The ALTER FIELD statement is used to change or entirely drop clauses of a defined field on a table.
Statement syntax
SurrealQL Syntax
ALTER FIELD [ IF EXISTS ] ON [ TABLE ] @table
[
DROP TYPE |
DROP FLEXIBLE |
DROP READONLY |
DROP VALUE |
DROP ASSERT |
DROP DEFAULT |
DROP COMMENT |
DROP REFERENCE |
FLEXIBLE |
READONLY |
REFERENCE |
TYPE @type |
VALUE @value |
ASSERT @expression |
DEFAULT [ ALWAYS ] @expression |
[ PERMISSIONS [ NONE | FULL
| FOR select @expression
| FOR create @expression
| FOR update @expression
| FOR delete @expression
] ]
COMMENT @string |
]Examples
As ALTER FIELD contains the same clauses available in a DEFINE FIELD statement, be sure to see that page for more examples.
Here is one example in which the name field is defined for a record user:
DEFINE FIELD name ON user TYPE string;Later on, a database-wide parameter is defined to disallow certain user names. This can be followed up with an ALTER FIELD statement to add the ASSERT clause to it.
DEFINE PARAM $DISALLOWED_NAMES VALUE ["Lord British", "Lord Blackthorn"];
ALTER FIELD name ON user ASSERT $value NOT IN $DISALLOWED_NAMES;
CREATE user SET name = "Lord British";Output
"Found 'Lord British' for field `name`, with record `user:yn4yttkg5w683q2937bq`, but field must conform to: $value NOTINSIDE $DISALLOWED_NAMES""