com.github.mauricio.async.db.postgresql.parsers.RowDescriptionParser.scala Maven / Gradle / Ivy

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/*
 * Copyright 2013 Maurício Linhares
 *
 * Maurício Linhares licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package com.github.mauricio.async.db.postgresql.parsers

import com.github.mauricio.async.db.postgresql.messages.backend.{
  RowDescriptionMessage,
  PostgreSQLColumnData,
  ServerMessage
}
import com.github.mauricio.async.db.util.ByteBufferUtils
import java.nio.charset.Charset
import io.netty.buffer.ByteBuf

/**
 * RowDescription (B) Byte1('T') Identifies the message as a row description.
 *
 * Int32 Length of message contents in bytes, including self.
 *
 * Int16 Specifies the number of fields in a row (can be zero).
 *
 * Then, for each field, there is the following:
 *
 * String The field name.
 *
 * Int32 If the field can be identified as a column of a specific table, the
 * object ID of the table; otherwise zero.
 *
 * Int16 If the field can be identified as a column of a specific table, the
 * attribute number of the column; otherwise zero.
 *
 * Int32 The object ID of the field's data type.
 *
 * Int16 The data type size (see pg_type.typlen). Note that negative values
 * denote variable-width types.
 *
 * Int32 The type modifier (see pg_attribute.atttypmod). The meaning of the
 * modifier is type-specific.
 *
 * Int16 The format code being used for the field. Currently will be zero (text)
 * or one (binary). In a RowDescription returned from the statement variant of
 * Describe, the format code is not yet known and will always be zero.
 */
class RowDescriptionParser(charset: Charset) extends MessageParser {

  override def parseMessage(b: ByteBuf): ServerMessage = {

    val columnsCount = b.readShort()
    val columns      = new Array[PostgreSQLColumnData](columnsCount)

    0.until(columnsCount).foreach { index =>
      columns(index) = new PostgreSQLColumnData(
        name = ByteBufferUtils.readCString(b, charset),
        tableObjectId = b.readInt(),
        columnNumber = b.readShort(),
        dataType = b.readInt(),
        dataTypeSize = b.readShort(),
        dataTypeModifier = b.readInt(),
        fieldFormat = b.readShort()
      )
    }

    new RowDescriptionMessage(columns)
  }

}