class PG::BasicTypeMapBasedOnResult
Simple set of rules for type casting common PostgreSQL types from Ruby to PostgreSQL.
OIDs of supported type casts are not hard-coded in the sources, but are retrieved from the PostgreSQL's pg_type table in ::new .
This class works equal to PG::BasicTypeMapForResults, but does not define decoders for the given result OIDs, but encoders. So it can be used to type cast field values based on the type OID retrieved by a separate SQL query.
PG::TypeMapByOid#build_column_map can be used to generate a result independent PG::TypeMapByColumn type map, which can subsequently be used to cast query bind parameters or put_copy_data fields.
Example:
conn.exec( "CREATE TEMP TABLE copytable (t TEXT, i INT, ai INT[])" ) # Retrieve table OIDs per empty result set. res = conn.exec( "SELECT * FROM copytable LIMIT 0" ) tm = basic_type_mapping.build_column_map( res ) row_encoder = PG::TextEncoder::CopyRow.new type_map: tm conn.copy_data( "COPY copytable FROM STDIN", row_encoder ) do |res| conn.put_copy_data ['a', 123, [5,4,3]] end
Public Class Methods
new(connection)
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# File lib/pg/basic_type_mapping.rb, line 302 def initialize(connection) @coder_maps = build_coder_maps(connection) # Populate TypeMapByOid hash with encoders @coder_maps.map{|f| f[:encoder].coders }.flatten.each do |coder| add_coder(coder) end end