Is it possible to convert text column to json on the fly then query against it in postgres?

Question

I have to work with a text column, but its content is json format. An example:

{"company":"company name","entityName":"entity name","asOfDate":1604725200000}

Right now, I am using LIKE to get the results I want:

select distinct a.company_name from company_table a
where a.json_field LIKE '%' || ?1 || '%'

I would like to be able to query the json directly:

select distinct a.company_name from company_table a
where a.json_field ->> company = ?1

A third option would be getting all the rows, then use code to parse through them, I'm fairly certain that the growth of table is low and won't reach like 10k/year.

While the LIKE method works, I don't know if it's 100% correct.

Any suggestions?

Answer 1

Just cast it:

where (a.json_field::jsonb) ->> company = ?1

This will error if your string is not valid JSON.

I would recommend fixing your schema, and convert that column to JSON once and for all, so you don't need to worry about this anymore. You can do this in a single statement:

alter table company_table 
    alter column json_field type jsonb 
    using json_field::jsonb;