How to make an array selection in a JSON field?

Question

PostgreSQL

Right now the query is only looking in the first element of the array, but I need to iterate over the entire array in a JSON field

attr = Column(db.JSON)

unit.attr = [
  {'name': 'name1', 'date': '01.01.2018'},
  {'name': 'name2', 'date': '01.01.2015'}
]


query = query.filter(Unit.attr[0]['date'].cast(db.String).cast(db.Date).between(date_begin, date_end))

How to specify it in the code?