Flutter build ListView with RegExpr condition-CodePudding

I have the following list coming from firebase:

[widget.recipeDocument['ingredients'] = 2 eggs, 2 tbsp milk, 30 g flour, 2 tbsp sugar, vanillaextract]

For my list view I split the strings into two parts. Part one is the ingredient amount, with which I do a calculation based on the user's input for the serving size. Part two is the ingredient name. It works for ingredients where I have an amount and an ingredient name. But as you see in my list, I also have "vanillaextract" without an amount. My list view breaks at this point. I am thinking of using RegExpr to detect the ingredient without a space, but I don't know how.

 child: ListView.builder(
                                scrollDirection: Axis.vertical,
                                shrinkWrap: true,
                                primary: false,
                               
                                          itemCount:widget.recipeDocument['ingredients'].length,
                                          itemBuilder: (context, index) {
                                            final ingredient = widget.recipeDocument['ingredients'][index];
                                            RegExp regExp = RegExp(" ");
                                            print('REG EXPR = ${regExp.allMatches(ingredient).length}');
                                            int splitt = ingredient.indexOf(" ");
                                            String measure = ingredient.substring(0,splitt).trim();
                                            String ingredient_name =  ingredient.substring(ingredient.indexOf(" ")   1);
                                            double x = double.parse(measure);
                                            double calc = x * _counter;
                                           return Card(
                                             color: Colors.transparent,
                                             shape: RoundedRectangleBorder(
                                             borderRadius: BorderRadius.circular(25),
                                              ),
                                            child:
                                           ListTile(
                                            dense: true,
                                            visualDensity: VisualDensity(vertical: -3), // to compact
                                            contentPadding: EdgeInsets.only(left: 15.0, right: 15.0),
                                            tileColor: Colors.grey.withOpacity(0.2),
                                            shape: RoundedRectangleBorder(
                                            borderRadius: BorderRadius.only(
                                            topLeft: Radius.circular(25),
                                            topRight: Radius.circular(25),
                                            bottomRight: Radius.circular(25),
                                            bottomLeft: Radius.circular(25))),
                                            title: 
                                             Text('${(prettify(calc))} ${ingredient_name}',
                                             style: GoogleFonts.nunito(color: Colors.white, fontSize: 18))
                                           )
                                           );
                                          }
                                          
                              ),

CodePudding user response：

I would make it like this:

final split = ingredient.split(' ');
double calc = (double.tryParse(split[0]) ?? 0) * _counter;
String ingredient_name = calc == 0 ? ingredient : split.skip(1).join(' ');

Then let the text be

Text('${calc == 0 ? '' : '${prettify(calc)} '}$ingredient_name',

CodePudding user response：

You could use the hasMatch function regExp class to know if the string is matchin your regex :

var list = ["with space", "withoutspace"];
  for(var elm in list)
  {
    var regEx = RegExp(r'\s');
    var match = regEx.hasMatch(elm);
    print("$elm, has space: $match");
  }

result :

with space, has space: true
withoutspace, has space: false

I sugest using "\s" instead of " " as it detect all form of spacing, just to be safe !