How to convert array to String

[deni]

Hi,

From one of the tasks of the DQL course in university:

Data Types

Starting with the below DQL Query, what data type are the following fields:

• related_entity_ids
• dt.davis.is_duplicate
• event.start

Afterwards, modify the query to cast the k8s.container.name field to a String.

I checked the requested types and the type of the k8s.container.name is an array. I tried the following:

fetch events
| filter event.kind == "DAVIS_PROBLEM"
| fields k8s.container.name
| filterOut isNull(k8s.container.name)
| fieldsAdd test = asString(k8s.container.name)

The value of the test column is null. I searched in the documentation, but didn't find anything like arrayToString(arr, delimiter) or similar. 

Can you help me with this?

Regards, Deni

[krzysztof_hoja · Accepted solution]

Unfortunately there is no function where you can specify new delimiter. There is however toString function. This example should explain how it works and how to achieve what you need:

data record(arr=array("s1","s2","s3"))
| fieldsAdd merged = toString(arr)
| fieldsAdd merged2 = replaceString(merged,"""["""","")
| fieldsAdd merged2 = replaceString(merged2,""""]""","")
| fieldsAdd merged2 = replaceString(merged2,"""", """","/")

[deni]

Ahaaa, I tried asString, but now I see in the documentation that all as... functions just verify the type and return null otherwise. If I want to cast, I need to use the to... functions — in this case toString.

Thanks also for the extra tips on how to set a custom delimiter 🙂