Flitering list that may content null or empty string-CodePudding

I am filtering a list as follows:

return Container(
                      child: FutureBuilder(
                        future: fetchCremas(),
                        builder: (context, snapshot) {
                          if (snapshot.hasData) {
                            var filteredList = snapshot.data;
                            filteredList = filteredList
                                .where((element) => (element.nombre
                                .toLowerCase()
                                .contains(
                                _controller.text.toLowerCase())
                                || element.descripcion.toLowerCase().contains(
                                    _controller.text.toLowerCase())
                                || element.sub_cat_nombre.toLowerCase().contains(
                                    _controller.text.toLowerCase())
                                || element.sub_cat2_nombre.toLowerCase().contains(
                                    _controller.text.toLowerCase())
                                || element.sub_cat3_nombre.toLowerCase().contains(
                                    _controller.text.toLowerCase())
                            ))
                                .toList();

The issue is that element.sub_cat3_nombre may be empty or null.

Using this code I am getting an error

The method 'toLowerCase' was called on null.
Receiver: null
Tried calling: toLowerCase()

How can I keep filtering on element.sub_cat3_nombre taking into account that it may be empty or null?

CodePudding user response：

some value is Nullable String not String

handled it from backend return String without Nullable , to avoid extra cast or check-null

CodePudding user response：

This should work:

element.sub_cat3_nombre?.toLowerCase()

CodePudding user response：

Could you try this?

filteredList.where((element) => (element.nombre?.toLowerCase() ?? here put replacement object

or you could use if(element.nombre != null) before you start filtering