copy_out_response.go

Documentation: github.com/jackc/pgx/v5/pgproto3

     1  package pgproto3
     2  
     3  import (
     4  	"bytes"
     5  	"encoding/binary"
     6  	"encoding/json"
     7  	"errors"
     8  	"math"
     9  
    10  	"github.com/jackc/pgx/v5/internal/pgio"
    11  )
    12  
    13  type CopyOutResponse struct {
    14  	OverallFormat     byte
    15  	ColumnFormatCodes []uint16
    16  }
    17  
    18  func (*CopyOutResponse) Backend() {}
    19  
    20  // Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
    21  // type identifier and 4 byte message length.
    22  func (dst *CopyOutResponse) Decode(src []byte) error {
    23  	buf := bytes.NewBuffer(src)
    24  
    25  	if buf.Len() < 3 {
    26  		return &invalidMessageFormatErr{messageType: "CopyOutResponse"}
    27  	}
    28  
    29  	overallFormat := buf.Next(1)[0]
    30  
    31  	columnCount := int(binary.BigEndian.Uint16(buf.Next(2)))
    32  	if buf.Len() != columnCount*2 {
    33  		return &invalidMessageFormatErr{messageType: "CopyOutResponse"}
    34  	}
    35  
    36  	columnFormatCodes := make([]uint16, columnCount)
    37  	for i := 0; i < columnCount; i++ {
    38  		columnFormatCodes[i] = binary.BigEndian.Uint16(buf.Next(2))
    39  	}
    40  
    41  	*dst = CopyOutResponse{OverallFormat: overallFormat, ColumnFormatCodes: columnFormatCodes}
    42  
    43  	return nil
    44  }
    45  
    46  // Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
    47  func (src *CopyOutResponse) Encode(dst []byte) ([]byte, error) {
    48  	dst, sp := beginMessage(dst, 'H')
    49  
    50  	dst = append(dst, src.OverallFormat)
    51  
    52  	if len(src.ColumnFormatCodes) > math.MaxUint16 {
    53  		return nil, errors.New("too many column format codes")
    54  	}
    55  	dst = pgio.AppendUint16(dst, uint16(len(src.ColumnFormatCodes)))
    56  	for _, fc := range src.ColumnFormatCodes {
    57  		dst = pgio.AppendUint16(dst, fc)
    58  	}
    59  
    60  	return finishMessage(dst, sp)
    61  }
    62  
    63  // MarshalJSON implements encoding/json.Marshaler.
    64  func (src CopyOutResponse) MarshalJSON() ([]byte, error) {
    65  	return json.Marshal(struct {
    66  		Type              string
    67  		ColumnFormatCodes []uint16
    68  	}{
    69  		Type:              "CopyOutResponse",
    70  		ColumnFormatCodes: src.ColumnFormatCodes,
    71  	})
    72  }
    73  
    74  // UnmarshalJSON implements encoding/json.Unmarshaler.
    75  func (dst *CopyOutResponse) UnmarshalJSON(data []byte) error {
    76  	// Ignore null, like in the main JSON package.
    77  	if string(data) == "null" {
    78  		return nil
    79  	}
    80  
    81  	var msg struct {
    82  		OverallFormat     string
    83  		ColumnFormatCodes []uint16
    84  	}
    85  	if err := json.Unmarshal(data, &msg); err != nil {
    86  		return err
    87  	}
    88  
    89  	if len(msg.OverallFormat) != 1 {
    90  		return errors.New("invalid length for CopyOutResponse.OverallFormat")
    91  	}
    92  
    93  	dst.OverallFormat = msg.OverallFormat[0]
    94  	dst.ColumnFormatCodes = msg.ColumnFormatCodes
    95  	return nil
    96  }
    97
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