[JavaScript] Handling empty array

[khorolets]

Hi! Thank for your great work once again! I wonder if you can help me.

Description

I'm using generated javascript client in my project and I've met a bug, I suppose.

If my API returns an empty array client is returning it to me as a string and fails with message:

TypeError: data.map is not a function

It occurs in src/ApiClient.js:exports.convertToType()

} else if (Array.isArray(type)) {
          // for array type like: ['String']
          var itemType = type[0];

          return data.map(function(item) {
            return exports.convertToType(item, itemType);
          });
        } else if (typeof type === 'object') {

I suppose this data is handled somewhere in exports.prototype.deserialize

Because of

if (data == null || !Object.keys(data).length) {
      // SuperAgent does not always produce a body; use the unparsed response as a fallback
      data = response.text;
    }

Can you help me?

[wing328]

@khorolets is it correct to say that Object.keys(data).length) failed to return 0 somehow and that's why the following logic failed to work with empty array (which should have 0 size/length)?

https://github.com/swagger-api/swagger-codegen/blob/master/samples/client/petstore/javascript/src/ApiClient.js#L323-L326

[khorolets]

@wing328 yes. Do you need me to provide anything else to help you understand why this is happening?

[frol]

I am not sure what was the case for adding Object.keys(data).length check, but since

Object.keys([]).length == 0
Object.keys({}).length == 0
Object.keys('').length == 0
Object.keys(0).length == 0
Object.keys(1).length == 0
Object.keys(true).length == 0
Object.keys(false).length == 0

It should be addressed with a more specific check or even get fixed in the superuser library.

[wing328]

@khorolets I read this: http://stackoverflow.com/a/6700/677735, which suggests the approach is correct.

Are you using an old browser somehow?

[frol]

@wing328 Object.keys(data).length is fine by itself, but it catches too many cases as you can see in my previous comment, while I think, it should only catch {} (empty object) or '' (empty string).

P.S. We are using the latest browsers here Google Chrome (55+), Safari, and Firefox, but it is not the browser compatibility issue, anyway.

[frol]

This behavior was introduced in #4219.

@jordanyaker Could you please comment on this issue as it was your PR adding this !Object.keys(data).length check. Should be there added (typeof data === 'object' && typeof data.length === 'undefined' && !Object.keys(data).length) to ensure that we catch only empty objects?

[wing328]

@frol just saw your detailed comments and agree with a more specific check to handle the issue.