[BUG] Properties marked nullable in swagger file are not nullable in generated output

[point-source]

Describe the bug
I have a property on line 18748 of this swagger file like so:

"limit": {
    "type": "number",
    "format": "double",
    "description": "For `credit`-type accounts, this represents the credit limit.\n\nFor `depository`-type accounts, this represents the pre-arranged overdraft limit, which is common for current (checking) accounts in Europe.\n\nIn North America, this field is typically only available for `credit`-type accounts.",
    "nullable": true
},

The generated output for this property is:

limit: (json['limit'] as num).toDouble(),

For reference, this is part of the AccountBalance model:

AccountBalance _$AccountBalanceFromJson(Map<String, dynamic> json) =>
    AccountBalance(
      available: (json['available'] as num).toDouble(),
      current: (json['current'] as num).toDouble(),
      limit: (json['limit'] as num).toDouble(),
      isoCurrencyCode: json['iso_currency_code'] as String,
      unofficialCurrencyCode: json['unofficial_currency_code'] as String,
      lastUpdatedDatetime: json['last_updated_datetime'] == null
          ? null
          : DateTime.parse(json['last_updated_datetime'] as String),
    );

When I try to deserialize the server response, it fails because Null is not a subtype of num.

Expected behavior
The generated output should allow the limit property (and other properties marked null) to be null.

Swagger specification link
Link to swagger/OpenApi documentation

Library version used:
master branch on commit b9ecb61 (v2.8.7)

Additional Info:
I suspect the issue might be on this line:
..isNullable = (json[kIsNullable] ?? json[kIsNullable] ?? false) as bool;

It appears to me like the intention was to handle both "x-nullable" and "nullable" cases but accidentally is checking "x-nullable" twice.

Patching this results in this output:

AccountBalance _$AccountBalanceFromJson(Map<String, dynamic> json) =>
    AccountBalance(
      available: (json['available'] as num?)?.toDouble(),
      current: (json['current'] as num?)?.toDouble(),
      limit: (json['limit'] as num?)?.toDouble(),
      isoCurrencyCode: json['iso_currency_code'] as String?,
      unofficialCurrencyCode: json['unofficial_currency_code'] as String?,
      lastUpdatedDatetime: json['last_updated_datetime'] == null
          ? null
          : DateTime.parse(json['last_updated_datetime'] as String),
    );

While this fixes the case that started this ticket, it did not fix a similar issue with the component on line 18570 as references from line 43202:

            "PlaidError": {
                "description": "We use standard HTTP response codes for success and failure notifications, and our errors are further classified by `error_type`. In general, 200 HTTP codes correspond to success, 40X codes are for developer- or user-related failures, and 50X codes are for Plaid-related issues. An Item with a non-`null` error object will only be part of an API response when calling `/item/get` to view Item status. Otherwise, error fields will be `null` if no error has occurred; if an error has occurred, an error code will be returned instead.",
                "type": "object",
                "additionalProperties": true,
                "title": "Error",
                "nullable": true,
                "properties": {
                    "error_type": {
                        "$ref": "#/components/schemas/PlaidErrorType"
                    },
...

Reference to the component:

                    "error": {
                        "$ref": "#/components/schemas/PlaidError"
                    },

[aledavidgueva]

Hi! I have the same problem starting from version 2.8.4... By the moment, i rollback to version 2.8.3

[Vovanella95]

@point-source Could you please share swagger of AccountBalance?

[Vovanella95]

@aledavidgueva could you please share Your swagger file?

[point-source]

@Vovanella95 I did. It's right there where it says "Link to Swagger/OpenApi documentation".

But here's another link just in case: https://raw.githubusercontent.com/plaid/plaid-openapi/master/2020-09-14.yml

I just converted it to json with a yaml to json converter online.

[Vovanella95]

@point-source cool, will take a look!

[point-source]

I fixed the first part of this bug here: point-source@cee0a10

As best I can tell, the second example in my post is failing because referenced models which have a nullable flag are not marked nullable. Line 684 of swagger_models_generator.dart should be handling this but the prop.isNullable flag is not properly set at the time that line is executed.

[fryette]

@point-source will you be able to provide a pull request with a fix?

[point-source]

Sadly not. I was only able to fix the first issue but not the second. I don't understand this library well enough to close the entire ticket. I can still open a PR though if you want to pull in the bit that I did do. Perhaps with some guidance on where to look I can help with the rest?

[point-source]

Is there any other way I can help with this?

[Vovanella95]

@point-source sorry no updates for now. Will take a look into it this week. Thanks for patience!