Typescript 带离子束的可调物体

您好，下面的typscript代码对后端进行rest调用，该后端在typscript中返回一个包含以下数据的对象数组，并在执行代码时通过生成映射来过滤数据。我有以下错误：

错误：

item.variants is not iterable

urlTocall = 'http://link';
            const headers = new Headers();
            console.log('Params: ' + params);
            headers.append('Authorization', 'Basic' + btoa(username + ':' + password));
            return this.http.get(urlTocall, params, headers).pipe(map((res: any) => {
                console.log('rest.data: ' + res.data);
               
                return res.data.map((item) => {
                console.log('item: ' + item.attributes);
                return this.mappingService.toProduct(item.attributes, this.authService.imagesBaseUrl);
            });

类型脚本代码：

item.variants is not iterable

urlTocall = 'http://link';
            const headers = new Headers();
            console.log('Params: ' + params);
            headers.append('Authorization', 'Basic' + btoa(username + ':' + password));
            return this.http.get(urlTocall, params, headers).pipe(map((res: any) => {
                console.log('rest.data: ' + res.data);
               
                return res.data.map((item) => {
                console.log('item: ' + item.attributes);
                return this.mappingService.toProduct(item.attributes, this.authService.imagesBaseUrl);
            });