Database Reference
In-Depth Information
•
Node.js
users, and other users who want to use Javascript for building network
applications, will appreciate that PL/V8 and Node.js are built on the same Google
V8 engine and that many of the libraries available for Node.js will work largely
using Node.js modules and modules you build easier to reuse in PL/V8.
You can find several examples on our site of PL/V8 use, some even involving copying
fairly large bodies of JavaScript code that we pulled from the Web and wrapping them
in a PL/V8 wrapper, as detailed in
Using PLV8 to build JSON Selectors
.
The PL/V8
family mates perfectly with web applications because much of the same client-side Java‐
Script logic can be reused. More important, it makes a great all-purpose language for
developing numeric functions, updating data, and so on.
Basic Functions
One of the great benefits of PL/V8 is that you can use any JavaScript function in your
PL/V8 functions with minimal change. For example, you'll find many JavaScript ex‐
amples on the Web to validate email address. We arbitrarily picked one and made a PL/
V8 out of it in
Example 8-16
.
Example 8-16. Using PL/V8 to validate email address
CREATE
OR
REPLACE
FUNCTION
validate_email
(
email
text
)
returns
boolean
as
$$
var
re
=
/
\
S
+@
\
S
+
\
.
\
S
+/
;
return
re
.
test
(
email
);
$$
LANGUAGE
plv8
IMMUTABLE
STRICT
;
Our code uses a JavaScript regex object to check the email address. To use the function,
see
Example 8-17
.
Example 8-17. Calling PL/V8 email validator
SELECT
email
,
validate_email
(
email
)
AS
is_valid
FROM
(
VALUES
(
'alexgomezq@gmail.com'
)
,(
'alexgomezqgmail.com'
),(
'alexgomezq@gmailcom'
))
AS
x
(
email
);
which outputs:
email | is_valid
----------------------+----------
alexgomezq@gmail.com | t
alexgomezqgmail.com | f
alexgomezq@gmailcom | f
Although you can code the same function using the PL/pgSQL and PostgreSQL's own
regular expression support, we guiltlessly poached someone else's time-tested code and
wasted no time of our own. If you're a web developer and find yourself having to validate
