# Validate JSON fields

JSON imports can validate a row schema and, separately, typed paths inside a JSON document. Choose the contract that matches the stored value.

## Row columns

Before INSERT FORMAT, create destination columns for the row fields. A JSON object field assigned to UInt64, for example, must convert to that declared integer range.

## Typed document paths

Use `JSON(path Type, ...)` when one column stores an object with selected typed paths:

```sql
CREATE TABLE typed_json
(
    doc JSON(user_id UInt64, details.price Decimal(18, 2))
);
INSERT INTO typed_json VALUES
    ('{"user_id":7,"details":{"price":"12.50"}}');
```

```sql
SELECT doc.user_id, doc.details.price
FROM typed_json
FORMAT csv;
```

```text
7,12.50
```

## Missing and conflicting fields

A missing or explicit-null declared path uses its type default. Nullable paths remain NULL. An object path whose parent is a conflicting scalar is rejected; undeclared members remain in the document.

See [JSON](https://coordinatordb.com/docs/reference/data-types/json) for type-hint declarations and [JSON functions](https://coordinatordb.com/docs/reference/functions/regular-functions/json-functions) for extraction and transformations.