Bookshelf: query builder: how to use like operator with json column? - json

Question

I'm using bookshelf with postgresql database
Information is a column of type json.
I want to retrieve all column that are like '%pattern%'
With sql query i use
select * from table where information::text like '%pattern%';
I want to do that with bookshelf query builder
model.query(function(qb) {
qb.where('information', 'LIKE', '%pattern%')
}).fetch()
But it didn't work and i can't find how to do it in bookshelf docs
Any idea?

Answer 1

The tricky part here is, although you might think that JSON (and JSONB) columns are text, they aren't! So there's no way to do a LIKE comparison on one. Well, there is, but you'd have to convert it to a string first:
SELECT * FROM wombats WHERE information #>> '{}' LIKE '%pattern%';
which is a really terrible idea, please don't do that! As #GMB points out in the comments, JSON is a structured format that is far more powerful. Postgres is great at handling JSON, so just ask it for what you need. Let's say your value is in a JSON property named description:
SELECT * FROM wombats
WHERE (information->'description')::TEXT
LIKE '%pattern%';
Here, even though we've identified the correct property in our JSON object, it comes out as type JSON: we still have to cast it to ::TEXT before comparing it with a string using LIKE. The Bookshelf/Knex version of all this would look like:
model
.query(function(qb) {
const keyword = "pattern";
qb.whereRaw(`(information->'description')::TEXT LIKE '%${keyword}%'`)
})
.fetch();
Apparently this part of the raw query cannot be parameterized (in Postgres, at least) so the string substitution in JavaScript is required. This means you should be extra careful with where that string comes from (ie only use a limited subset, or sanitise before use) as you're bypassing Knex's usual protections.