How do I modify fields inside the new PostgreSQL JSON datatype?

Question

With postgresql 9.3 I can SELECT specific fields of a JSON data type, but how do you modify them using UPDATE? I can\'t find any examples of this in the postgresql documenta

Answer 1

If your field type is of json the following will work for you.

UPDATE 
table_name
SET field_name = field_name::jsonb - 'key' || '{"key":new_val}' 
WHERE field_name->>'key' = 'old_value'.

Operator '-' delete key/value pair or string element from left operand. Key/value pairs are matched based on their key value.

Operator '||' concatenate two jsonb values into a new jsonb value.

Since these are jsonb operators you just need to typecast to::jsonb

More info : JSON Functions and Operators

You can read my note here