[TypeScript][Fetch] only call toISOString() if date object

[tsiq-jeremy]

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Description of the PR

@mhardorf @leonyu @roni-frantchi @bherila

Related to this issue. When using TypeScript Fetch and passing parameters to a "Date" field, they expect a type of "string", but then toISOString() is called on it, which causes the function to fail. Same issue on swagger-codegen.

Example json swagger:

        "parameters": [
          {
            "name": "date",
            "in": "query",
            "type": "string",
            "format": "date"
          }
        ]

in In `AbstractTypeScriptClientCodegen.java the Typings map:

typeMapping.put("date", "string");
typeMapping.put("DateTime", "Date");

template issue:

{{#isDate}}
queryParameters['{{baseName}}'] = (requestParameters.{{paramName}} as any).toISOString();
{{/isDate}}

requestParameters.{{paramName}} can never be a Date, since it has to be a string.

[tsiq-jeremy]

Is there a technical committee to review this?

[fabricio-godoi]

Is there any chance that this PR would be merged any time soon? I would contribute myself if I had not seen this PR, but since it is already created I would like to see this feature in production.

I'm still getting this error from the editor.swagger.io client generator.

[fabricio-godoi]

Just a notice, if the param type is "datetime" the string length should surpass 10 characters since it contains the timestamp as well.
For instance: "2014-01-01T23:28:56.782Z" or even "2014-02-01T09:28:56.321-10:00"

I suggest checking the type for date if you want to keep the substr(0,10) or else this would be problematic for datetime types.

[HugoMario]

hey guys, thanks for PR, please ping me once this is ready to be merged