camli/db: typecheck & convert pre-bound statement parameters

Change-Id: Ic9b6dfa7b1fef0c6046c2e0454e996e2d5a8dfa6

lib/go/camli/db/db_test.go

@@ -45,6 +45,19 @@ func TestQuery(t *testing.T) {
 
 }
 
+// just a test of fakedb itself
+func TestBogusPreboundParameters(t *testing.T) {
+	db := newTestDB(t, "foo")
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	_, err := db.Prepare("INSERT|t1|name=?,age=bogusconversion")
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+	if err.String() != `fakedb: invalid conversion to int32 from "bogusconversion"` {
+		t.Errorf("unexpected error: %v", err)
+	}
+}
+
 func TestDb(t *testing.T) {
 	db := newTestDB(t, "foo")
 	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")

lib/go/camli/db/fakedb_test.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"strconv"
 	"strings"
 	"sync"
 
@@ -94,7 +95,7 @@ type fakeStmt struct {
 
 	colName      []string // used by CREATE, INSERT
 	colType      []string // used by CREATE
-	colValue     []string // used by INSERT (mix of strings and "?" for bound params)
+	colValue     []interface{} // used by INSERT (mix of strings and "?" for bound params)
 	placeholders int      // number of ? params
 
 	placeholderConverter []dbimpl.ValueConverter // used by INSERT
@@ -240,16 +241,27 @@ func (c *fakeConn) Prepare(query string) (dbimpl.Stmt, os.Error) {
 			if !ok {
 				return nil, errf("INSERT table %q references non-existent column %q", stmt.table, column)
 			}
+			var subsetVal interface{}
 			if value != "?" {
-				// TODO(bradfitz): check that
-				// pre-bound value type conversion is
-				// valid for this column type
+				// Convert to dbimpl subset type
+				switch ctype {
+				case "string":
+					subsetVal = []byte(value)
+				case "int32":
+					i, err := strconv.Atoi(value)
+					if err != nil {
+						return nil, errf("invalid conversion to int32 from %q", value)
+					}
+					subsetVal = int64(i) // int64 is a subset type, but not int32
+				default:
+					return nil, errf("unsupported conversion for pre-bound parameter %q to type %q", value, ctype)
+				}
 			} else {
 				stmt.placeholders++
 				stmt.placeholderConverter = append(stmt.placeholderConverter, converterForType(ctype))
 			}
 			stmt.colName = append(stmt.colName, column)
-			stmt.colValue = append(stmt.colValue, value)
+			stmt.colValue = append(stmt.colValue, subsetVal)
 		}
 	default:
 		return nil, errf("unsupported command type %q", cmd)
@@ -306,7 +318,7 @@ func (s *fakeStmt) execInsert(args []interface{}) (dbimpl.Result, os.Error) {
 			return nil, fmt.Errorf("fakedb: column %q doesn't exist or dropped since prepared statement was created", colname)
 		}
 		var val interface{}
-		if s.colValue[n] == "?" {
+		if strvalue, ok := s.colValue[n].(string); ok && strvalue == "?" {
 			val = args[argPos]
 			argPos++
 		} else {