How to parse JSON with ParadeDB in PostgreSQL

How do I safely convert text columns to JSONB using parse_json in PostgreSQL?

parse_json() converts a text column or string literal into a validated JSONB value so you can query it with native JSON operators.

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Description

What problem does parse_json solve?

parse_json() safely converts VARCHAR or TEXT that contains JSON into PostgreSQL’s JSONB type. This lets you run ->, ->>, and jsonb_path_* functions without first altering the table schema.

How does parse_json work internally?

The function is a thin wrapper around PostgreSQL’s jsonb parser compiled into the ParadeDB extension.It returns NULL or throws an error when the input is not valid JSON, depending on the chosen mode.

What is the full syntax for parse_json?

See the next section for the complete signature, optional parameters, and default behaviors.

When should I call parse_json?

Use it in SELECTs, WHERE filters, or materialize its result into a generated column. Typical cases include ad-hoc reporting, backfills, or building a view on semi-structured ecommerce logs.

Can I enforce strict validation?

Yes.Pass the optional strict flag (‘strict’) to force the function to raise an exception instead of returning NULL on malformed JSON.

Example: strict vs. lenient mode

Lenient: SELECT parse_json(col) FROM raw_events; Strict: SELECT parse_json(col, 'strict') FROM raw_events;

How do I parse JSON in an ecommerce database?

The code example below converts the ‘metadata’ text column in Orders into JSONB and extracts the payment method.

Best practices for using parse_json

Prefer casting once in a view or generated column.Index the generated JSONB expression with GIN if you filter frequently. Monitor failed parses via a NOT NULL check in STRICT mode.

Common pitfalls and how to avoid them

See the mistakes section for quick fixes to typical errors like double-encoding or missing quotes.

Why How to parse JSON with ParadeDB in PostgreSQL is important

How to parse JSON with ParadeDB in PostgreSQL Example Usage


-- Parse the JSON order_details column and filter by payment method
SELECT o.id,
       o.order_date,
       pj->>'payment_method' AS pay_method,
       pj->'items' -> 0 ->> 'product_id' AS first_product
FROM   (
        SELECT id, order_date, parse_json(order_details) AS pj
        FROM   Orders
       ) AS o
WHERE  pj->>'payment_method' = 'credit_card';

How to parse JSON with ParadeDB in PostgreSQL Syntax


SELECT parse_json(source_text [, 'strict']) AS json_value
FROM   your_table;

-- Parameters
source_text TEXT/VARCHAR | The column or literal containing JSON
'strict'   TEXT          | Optional. When supplied, invalid JSON throws ERROR instead of returning NULL

-- Ecommerce example
SELECT id,
       parse_json(order_details)                AS order_json,
       parse_json(order_details)->>'status'     AS order_status,
       parse_json(order_details, 'strict')      AS strict_json
FROM   Orders;

Common Mistakes

Mistake: Casting with ::jsonb before parse_json — SELECT parse_json(col::jsonb) FROM t; Why it’s wrong: parse_json expects TEXT. Fix: remove the cast and call parse_json(col).
Mistake: Forgetting to index parsed JSON — filtering without a GIN index leads to slow queries. Fix: CREATE INDEX ON Orders USING gin (parse_json(order_details));