Get Map<String, dynamic> from Map<dynamic, dynamic> flutter - firebase

Question

I have the code below :
Map<dynamic, dynamic> result = snapshot.value;
Map<String, dynamic> data = Map<String, dynamic>();
for (dynamic type in result.keys) {
data[type.toString()] = result[type];
}
print(data);
print(data.runtimeType);
but data type is _InternalLinkedHashMap<String, dynamic> and i am not able to read its value, despite the ugly hack i have done above.
The direct cast also doesn't work : snapshot.value as Map<String, dynamic> throws the error : '_InternalLinkedHashMap<Object?, Object?>' is not a subtype of type 'Map<String, dynamic>'
I need to have a Map<String, dynamic> type to be able to create my custom class Object.
snapshot.value has a type of dynamic, but it's a json object that returns the result of a Realtime Database query and there is no documentation about how to retrieve the value into a Flutter object.
I have tried this answer but i can't use it as jsonDecode() takes a String as a parameter.

Answer 1

When I tried Tom's answer I got:
The argument type 'Object?' can't be assigned to the parameter type 'Map<dynamic, dynamic>'
To solve this, I had to do:
Map<String, dynamic>.from(snapshot.value as Map);
In fact, since all values in my database node are booleans, I was able to do this:
Map<String, bool>.from(snapshot.value as Map);

Answer 2

This recent Firecast video solved my problem at 27min.
I also had an non explicit Flutter error about another nested HashMap in my data model object that could not be converted directly.
The solution is to use Map<String, dynamic>.from(snapshot.value) and this for every nested Map you have in your data model object
EDIT : See Frank's answer below that is the correct one for the latest version of the firebase_database package.

Answer 3

I tested your code using DartPad:
void main() {
//Custom json
Map<dynamic, dynamic> json = {
"window": {
"title": "Sample Konfabulator Widget",
"name": "main_window",
"width": 500,
"height": 500
}
};
Map<dynamic, dynamic> result = json;
Map<String, dynamic> data = Map<String, dynamic>();
for (dynamic type in result.keys) {
data[type.toString()] = result[type];
}
print(data);
print(data['window']);
print(data['window']['title']);
}
Print 1:
{window: {title: Sample Konfabulator Widget, name: main_window, width: 500, height: 500}}
Print 2:
{title: Sample Konfabulator Widget, name: main_window, width: 500, height: 500}
Print 3:
Sample Konfabulator Widget
I don't understand the problem

Answer 4

This will recursively convert a Map<dynamic, dynamic> to Map<String, dynamic>:
Map<String, dynamic> dynamicMapToString(Map<dynamic, dynamic> data) {
List<dynamic> _convertList(List<dynamic> src) {
List<dynamic> dst = [];
for (int i = 0; i < src.length; ++i) {
if (src[i] is Map<dynamic, dynamic>) {
dst.add(dynamicMapToString(src[i]));
} else if (src[i] is List<dynamic>) {
dst.add(_convertList(src[i]));
} else {
dst.add(src[i]);
}
}
return dst;
}
Map<String, dynamic> retval = {};
for (dynamic key in data.keys) {
if (data[key] is Map<dynamic, dynamic>) {
retval[key.toString()] = dynamicMapToString(data[key]);
} else if (data[key] is List<dynamic>) {
retval[key.toString()] = _convertList(data[key]);
} else {
retval[key.toString()] = data[key];
}
}
return retval;
}