Create Custom Dimension by extracting field from JSON

[sshawish]

I have a column in BigQuery of type JSON, and I want to create a custom dimension from a field inside the JSON.

For example, I have the following JSON:

{"name": "My name", "lastName": "My lastName"}
I want to create a custom dimension called name, using something like:

JSON_VALUE(responseValue, "$.name")

I don't want to create the dimension in LookML, it needs to be created only in Explore using a Custom dimension