gtsocial-umbx

extended_query_builder.go (6166B)

---

 package pgx
 
 import (
 	"database/sql/driver"
 	"fmt"
 
 	"github.com/jackc/pgx/v5/internal/anynil"
 	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
 // ExtendedQueryBuilder is used to choose the parameter formats, to format the parameters and to choose the result
 // formats for an extended query.
 type ExtendedQueryBuilder struct {
 	ParamValues     [][]byte
 	paramValueBytes []byte
 	ParamFormats    []int16
 	ResultFormats   []int16
 }
 
 // Build sets ParamValues, ParamFormats, and ResultFormats for use with *PgConn.ExecParams or *PgConn.ExecPrepared. If
 // sd is nil then QueryExecModeExec behavior will be used.
 func (eqb *ExtendedQueryBuilder) Build(m *pgtype.Map, sd *pgconn.StatementDescription, args []any) error {
 	eqb.reset()
 
 	anynil.NormalizeSlice(args)
 
 	if sd == nil {
 		return eqb.appendParamsForQueryExecModeExec(m, args)
 	}
 
 	if len(sd.ParamOIDs) != len(args) {
 		return fmt.Errorf("mismatched param and argument count")
 	}
 
 	for i := range args {
 		err := eqb.appendParam(m, sd.ParamOIDs[i], -1, args[i])
 		if err != nil {
 			err = fmt.Errorf("failed to encode args[%d]: %v", i, err)
 			return err
 		}
 	}
 
 	for i := range sd.Fields {
 		eqb.appendResultFormat(m.FormatCodeForOID(sd.Fields[i].DataTypeOID))
 	}
 
 	return nil
 }
 
 // appendParam appends a parameter to the query. format may be -1 to automatically choose the format. If arg is nil it
 // must be an untyped nil.
 func (eqb *ExtendedQueryBuilder) appendParam(m *pgtype.Map, oid uint32, format int16, arg any) error {
 	if format == -1 {
 		preferredFormat := eqb.chooseParameterFormatCode(m, oid, arg)
 		preferredErr := eqb.appendParam(m, oid, preferredFormat, arg)
 		if preferredErr == nil {
 			return nil
 		}
 
 		var otherFormat int16
 		if preferredFormat == TextFormatCode {
 			otherFormat = BinaryFormatCode
 		} else {
 			otherFormat = TextFormatCode
 		}
 
 		otherErr := eqb.appendParam(m, oid, otherFormat, arg)
 		if otherErr == nil {
 			return nil
 		}
 
 		return preferredErr // return the error from the preferred format
 	}
 
 	v, err := eqb.encodeExtendedParamValue(m, oid, format, arg)
 	if err != nil {
 		return err
 	}
 
 	eqb.ParamFormats = append(eqb.ParamFormats, format)
 	eqb.ParamValues = append(eqb.ParamValues, v)
 
 	return nil
 }
 
 // appendResultFormat appends a result format to the query.
 func (eqb *ExtendedQueryBuilder) appendResultFormat(format int16) {
 	eqb.ResultFormats = append(eqb.ResultFormats, format)
 }
 
 // reset readies eqb to build another query.
 func (eqb *ExtendedQueryBuilder) reset() {
 	eqb.ParamValues = eqb.ParamValues[0:0]
 	eqb.paramValueBytes = eqb.paramValueBytes[0:0]
 	eqb.ParamFormats = eqb.ParamFormats[0:0]
 	eqb.ResultFormats = eqb.ResultFormats[0:0]
 
 	if cap(eqb.ParamValues) > 64 {
 		eqb.ParamValues = make([][]byte, 0, 64)
 	}
 
 	if cap(eqb.paramValueBytes) > 256 {
 		eqb.paramValueBytes = make([]byte, 0, 256)
 	}
 
 	if cap(eqb.ParamFormats) > 64 {
 		eqb.ParamFormats = make([]int16, 0, 64)
 	}
 	if cap(eqb.ResultFormats) > 64 {
 		eqb.ResultFormats = make([]int16, 0, 64)
 	}
 }
 
 func (eqb *ExtendedQueryBuilder) encodeExtendedParamValue(m *pgtype.Map, oid uint32, formatCode int16, arg any) ([]byte, error) {
 	if anynil.Is(arg) {
 		return nil, nil
 	}
 
 	if eqb.paramValueBytes == nil {
 		eqb.paramValueBytes = make([]byte, 0, 128)
 	}
 
 	pos := len(eqb.paramValueBytes)
 
 	buf, err := m.Encode(oid, formatCode, arg, eqb.paramValueBytes)
 	if err != nil {
 		return nil, err
 	}
 	if buf == nil {
 		return nil, nil
 	}
 	eqb.paramValueBytes = buf
 	return eqb.paramValueBytes[pos:], nil
 }
 
 // chooseParameterFormatCode determines the correct format code for an
 // argument to a prepared statement. It defaults to TextFormatCode if no
 // determination can be made.
 func (eqb *ExtendedQueryBuilder) chooseParameterFormatCode(m *pgtype.Map, oid uint32, arg any) int16 {
 	switch arg.(type) {
 	case string, *string:
 		return TextFormatCode
 	}
 
 	return m.FormatCodeForOID(oid)
 }
 
 // appendParamsForQueryExecModeExec appends the args to eqb.
 //
 // Parameters must be encoded in the text format because of differences in type conversion between timestamps and
 // dates. In QueryExecModeExec we don't know what the actual PostgreSQL type is. To determine the type we use the
 // Go type to OID type mapping registered by RegisterDefaultPgType. However, the Go time.Time represents both
 // PostgreSQL timestamp[tz] and date. To use the binary format we would need to also specify what the PostgreSQL
 // type OID is. But that would mean telling PostgreSQL that we have sent a timestamp[tz] when what is needed is a date.
 // This means that the value is converted from text to timestamp[tz] to date. This means it does a time zone conversion
 // before converting it to date. This means that dates can be shifted by one day. In text format without that double
 // type conversion it takes the date directly and ignores time zone (i.e. it works).
 //
 // Given that the whole point of QueryExecModeExec is to operate without having to know the PostgreSQL types there is
 // no way to safely use binary or to specify the parameter OIDs.
 func (eqb *ExtendedQueryBuilder) appendParamsForQueryExecModeExec(m *pgtype.Map, args []any) error {
 	for _, arg := range args {
 		if arg == nil {
 			err := eqb.appendParam(m, 0, TextFormatCode, arg)
 			if err != nil {
 				return err
 			}
 		} else {
 			dt, ok := m.TypeForValue(arg)
 			if !ok {
 				var tv pgtype.TextValuer
 				if tv, ok = arg.(pgtype.TextValuer); ok {
 					t, err := tv.TextValue()
 					if err != nil {
 						return err
 					}
 
 					dt, ok = m.TypeForOID(pgtype.TextOID)
 					if ok {
 						arg = t
 					}
 				}
 			}
 			if !ok {
 				var dv driver.Valuer
 				if dv, ok = arg.(driver.Valuer); ok {
 					v, err := dv.Value()
 					if err != nil {
 						return err
 					}
 					dt, ok = m.TypeForValue(v)
 					if ok {
 						arg = v
 					}
 				}
 			}
 			if !ok {
 				var str fmt.Stringer
 				if str, ok = arg.(fmt.Stringer); ok {
 					dt, ok = m.TypeForOID(pgtype.TextOID)
 					if ok {
 						arg = str.String()
 					}
 				}
 			}
 			if !ok {
 				return &unknownArgumentTypeQueryExecModeExecError{arg: arg}
 			}
 			err := eqb.appendParam(m, dt.OID, TextFormatCode, arg)
 			if err != nil {
 				return err
 			}
 		}
 	}
 
 	return nil
 }