame )
Returns a new column metadata object initialised from the given message frame.
$meta = Protocol::CassandraCQL::ColumnMeta->new( %args )
Returns a new column metadata object initialised directly from the given column data. This constructor is intended for use by unit test scripts, to create metadata directly from mocked connection objects or similar.
It takes the following named arguments:
- columns => ARRAY[ARRAY[STR, STR, STR, STR]]
An ARRAY reference containing the data about individual columns. Each row is represented by an ARRAY reference containing four strings; giving the three components of its name, and the name of its type:
[ $keyspace, $table, $column, $typename ]
$n = $meta->columns
Returns the number of columns
$name = $meta->column_name( $idx )
( $keyspace, $table, $column ) = $meta->column_name( $idx )
Returns the name of the column at the given (0-based) index; either as three separate strings, or all joined by ".".
$name = $meta->column_shortname( $idx )
Returns the short name of the column; which will be just the column name unless it requires the table or keyspace name as well to make it unique within the set.
$type = $meta->column_type( $idx )
Returns the type of the column at the given index as an instance of Protocol::CassandraCQL::Type.
$idx = $meta->find_column( $name )
Returns the index of the given named column. The name may be given as
column if they are unique within the set. Returns
undef if no such column exists.
@bytes = $meta->encode_data( @data )
Returns a list of encoded bytestrings from the given data according to the type of each column. Checks each value is valid; if not throws an exception explaining which column failed and why.
An exception is thrown if the wrong number of values is passed.
@data = $meta->decode_data( @bytes )
Returns a list of decoded data from the given encoded bytestrings according to the type of each column.
This code was paid for by
Paul Evans <email@example.com>