# JSONata Advanced Functions: $filter, $exists, $not, $map

**URL:** https://community.glideapps.com/t/jsonata-advanced-functions-filter-exists-not-map/72468
**Category:** Community Resources
**Tags:** api, query, call-api, json
**Created:** [April 10, 2024, 8:53pm UTC](https://community.glideapps.com/t/jsonata-advanced-functions-filter-exists-not-map/72468 "2024-04-10T20:53:42Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Darren\_Alderman](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/darren_alderman/32/66660_2.png) [@Darren\_Alderman](https://community.glideapps.com/u/Darren_Alderman)
#### Post date: [April 10, 2024, 8:53pm UTC](https://community.glideapps.com/t/jsonata-advanced-functions-filter-exists-not-map/72468/1 "2024-04-10T20:53:42Z")

</div>

Glide uses [JSONata](https://docs.jsonata.org/overview.html) in to query JSON in the [Query JSON column](https://docs.jsonata.org/overview.html).

I’ve understood the simple syntax of mapping through arrays and objects.

- `$rows[2].Name` - Returns the name of the 3rd item in the array
- `$rows[].Company.Name` - Returns all Company Names in the array

However using JSONata functions has been challenging, but I figured on one example I’ll share with you here. I wanted to take all the rows returned from Glide’s [Get Rows endpoint](https://docs.jsonata.org/overview.html) and get the Glide row IDs of all rows with an empty value in a column. Here’s how to build it.

> **Sample JSON**
>
> `[{ "rows":[{ "$rowID":"qo9E.QS4StCnt-l8NGq3RA", "tQowu":"chvcRSSPTJaaoK2zbhGplQ", "$rowIndex":"W4", "Name":"Darren Test", "7gs1N":"Concert", "yTkLn":"Circus", "XsO9S":"Candy", "Fi3FK":"People pay for the app", "SlTnS":"They abandoned the project", "1TME8":"They have users", "EG3td":"They are onboarding their team", "g1tSc":"They won't respond", "LJwsZ":"They are excited", "McQlI":"The are rigid", "GQca3":"They are skeptical" }, { "$rowID":"8rlmKXWlT2a05x3qPw851A", "$rowIndex":"WI", "Name":"sdfg" }, { "$rowID":"a.1W8y-MCQbqYMuhpaslnxg", "$rowIndex":"WD", "Name":"Namne" }, { "$rowID":"P3sGMXI6Q.S5HCIUhfWGiQ", "tQowu":"chvcRSSPTJaaoK2zbhGplQ", "$rowIndex":"W5", "Name":"Acme Inc" }, { "$rowID":"UEFhY5xyQjeWWp.i.FB2XQ", "tQowu":"chvcRSSPTJaaoK2zbhGplQ", "$rowIndex":"WL", "Name":"go" }, { "$rowID":"fz3MGJ7AS7KUx7WZ-kZGjA", "$rowIndex":"WG", "Name":"goober" }, { "$rowID":"a.MLAIGa6RzKe83ZjzpyM9Q", "tQowu":"chvcRSSPTJaaoK2zbhGplQ", "$rowIndex":"WF", "Name":"dfghdfgh" }, { "$rowID":"7LeoFzHqQ22jSvV2HN8neA", "$rowIndex":"WH", "Name":"dddd" }, { "$rowID":"X88ibzdNTbizii06PYNczw", "$rowIndex":"WE", "Name":"good" }, { "$rowID":"L908hzGySa-r58CCT3knNQ", "$rowIndex":"WJ", "Name":"uuuu" }, { "$rowID":"FcjD8DNMQYGy026zEsoo9g", "tQowu":"chvcRSSPTJaaoK2zbhGplQ", "$rowIndex":"WK", "Name":"just" }] } ]`

### JSONata Query

```auto
$map(
   $filter(
      $.rows, 
      function ($v) {
         $not( $exists($v."tQowu") )
      }
   ),
   function($v) {
       $v."$rowID"
   }
)

```

- `$.rows` gets the array of rows from the api response
- `$exists` returns true if the `"tQowu"` field is not empty
- `$not` negates what’s returned from `$exists` allowing me to check if the field IS empty
- `$filter` checks all rows with this logic only returning rows where the field is empty
- `$map` maps the rows to the `$rowID`

_Note: $map isn’t required in this use case, this also works:_

```auto
   $filter(
      $.rows, 
      function ($v) {
         $not( $exists($v."tQowu") )
      }
   )."$rowID"

```