Use pgtype.Int2Array in pgx

conn.go

@@ -280,11 +280,12 @@ func (c *Conn) connect(config ConnConfig, network, address string, tlsConfig *tl
 	c.closedChan = make(chan error)
 
 	c.oidPgtypeValues = map[OID]pgtype.Value{
-		BoolOID: &pgtype.Bool{},
-		DateOID: &pgtype.Date{},
-		Int2OID: &pgtype.Int2{},
-		Int4OID: &pgtype.Int4{},
-		Int8OID: &pgtype.Int8{},
+		BoolOID:      &pgtype.Bool{},
+		DateOID:      &pgtype.Date{},
+		Int2OID:      &pgtype.Int2{},
+		Int2ArrayOID: &pgtype.Int2Array{},
+		Int4OID:      &pgtype.Int4{},
+		Int8OID:      &pgtype.Int8{},
 	}
 
 	if tlsConfig != nil {

pgtype/convert.go

@@ -93,3 +93,25 @@ func underlyingTimeType(val interface{}) (interface{}, bool) {
 
 	return time.Time{}, false
 }
+
+// underlyingSliceType gets the underlying slice type
+func underlyingSliceType(val interface{}) (interface{}, bool) {
+	refVal := reflect.ValueOf(val)
+
+	switch refVal.Kind() {
+	case reflect.Ptr:
+		if refVal.IsNil() {
+			return nil, false
+		}
+		convVal := refVal.Elem().Interface()
+		return convVal, true
+	case reflect.Slice:
+		baseSliceType := reflect.SliceOf(refVal.Type().Elem())
+		if refVal.Type().ConvertibleTo(baseSliceType) {
+			convVal := refVal.Convert(baseSliceType)
+			return convVal.Interface(), reflect.TypeOf(convVal.Interface()) != refVal.Type()
+		}
+	}
+
+	return nil, false
+}

pgtype/int2array.go

@@ -2,6 +2,7 @@ package pgtype
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 
 	"github.com/jackc/pgx/pgio"
@@ -14,6 +15,52 @@ type Int2Array struct {
 }
 
 func (a *Int2Array) ConvertFrom(src interface{}) error {
+	switch value := src.(type) {
+	case Int2Array:
+		*a = value
+	case []int16:
+		if value == nil {
+			*a = Int2Array{Status: Null}
+		} else if len(value) == 0 {
+			*a = Int2Array{Status: Present}
+		} else {
+			elements := make([]Int2, len(value))
+			for i := range value {
+				if err := elements[i].ConvertFrom(value[i]); err != nil {
+					return err
+				}
+			}
+			*a = Int2Array{
+				Elements:   elements,
+				Dimensions: []ArrayDimension{{Length: int32(len(elements)), LowerBound: 1}},
+				Status:     Present,
+			}
+		}
+	case []uint16:
+		if value == nil {
+			*a = Int2Array{Status: Null}
+		} else if len(value) == 0 {
+			*a = Int2Array{Status: Present}
+		} else {
+			elements := make([]Int2, len(value))
+			for i := range value {
+				if err := elements[i].ConvertFrom(value[i]); err != nil {
+					return err
+				}
+			}
+			*a = Int2Array{
+				Elements:   elements,
+				Dimensions: []ArrayDimension{{Length: int32(len(elements)), LowerBound: 1}},
+				Status:     Present,
+			}
+		}
+	default:
+		if originalSrc, ok := underlyingSliceType(src); ok {
+			return a.ConvertFrom(originalSrc)
+		}
+		return fmt.Errorf("cannot convert %v to Int2", value)
+	}
+
 	return nil
 }
 

values.go

@@ -1087,10 +1087,6 @@ func Encode(wbuf *WriteBuf, oid OID, arg interface{}) error {
 		// The name data type goes over the wire using the same format as string,
 		// so just cast to string and use encodeString
 		return encodeString(wbuf, oid, string(arg))
-	case []int16:
-		return encodeInt16Slice(wbuf, oid, arg)
-	case []uint16:
-		return encodeUInt16Slice(wbuf, oid, arg)
 	case []int32:
 		return encodeInt32Slice(wbuf, oid, arg)
 	case []uint32:
@@ -2410,42 +2406,45 @@ func encodeByteSliceSlice(w *WriteBuf, oid OID, value [][]byte) error {
 }
 
 func decodeInt2Array(vr *ValueReader) []int16 {
-	if vr.Len() == -1 {
-		return nil
-	}
-
 	if vr.Type().DataType != Int2ArrayOID {
 		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode oid %v into []int16", vr.Type().DataType)))
 		return nil
 	}
 
-	if vr.Type().FormatCode != BinaryFormatCode {
+	vr.err = errRewoundLen
+
+	var a pgtype.Int2Array
+	var err error
+	switch vr.Type().FormatCode {
+	case TextFormatCode:
+		err = a.DecodeText(&valueReader2{vr})
+	case BinaryFormatCode:
+		err = a.DecodeBinary(&valueReader2{vr})
+	default:
 		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
 		return nil
 	}
 
-	numElems, err := decode1dArrayHeader(vr)
 	if err != nil {
 		vr.Fatal(err)
 		return nil
 	}
 
-	a := make([]int16, int(numElems))
-	for i := 0; i < len(a); i++ {
-		elSize := vr.ReadInt32()
-		switch elSize {
-		case 2:
-			a[i] = vr.ReadInt16()
-		case -1:
+	if a.Status == pgtype.Null {
+		return nil
+	}
+
+	rawArray := make([]int16, len(a.Elements))
+	for i := range a.Elements {
+		if a.Elements[i].Status == pgtype.Present {
+			rawArray[i] = a.Elements[i].Int
+		} else {
 			vr.Fatal(ProtocolError("Cannot decode null element"))
 			return nil
-		default:
-			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an int2 element: %d", elSize)))
-			return nil
 		}
 	}
 
-	return a
+	return rawArray
 }
 
 func decodeInt2ArrayToUInt(vr *ValueReader) []uint16 {
@@ -2492,38 +2491,6 @@ func decodeInt2ArrayToUInt(vr *ValueReader) []uint16 {
 	return a
 }
 
-func encodeInt16Slice(w *WriteBuf, oid OID, slice []int16) error {
-	if oid != Int2ArrayOID {
-		return fmt.Errorf("cannot encode Go %s into oid %d", "[]int16", oid)
-	}
-
-	encodeArrayHeader(w, Int2OID, len(slice), 6)
-	for _, v := range slice {
-		w.WriteInt32(2)
-		w.WriteInt16(v)
-	}
-
-	return nil
-}
-
-func encodeUInt16Slice(w *WriteBuf, oid OID, slice []uint16) error {
-	if oid != Int2ArrayOID {
-		return fmt.Errorf("cannot encode Go %s into oid %d", "[]uint16", oid)
-	}
-
-	encodeArrayHeader(w, Int2OID, len(slice), 6)
-	for _, v := range slice {
-		if v <= math.MaxInt16 {
-			w.WriteInt32(2)
-			w.WriteInt16(int16(v))
-		} else {
-			return fmt.Errorf("%d is greater than max smallint %d", v, math.MaxInt16)
-		}
-	}
-
-	return nil
-}
-
 func decodeInt4Array(vr *ValueReader) []int32 {
 	if vr.Len() == -1 {
 		return nil