Add function support

[nathggns]

These commits add SQL function support across Scaffold's database system.

Usage

<?php
// Get a random user
$users = new ModelUser();
$users->find[
    'order' => [
        Database::func_random()
    ],
    'limit' => 1
]);

// Gets the count using our system
$users = new ModelUser();
$users->alias('count', Database::func_count('*'));
echo $users->count;
// 1

$user = new ModelUser();
$user->create([
    'name' => 'Charlie'
]);
echo $users->count;
// 2

$users = new ModelUser();

echo $users->max('id');
// 2

echo $users->min('id');
// 1

Changelog

This pull request added the following two classes.

• DatabaseQueryBuilderFunction
  • Base class for generating strings for functions in Scaffold. Has a method for each of the languages Scaffold supports, currently only SQL, and has a map of fallbacks (SQLite => 'SQL).
• DatabaseQueryBuilderFunctionRandom
  • An example of a function that doesn't use it's name (random) to generate the string. Instead, it returns a custom string RAND. We'll probably need to add a lot more of these.

It adds the following service

• database.query.builder.function
  • Checks if a custom class exists for this function, and returns an instance of that custom class, or the base DatabaseQueryBuilderFunction class.

Database::__construct has been modified to not need an instance of Config passed to it if it has been initiated before.

Dynamic has been modified to support being an alias for a class method. Simply pass the same array you'd pass to call_user_func

The following methods have been added

• Database::func_*
  • This creates the object that is recognised as a function across the system. The object has only one method, as, which allows you to alias the function (generating SQL strings like SELECT COUNT(*) AScountFROM ...)
• DatabaseQueryBuilder::val
  • This is a chained helper for the vals section of query_opts for SELECT statements.
• DatabaseQueryBuilder::is_func
  • Tests if a value is a valid function object.
• DatabaseQueryBuilder::func
  • Converts a function object to the string required.
• ModelDatabase::value
  • __get is now an alias for this. We can now pass function objects to it. Results of functions will never be cached.
• ModelDatabase::alias
  • Alias properties. Allows you to call functions using properties.
• ModelDatabase::__call
  • __call will create function objects with the name of the function and any args passed to it, which is then passed to ModelDatabase::func (The function that ModelDatabase::value uses for function objects)
• ModelDatabase::random
  • Returns a single random row.

The following bugs have been fixed

• Database::__callStatic successfully passes unknown functions through to the driver.

[nathggns]

This fixes #85

[andrewhathaway]

Using Database::func_random() isn't too nice. Would be nice to have maybe something like the following, not sure if it's possible.

<?php
$user->random([]);

Where the array would be the where clauses.

[nathggns]

I never said that helpers like that wouldn't be possible, you could even define those yourself. I'll define some later, including that one.

However, I was thinking of using __call for functions as columns.

[andrewhathaway]

Ah. Awesome.

[nathggns]

@AndrewHathaway You can now pass functions to ModelDatabase by simply calling the function. ModelDatabase::max for example. You can pass arguments too.

[nathggns]

@ClaudioAlbertin Question. Should aliases functions be part of the export array?

[andrewhathaway]

Nice work. :)

[nathggns]

The random function uses the preexisting conditions. Set conditions, then use random.

[nathggns]

Merging. Any complaints about this implementation should be made in a separate issue.