Exclude records where field is present (ie., return only open questions)

Question

How do I exclude records based on the presence of a certain field (like the equivalent of SQL's [fieldname] Is Null)?

Example:

• Results for Closed questions include field closed_date=1234567890.

• Results for Open questions do not include this field as a Null as I would expect.

Is there a parameter I can add to the URL to exclude questions that have the field?

---

The only information I could find was from the documentation:

Absent Fields

_{To save space, the API does not return null values, instead opting to exclude the field altogether in the returned JSON. Fields that are not always guaranteed to be set (closed_date on question objects for example) are indicated in the per-type documentation. (Source)}

Answer 1

You have 2 questions:

1. "How do I exclude records based on the presence of a certain field?"
   Answer: The API will not do this for you; your code must filter out these results.
   
   

2. "(How do I ) return only open questions?"
   Answer: Use the /search/advanced route.

---

Exclude records where field is present:

The API does not do this for any field, and seems unlikely to add the capability. ^{_{(See this somewhat related answer to "API responses are sometimes missing fields".}}}

Your app/script must loop through the results and exclude the ones you are not interested in.

For example, this query to /questions:
          /2.2/questions?tagged=notifications&site=stackapps

returns:

{ "items": [ {
      "title": "Top Bar for Chat Rooms"
    }, {
      "title": "Get our Stack Exchange inbox as native notification on Chrome"
    ...
    }, {
      "closed_date": 1382175473,
      "title": "Mark notification/inbox item as read"
    }, {
      "title": "Trying to get the Total results count crashes the /notifications path"
    ...
    } ],
  "total": 13
}

Your code would loop through that and reject items where typeof closed_date != "undefined.

---

Return only open questions:

For such "complex" queries, the /search/advanced route was added.

There you have two options:

1. You can use the closed=False parameter provided:
   /2.2/search/advanced?closed=False&tagged=notifications&site=stackapps

2. Or you can leverage the q parameter -- which mimics much of the functionality of the website search:
   /2.2/search/advanced?q=closed:no&tagged=notifications&site=stackapps