Add Query.Consistency() and .MapScanCAS()

query.go

@@ -33,6 +33,16 @@ type Query interface {
 	// were selected, ErrNotFound is returned.
 	MapScan(m map[string]interface{}) error
 
+	// MapScanCAS executes a lightweight transaction (i.e. an UPDATE or INSERT
+	// statement containing an IF clause). If the transaction fails because
+	// the existing values did not match, the previous values will be stored
+	// in dest map.
+	//
+	// As for INSERT .. IF NOT EXISTS, previous values will be returned as if
+	// SELECT * FROM. So using ScanCAS with INSERT is inherently prone to
+	// column mismatching. MapScanCAS is added to capture them safely.
+	MapScanCAS(dest map[string]interface{}) (applied bool, err error)
+
 	// Scan executes the query, copies the columns of the first selected row
 	// into the values pointed at by dest and discards the rest. If no rows
 	// were selected, ErrNotFound is returned.
@@ -48,6 +58,11 @@ type Query interface {
 
 	// SetConsistency sets the consistency level for this query.
 	SetConsistency(c gocql.Consistency)
+
+	// Consistency sets the consistency level for this query. If no consistency
+	// level have been set, the default consistency level of the cluster
+	// is used.
+	Consistency(c gocql.Consistency) Query
 }
 
 var (
@@ -90,6 +105,12 @@ func (m QueryMock) MapScan(mm map[string]interface{}) error {
 	return m.Called(mm).Error(0)
 }
 
+// MapScan implements Query.
+func (m QueryMock) MapScanCAS(mm map[string]interface{}) (bool, error) {
+	call := m.Called(mm)
+	return call.Bool(0), call.Error(1)
+}
+
 // Scan implements Query.
 func (m QueryMock) Scan(dest ...interface{}) error {
 	return m.Called(dest).Error(0)
@@ -108,6 +129,10 @@ func (m QueryMock) SetConsistency(c gocql.Consistency) {
 	m.Called(c)
 }
 
+func (m QueryMock) Consistency(c gocql.Consistency) Query {
+	return m.Called(c).Get(0).(Query)
+}
+
 type query struct {
 	q *gocql.Query
 }
@@ -151,3 +176,11 @@ func (q query) GetConsistency() gocql.Consistency {
 func (q query) SetConsistency(c gocql.Consistency) {
 	q.q.SetConsistency(c)
 }
+
+func (q query) Consistency(c gocql.Consistency) Query {
+	return &query{q: q.q.Consistency(c)}
+}
+
+func (q query) MapScanCAS(dest map[string]interface{}) (applied bool, err error) {
+	return q.q.MapScanCAS(dest)
+}

query_test.go

@@ -3,9 +3,10 @@ package gockle
 import (
 	"context"
 	"fmt"
-	"github.com/gocql/gocql"
 	"reflect"
 	"testing"
+
+	"github.com/gocql/gocql"
 )
 
 func TestQuery(t *testing.T) {
@@ -73,9 +74,11 @@ func TestQueryMock(t *testing.T) {
 		{"Iter", nil, []interface{}{it}},
 		{"MapScan", []interface{}{map[string]interface{}(nil)}, []interface{}{nil}},
 		{"MapScan", []interface{}{map[string]interface{}{"a": 1}}, []interface{}{e}},
+		{"MapScanCAS", []interface{}{map[string]interface{}{"a": 1}}, []interface{}{true, e}},
 		{"Release", nil, nil},
 		{"GetConsistency", nil, []interface{}{gocql.Quorum}},
 		{"SetConsistency", []interface{}{gocql.One}, nil},
+		{"Consistency", []interface{}{gocql.One}, []interface{}{m}},
 	})
 }