The element type 'int' can't be assigned to the map value type 'FieldValue' when trying to assign a new value - Flutter

MrTacio
November 18, 2022
177 views
0 votes
2 Answers

I have initial data which works fine.

var data = {field1: FieldValue.increment(1)};

And it is also fine when I add another field to the data.

data.addAll({field2: FieldValue.increment(1)});

But if I set the value to 0, it won’t allow me to.

data.addAll({field3: 0});

It will give an error of:
The element type ‘int’ can’t be assigned to the map value type ‘FieldValue’.

I tried doing this but still, have the same issue.

data[field3] = 0;

How will I set the field3 to a specific value?

Note:
This is the full code.

DocumentReference<Map<String, dynamic>> ref = db.collection('MyCollect').doc(uid);
var data = {field1: FieldValue.increment(1)};
data.addAll({field2: FieldValue.increment(1)});
data.addAll({field3: 0});
ref.set(data, SetOptions(merge: true));

Answers

- rodpold
- November 21, 2022 at 2:16 am
- 0 votes
0
check your dart type.

Difference between "var" and "dynamic" type in Dart?

the type var can’t change type of variable. so check your code.
```
var data = {field1: FieldValue.increment(1)};
```
maybe data’s type fixed something <String, FieldValue>

you can try dynamic type.
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- Gwhyyy
- November 21, 2022 at 2:43 am
- 0 votes
0
For a better understanding

you can use the var keyword when you don’t want to explicitly give a type but its value decides its type, and for the next operations/assignments, it will only accept that specific type that it took from the first time.

On the other hand, the dynamic keyword is used also to not explicitly set a type for a variable, but every other type is valid for it.
```
var a = "text";
a = "text2"; // ok
a = 1; // throws the error

dynamic b = "text";
b = "text2"; // ok
b = 1; // also ok
```
in your case, you’re using the var keyword, so in the first value assignment it takes its type:
```
var data = {field1: FieldValue.increment(1)}; // takes the Map<String, FieldValue> type
data.addAll({field3: 0}); // 0 is int and FieldValue.increment(1) is FieldValue type,  so it throws an error
```
However, you can fix the problem and let your data variable accept any kind of element types by either using the dynamic keyword:
```
dynamic data = {field1: FieldValue.increment(1)}; // will accept it.
```
or, specifying that this is a Map, but the values of it are dynamic:
```
Map<String, dynamic> data = {field1: FieldValue.increment(1)}; // will accept it also.
```
Hope this helps!
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