Value functions

This module contains several miscellaneous functions that can be used with values of any type.

.chain()

Available since: v2.0.0

The .chain() method takes the output of an expression upon which the user can call an anonymous function (closure).

API DEFINITION
value.chain(|$val_name| @closure_body) -> value;

Any value can be followed with the .chain() syntax, after which an anonymous function (closure) can be written to perform an operation on it.

'SurrealDB'.chain(|$n| $n + ' 2.0');
-- 'SurrealDB 2.0'

The function is only called using the . operator (method syntax) and, as the name implies, works well within a chain of methods.

{ company: 'SurrealDB', latest_version: '2.0' }
    .chain(|$name| <string>$name)
    .replace('SurrealDB', 'SURREALDB!!!!!');

Response
"{ company: 'SURREALDB!!!!!', latest_version: '2.0' }"

For a similar function that allows using a closure on each item in an array instead of a value as a whole, see array::map.

value::diff

Available since: v2.0.0

The value::diff function returns an object that shows the JSON Patch operation(s) required for the first value to equal the second one.

API DEFINITION
value::diff(value, value) -> array<object>

The following is an example of the value::diff function used to display the changes required to change one string into another. Note that the JSON Patch spec requires an array of objects, and thus an array will be returned even if only one patch is needed between two values.

RETURN 'tobie'.diff('tobias');

Output
[
	{
		op: 'change',
		path: '/',
		value: '@@ -1,5 +1,6 @@
 tobi
-e
+as
'
	}
]

An example of the output when the diff output includes more than one operation:

{ company: 'SurrealDB' }.diff({ company: 'SurrealDB!!', latest_version: '2.0', location: city:london });

Response
[
	{
		op: 'change',
		path: '/company',
		value: '@@ -2,8 +2,10 @@
 urrealDB
+!!
'
	},
	{
		op: 'add',
		path: '/latest_version',
		value: '2.0'
	},
	{
		op: 'add',
		path: '/location',
		value: city:london
	}
]

value::patch

Available since: v2.0.0

The value::patch function applies an array of JSON Patch operations to a value.

API DEFINITION
value::patch(value, patch: array<object>) -> value

LET $company = {
    company: 'SurrealDB',
    latest_version: '1.5.4'
};

$company.patch([{
		'op': 'replace',
		'path': 'latest_version',
		'value': '2.0'
}]);

Response
{
	company: 'SurrealDB',
	version: '2.0'
}