Creating a new column in Laravel Schema builder, using the value of existing column by default

Question

I'm trying to create a table, which contains an "email_address" field and an "activation hash" field. The default value of "activation hash" field should be

sha1(microtime().email_address))

Is it possible to set this up using laravel migrations and how can I do this?

Surely, i should say, that i'm using postgres as DB engine

Since microtime is a PHP function, no. But you can use a Model Event for it: https://laravel.com/docs/master/eloquent#events — aynber, Sep 08 '16 at 12:54
Maybe you can start here: http://stackoverflow.com/questions/39177303/laravel-5-x-database-triggers-and-possible-best-practices — The One and Only ChemistryBlob, Sep 08 '16 at 12:56

score 0 · Answer 1 · answered Sep 08 '16 at 13:01

Most database engines are limited as to what values can be set as a default to columns. Depending on your database engine, you might be able to do it via an event/trigger but it's easier and arguably better to solve this at an application level with Eloquent events.

score 0 · Answer 2 · answered Sep 08 '16 at 13:03

When I need to do something like this, I split the code in 2 pieces:

Create the column (using Schema Builder)
Set the value (over PHP, loading all models and updating one by one in a foreach)

Note: Both steps can be done at migration file.

You can't do it entirely at MySQL (if you are using MySQL) query since it doesn't have a microtime() function.

But I found this UDF implementation for microtime() on MySql:

https://github.com/JohannesMP/MySQL-udf-microtime

If you are not updating a huge dataset, I would stick with the first solution. But if you are updating a huge dataset, so the MySQL implementation will be faster.

Creating a new column in Laravel Schema builder, using the value of existing column by default

2 Answers2