add new elements to class - flutter

Question

I've written a class like this,
class LessonCategory{final String name;
LessonCategory(this.name);
#override
String toString() {
return 'LessonCategory{name: $name}';
}
}
class Lessons {
final String lessonsName;
int discontinuity;
final LessonCategory lesscategory;
Lessons(this.lessonsName, this.discontinuity,
this.lesscategory,
);
#override
String toString() {
return 'Lessons{lessonsName: $lessonsName, discontinuity:
$discontinuity, lesscategory: $lesscategory}';
}
}
class Data {
static List<LessonCategory> categories = [
LessonCategory("a1"),
];
static List<Lessons> lessons = [
Lessons(
'Lesson A1',
0,
getCategoryFromName("a1"),
),
];
static LessonCategory getCategoryFromName(name) {
return categories.firstWhere(
(c) => c.name.toLowerCase() == name.toString().toLowerCase());
}
}
But I can't figure out how to add a new element.I already tried add,push,insert (or i missed something).
Can someone please show me the right way?
i want something like
Data.lessons.add({
lessonsName: 'Lesson Z1',
discontinuity: 0
lessCategory: 'a1'
});

Answer 1

just remove static syntax. if it is defined as static, it will be immutable
class Data {
static List<LessonCategory> categories = [
LessonCategory("a1"),
];
List<Lessons> lessons = [ // Remove Static syntax
Lessons(
'Lesson A1',
0,
getCategoryFromName("a1"),
),
];
static LessonCategory getCategoryFromName(name) {
return categories.firstWhere(
(c) => c.name.toLowerCase() == name.toString().toLowerCase());
}
}
but also we can correct another syntaxes
Data newData = Data();
newData.lessons.add(Lessons(
'Lesson Z1', // remove named parameters, and use positional params
0,
LessonCategory('a1'),
));
print("New Length : ${newData.lessons.length}");
Fully working code
class LessonCategory {
final String name;
LessonCategory(this.name);
#override
String toString() {
return 'LessonCategory{name: $name}';
}
}
class Lessons {
final String lessonsName;
int discontinuity;
final LessonCategory lesscategory;
Lessons(
this.lessonsName,
this.discontinuity,
this.lesscategory,
);
#override
String toString() {
return """Lessons{lessonsName: $lessonsName, discontinuity: $discontinuity, lesscategory: $lesscategory}""";
}
}
class Data {
static List<LessonCategory> categories = [
LessonCategory("a1"),
];
List<Lessons> lessons = [ // Remove Static syntax
Lessons(
'Lesson A1',
0,
getCategoryFromName("a1"),
),
];
static LessonCategory getCategoryFromName(name) {
return categories.firstWhere(
(c) => c.name.toLowerCase() == name.toString().toLowerCase());
}
#override
String toString() {
return "{${lessons.map((fruit) => print(fruit))}}";
}
}
main(List<String> args) {
Data newData = Data(); // Create instance first
newData.lessons.add(Lessons(
'Lesson Z1', // remove named parameters, and use positional params
0,
LessonCategory('a1'),
));
print("New Length : ${newData.lessons.length}");
newData.lessons.add(Lessons(
'Lesson Z1',
0,
LessonCategory('a1'),
));
print("New Length : ${newData.lessons.length}");
print("${newData.lessons}");
}
which we able to play arount in Dartpad
Result

Answer 2

remove the static syntax and the problem will be solved