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Date is not validated correctly as type: string, format: date-time

See original GitHub issue


I want to return the created and lastModified timestamp from the database which I define in my ORM with type Date.

If I print the response object in my express router before returning it, it looks like this:

User {
   id: '1fe87c1d-5d31-4426-8757-aa5e62d2344e',
   lastModified: 2020-02-21T09:26:43.603Z,
   created: 2020-02-21T09:25:48.151Z,

If I call the endpoint I get the following reponse object:

  "data": [
      "id": "1fe87c1d-5d31-4426-8757-aa5e62d2344e",
      "lastModified": "2020-02-21T09:26:43.603Z",
      "created": "2020-02-21T09:25:48.151Z"

-> correctly stringified

As soon as I set the validateResponses option in the OpenApiValidator on true, I get the following error message:

  "error": "[0].lastModified should be string,[0].created should be string,

… although it is a string in the upper example

Issue Analytics

  • State:closed
  • Created 4 years ago
  • Reactions:4
  • Comments:7 (2 by maintainers)

github_iconTop GitHub Comments

martinbarkcommented, Feb 25, 2020

I just hit this same issue today. It’s because the date is an object not a string. At the point the response it validated it’s still a Date object. When you print it date.toJSON() is called to convert it to a string. It’s not specific to Date, you would see this issue on any object that has a toJSON() function

The only reliable way i found to work around this is to JSON.stringify() then JSON.parse() the response body before it’s validated. This means the response body is now formatted as the destination will see the message before it’s validated.

I added this code after OpenApiValidator was been installed as a workaround

app.use((req, res, next) => {
  const original = res.json;
  res.json = function jsonp(json) {
    return, JSON.parse(JSON.stringify(json)));
severinwullschlegercommented, Feb 25, 2020

Thanks a lot. The workaround worked for me too.

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