# Elastic Painless Scripted Field On Null/Missing Value

This post shows how to use elastic painless language in scripted field to work on documents' keys which might not exist in some documents.

## Parsing analyzed field in Painless

Suppose we have following 2 documents in elastic:

```
[{
    "kye1": "value1",
    "key2": {
        "key22": "value22"
    }
}, {
    "key1": "valuex"
}]
```

The key `key22` in the first document can be accessed by `doc['key2.key22'].value`. If we use this script in the scripted field, we will see a null value for all the documents. This is because the second document doesn't have the key `key22`, painless language will throw an error. This [github issue](<https://github.com/elastic/elasticsearch/issues/33816>) is discussing how to return a default value if it is missing.

To workaround this, I found a solution from this [github issue](<https://github.com/elastic/elasticsearch/issues/24125#issuecomment-375874356>). We should check the null value each time.

The script should be:

```
(params._source.key2 == null) ? '' : ( (params._source.key2.key22 == null) ? '' : (params._source.key2.key22) ))
```

> [!WARNING]
>
> Parsing documents by `params._source` is [very slow](<https://findingdata.rocks/elasticsearch-scripting-understanding-the-difference-between-doc-and-params/>). It's not cached, and is calculated in real-time each time.

> [!WARNING]
>
> The fields calculated by the scripted field is not searchable.