Add WhereMultiple

- Change the order of the args in WhereClause to support varargs

strmangle/strmangle.go

@@ -245,7 +245,7 @@ func GenerateParamFlags(colCount int, startAt int, groupAt int) string {
 
 // WhereClause returns the where clause using start as the $ flag index
 // For example, if start was 2 output would be: "colthing=$2 AND colstuff=$3"
-func WhereClause(cols []string, start int) string {
+func WhereClause(start int, cols ...string) string {
 	if start == 0 {
 		panic("0 is not a valid start number for whereClause")
 	}
@@ -258,6 +258,32 @@ func WhereClause(cols []string, start int) string {
 	return strings.Join(ret, " AND ")
 }
 
+// WhereMultiple is a version of Where that binds multiple checks together
+// with an or statement.
+// WhereMultiple(1, 2, "a", "b") = "(a=$1 and b=$2) or (a=$3 and b=$4)"
+func WhereMultiple(start, count int, cols ...string) string {
+	if start == 0 {
+		panic("0 is not a valid start number for whereMultiple")
+	}
+
+	buf := &bytes.Buffer{}
+	for i := 0; i < count; i++ {
+		if i != 0 {
+			buf.WriteString(" OR ")
+		}
+		buf.WriteByte('(')
+		for j, key := range cols {
+			if j != 0 {
+				buf.WriteString(" AND ")
+			}
+			fmt.Fprintf(buf, `"%s"=$%d`, key, start+i*len(cols)+j)
+		}
+		buf.WriteByte(')')
+	}
+
+	return buf.String()
+}
+
 // InClause generates SQL that could go inside an "IN ()" statement
 // $1, $2, $3
 func InClause(start, count int) string {

strmangle/strmangle_test.go

@@ -315,14 +315,14 @@ func TestWhereClause(t *testing.T) {
 	}
 
 	for i, test := range tests {
-		r := WhereClause(test.Cols, test.Start)
+		r := WhereClause(test.Start, test.Cols...)
 		if r != test.Should {
 			t.Errorf("(%d) want: %s, got: %s\nTest: %#v", i, test.Should, r, test)
 		}
 	}
 }
 
-func TestWherePrimaryKeyPanic(t *testing.T) {
+func TestWhereClausePanic(t *testing.T) {
 	t.Parallel()
 
 	defer func() {
@@ -331,7 +331,41 @@ func TestWherePrimaryKeyPanic(t *testing.T) {
 		}
 	}()
 
-	WhereClause(nil, 0)
+	WhereClause(0)
+}
+
+func TestWhereMultiple(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		Cols   []string
+		Start  int
+		Count  int
+		Should string
+	}{
+		{Cols: []string{"col1", "col2"}, Start: 2, Count: 2, Should: `("col1"=$2 AND "col2"=$3) OR ("col1"=$4 AND "col2"=$5)`},
+		{Cols: []string{"col1", "col2"}, Start: 4, Count: 2, Should: `("col1"=$4 AND "col2"=$5) OR ("col1"=$6 AND "col2"=$7)`},
+		{Cols: []string{"col1", "col2", "col3"}, Start: 4, Count: 1, Should: `("col1"=$4 AND "col2"=$5 AND "col3"=$6)`},
+	}
+
+	for i, test := range tests {
+		r := WhereMultiple(test.Start, test.Count, test.Cols...)
+		if r != test.Should {
+			t.Errorf("(%d) want: %s, got: %s", i, test.Should, r)
+		}
+	}
+}
+
+func TestWhereMultiplePanic(t *testing.T) {
+	t.Parallel()
+
+	defer func() {
+		if recover() == nil {
+			t.Error("did not panic")
+		}
+	}()
+
+	WhereMultiple(0, 0)
 }
 
 func TestInClause(t *testing.T) {