package handler import ( "io" "net/http" "reflect" "github.com/nesterow/dal/pkg/adapter" "github.com/nesterow/dal/pkg/proto" ) /* QueryHandler is a http.Handler that reads a proto.Request from the request body, parses it into a query, executes the query on the provided db and writes the result to the response body. - The request body is expected to be in msgpack format (proto.Request). - The response body is written in msgpack format. - The respose is a stream of rows (proto.Row), where the first row is the column names. - The columns are sorted alphabetically, so it is client's responsibility to match them and sort as needed. */ func QueryHandler(db adapter.DBAdapter) http.Handler { dialect := adapter.GetDialect(db.Type) return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { body, err := io.ReadAll(r.Body) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } req := proto.Request{} req.UnmarshalMsg(body) query, err := req.Parse(dialect) if err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return } if query.Exec { result, err := db.Exec(query) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } w.Header().Set("Content-Type", "application/x-msgpack") ra, _ := result.RowsAffected() la, _ := result.LastInsertId() res := proto.Response{ Id: 0, RowsAffected: ra, LastInsertId: la, } out, _ := res.MarshalMsg(nil) w.Write(out) return } rows, err := db.Query(query) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } defer rows.Close() w.Header().Set("X-Content-Type-Options", "nosniff") w.Header().Set("Content-Type", "application/x-msgpack") flusher, ok := w.(http.Flusher) if !ok { http.Error(w, "expected http.ResponseWriter to be an http.Flusher", http.StatusInternalServerError) return } columns, _ := rows.Columns() types, _ := rows.ColumnTypes() cols, _ := proto.MarshalRow(columns) w.Write(cols) flusher.Flush() for rows.Next() { data := make([]interface{}, len(columns)) for i := range data { typ := reflect.New(types[i].ScanType()).Interface() data[i] = &typ } rows.Scan(data...) cols, _ := proto.MarshalRow(data) w.Write(cols) flusher.Flush() } }) }