Flutter access model attribute using dynamic key [duplicate] - object

Question

I'm trying to access a class value by using a variable previously defined in dart, but I keep getting the error the operator [] isn't defined for the class
In Javascript I would access an object value using a variable like this:
let movie = {
movieTitle : 'Toy Story',
actor: 'Tom Hanks'
}
let actorName = 'actor';
console.log(movie[actorName]); // <- what I'm trying to replicate in dart
// expected output: Tom Hanks
Here is what I've tried and is throwing that error
class Movie {
String name;
String actor;
String producer;
}
void main() {
var movieTitle = new Movie();
movieTitle.name = 'Toy Story';
movieTitle.actor = 'Tom Hanks';
print(movieTitle.actor); <- prints out Tom Hanks as expected
var actorName = 'actor';
print(movieTitle[actorName]); <- throws error
}
I expect to be able to use a variable on the fly to access the value.
A trivial use case for me would be if I had a a list of Movie classes, where some actors and producers are null, I would like to filter on either non null actors or producer with a function like so:
List values = movieList.where((i) => i.actor != "null").toList(); // returns all Movies in movieList where the actor value isn't the string "null"
var actorIsNull = 'actor';
List values = movieList.where((i) => i[actorisNull] != "null").toList(); // throws error

Answer 1

You can createn a toMap() function in your Movie class and access properties using [] operator
class Movie {
String name;
String actor;
String producer;
Map<String, dynamic> toMap() {
return {
'name': name,
'actor' : actor,
'producer' : producer,
};
}
}
Now Movie class properties can be accessed as:
Movie movie = Movie();
movie.toMap()['name'];

Answer 2

You cannot access class members by a string containing their name. (Except with mirrors - outside the scope of this answer.)
You could remove the class altogether and just use a Map<String, String>.
Map<String, String> movie = {
'movieTitle': 'Toy Story',
'actor': 'Tom Hanks',
}
You could add some bool methods on the class.
bool hasNoActor() => actor == null;
...
List values = movieList.where((m) => !m.hasNoActor()).toList();
Or, you could pass a lambda to your mapper.
Movie movieTitle = Movie()
..name = 'Toy Story'
..actor = 'Tom Hanks';
Function hasActor = (Movie m) => m.actor != null;
List values = movieList.where(hasActor).toList();