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Database Models

Database models are simplified implementation of ActiveRecord. Every table in database should have its own PHP class which allows you to easily select, insert, update or delete record from that table.

Before continuing with models, make sure you have properly configured database connections.

Creating Model Class

To map your PHP class to table in database, simply create class that extends \Koldy\Db\Model.

For example, let's say you create file on library/Db/User.php:


namespace Db;

use Koldy\Db\Model;

class User extends Model

Your \Db\User model is created and ready to use, but since there's nothing else configured in model, framework will do assumptions which might not be correct. For the example above, framework assumes:

  1. Table name is the same as class name. If class name is \Db\User, then assumed database table name is db_user.
  2. Database connection is not set, so connection used in this model will be the first connection defined in configs/database.php.
  3. Primary key is not configured, so framework assumes you have integer id column which is primary key in your table.
  4. Based on assumption 3, framework assumes that your integer id is auto incrementing on each insert.

If these assumptions are good in your case, then there's really nothing else you need to do.


To override framework's assumptions from above, you should define protected static properties in your class.

Database Table Name

protected static $table = 'user';

If you define $table, framework will know that it should use table named user and not db_user.

Database Connection Adapter

If you take a look on database configuration example and you want your model to connect to admin database, then simply add:

protected static $adapter = 'admin';

Primary Key

If your primary key column is not named id, then define its name like:

protected static $primaryKey = 'user_id';

If you're using multi-column primary key in your database table, then define it like array:

protected static $primaryKey = ['user_id', 'group_id'];

Auto Increment

Framework always think you have auto-increment primary key because this is common behaviour in most cases so you should define this in any other case.

protected static $autoIncrement = false;

Set $autoIncrement to false if there's no auto-increment column in your table. If your table has multi-column primary key, you should still set $autoIncrement to false.

PostgreSQL Increment Sequence

When working with PostgreSQL, creating auto increment column creates named sequence which is by default formatted like [tableName]_[pkName]_seq. This name has to be used when fetching last increment ID. Framework handles this for you, but if you ever encounter on case where you can't use standard sequence name, then sequence name should be defined as:

protected static $autoIncrement = 'my_pk_seq';

If your sequence is not named by standard and you don't define its name with $autoIncrement, then you won't be able to get primary key value when you insert new record using Model::create() method.

Be aware that no error will be raised in this case.

Model's Configuration Example

This is how your configuration might look like. We'll use this example for next examples. Let's assume this table has id, first_name, last_name and created_at. We'll create getters for those as well.


namespace Db;

use Koldy\Db\Model;

class User extends Model
    protected static $table = 'user';
    protected static $adapter = 'admin';
    protected static $primaryKey = 'id';
    protected static $autoIncrement = true;

    public function getId(): int
        return (int)$this->id;

    public function getFirstName(): string
        return $this->first_name;

    public function getLastName(): string
        return $this->last_name;

    public function getCreatedAt(): string
        return $this->created_at;

Creating / Inserting

To insert data in your table, use create static method:

$user = User::create([
    'first_name' => 'John',
    'last_name' => 'Smith',
    'created_at' => gmdate('Y-m-d')

$user is now instance of \Db\User class. What framework actually did was:

  1. Inserted record in database
  2. Fetched auto increment value from database, put it in your model and returned result like this:
return new User([
    'id' => 5,
    'first_name' => 'John',
    'last_name' => 'Smith',
    'created_at' => '2017-08-20'

As you can see, initializing new instance of the class doesn't do anything. It just takes data and holds it until you call next method. Actual insert was performed using static create method.

Alternative way of inserting records in database is the other way around: first create model instance and then insert it:

$user = new User([
    'first_name' => 'John',
    'last_name' => 'Smith',
    'created_at' => '2017-08-20'


Be aware that if your model contains primary key value and you call save() method, it'll perform UPDATE and not INSERT.


Now that you inserted model and have its instance, you can change it's properties:

$user->first_name = 'Michael';

Calling save() will perform update if there are fields different than the original data meaning that framework won't touch the database if there is no need to. Save can perform UPDATE only if model contains primary key value.

In many cases, you'll want to update records in table without making model's instance first. To do that, use static update method on \Db\User:

User::update(['first_name' => 'Derek'], 1);

The above example will update first_name to Derek on the record where primary key is 1.

If you want to update record by some other criteria, simply pass it as array:

User::update(['first_name' => 'Derek'], ['last_name' => 'Smith']);

This example would set first_name to Derek on all records where last_name is Smith. To pass even more complex WHERE statements, use instance of WHERE.


When you have your model's class instance ready, you can use destroy method to delete it from server.


This will delete record from database, but $user instance will remain with its original data inside.

If you want to delete one or more records from database without making model's instance first, simply use delete method on \Db\User:


The above example will delete record in user table where primary key is 1.

Same as update, you can pass more complex where statements:

User::delete(['first_name' => 'Derek', 'last_name' => 'Smith']);

The above example will delete all records where first_name is Derek and last_name is Smith. To pass even more complex WHERE statements, use instance of WHERE.

Retrieving Models

Now that you know how to manipulate with records in database, you should see how easy you can retrieve records back from database.

Retrieve One Record

To fetch one record and get the model back, you can use your primary key:

$user = User::fetchOne(1);

If there's a record in user table with primary key id=1, you'll get back instance of \Db\User filled with all columns from database. If there's no record in database, you'll get null back.

You can pass different conditions:

$user = User::fetchOne('first_name', 'John');
// same as:
$user = User::fetchOne(['first_name' => 'John']);

Be aware that if you have more than one record where this condition is met, you'll still get one record back and its model instance, and it's gonna be the first record database decides to give you back.

When fetching one record from database, framework grabs the whole table row back using * in SELECT statement. In same rare cases, you'll want to get only some of the columns. You can define that as third parameter:

$user = User::fetchOne('id', 1, ['id', 'first_name', 'last_name']);

Don't forget your primary key column.

Sometimes, you might want to stop your system from execution if there's nothing in database under given parameters. In this case, use:

$user = User::fetchOneOrFail(1);

In this example, you can be sure that you'll get filled \Db\User back. If record wasn't found, framework will throw \Koldy\Db\Exception\NotFoundException.

When you have your $user model instance, you can access your columns directly:

echo $user->last_name;

We prefer that you create getters for all columns (properties) you tend to use.

If you want to get all data as array, use getData() method:


Retrieve Multiple Records

To fetch one or more records at once, you can use simplified fetch method, or you can use query builder for more complex cases.

Static method fetch accepts few parameters:

  1. Where statement, which can be simple as integer, string, array, or instance of WHERE
  2. Array of fields you want to get back or all if set null
  3. Name of the column you want to order by
  4. Order direction, asc or desc
  5. How many records you want to fetch
  6. From which record you want to start

5 and 6 are used for LIMIT.

$users = User::fetch(['last_name' => 'Smith'], null, 'first_name', 'ASC', 100, 50);

This example will fetch all records where last_name is Smith, it'll fetch all columns and array you get back will be sorted by first_name ascending and you'll take 100 records, starting from 50th record. What you'll get back is array of \Db\User instances.

If there are no records in database, you'll get back empty array.

To perform much complex queries, see select query builder which can be prepared with your model and executed:

$users = User::select()
    ->where('last_name', 'Smith')
    ->where('id', '>', 500)
    ->orderBy('last_name', 'ASC')
    ->orderBy('first_name', 'DESC')
    ->limit(0, 100)

Retrieve One Value

You can easily retrieve value from one column of one row. Let's say there's birthday column in user table and you want to retrieve birth date of user with id=5:

$birthday = User::fetchOneValue('birthday', 5);

There's User::fetchOneValueOrFail() method as well that ensures you get something back, otherwise it'll throw \Koldy\Db\Exception\NotFoundException.

But, let's say there's more records you need to query and it all depends on order. For example, let's say you want to retrieve last name of first created John in table:

$lastNameOfFirstJohn = User::fetchOneValue('last_name', ['first_name' => 'John'], 'created_at', 'asc');

Retrieving Array Of Values

For some reason, let's say you want to get all IDs for all Johns in user table:

$johnIds = User::fetchArrayOf('id', ['first_name' => 'John'], 'created_at', 'asc', 10);

If records with "John" exists, then $johnIds will be array of IDs, sorted by created_at ascending and limited for up to 10 records. This is useful if you plan to use these IDs in some other query.

Retrieving Key-Value Pairs

Let's say you have a table with the list of countries in country table: country_name and its primary key id. You want to build <select> options so end user can choose one country. To retrieve these key-value options from database, simply use:

$keyValuePairs = Country::fetchKeyValue('id', 'country_name', null, 'country_name', 'asc');

You'll get all key-value pairs where key is country's id, value is country's name, ordered by country_name ascending.

Retrieving All Records From Table

To retrieve all records from table, simply use your model and all method. If needed, just pass parameters so database knows how to sort your results.

$allUsers = User::all('last_name', 'asc');

$allUsers will be array of User model instances, ordered by last_name ascending.


You can use model's class for database transactions as shorthand. Imagine that you have a lot of database models and several database connections. Some models connect to one database, some to another. Then, if you want to do a transaction, you need to know which connection you should use.

Since model has database connection configuration, you can use model without need to think which connection is that.

try {
} catch (\Koldy\Db\Exception $e) {

Query Builders

You'll encounter on many cases when you want to create custom select query that starts from a model's table. If you check the query builders documentation, you'll see that when you want to create select statement on other-than-default database connection, you would do something like:

$select = new \Koldy\Db\Select('user');
$select->where('id', '<', '10');
$result = $select->fetchAll();

To speed up this process, you can use your model's class as shorthand:

$result = User::select()->where('id', '<', '10')->fetchAll();

Counting Records

You can use your model's class to simply count how many records is present in table.

$totalCount = User::count();

If you don't pass condition to count method, you'll get total number of records in user table. Otherwise, you can pass array of conditions or instance of WHERE just like everywhere else to limit count on your condition(s).

Checking Record Uniqueness

You'll run into case when you want quickly check if some record already exists, like when you have a form for users to sign up and you want to check if given email address already exists.

Let's assume that our example model (User) has email column which is unique. To check if entered email already exists, use:

$isDuplicate = User::isUnique('email', 'my@email.com');

So, $isDuplicate will be true if you have a record with email=my@email.com or false if there's no record with entered email address.

Now, imagine a case when our end user from above successfully created its account, signed in, went to account settings and wants to change its email address. You open up a pre-populated form with the user's email address. When user submits that form, you'll either get the email address that wasn't changed or entirely new address. In both cases, you would probably want to treat this case as success, meaning that you must check if email already exists, but ignoring its own email address.

To do that, pass exception value as third parameter:

$isDuplicate = User::isUnique('email', 'new@email.com', 'my@email.com');

Fourth parameter of isUnique method is exception field name. In case when user wants to update its own email address, you probably have the user's ID remembered in session, meaning that you can check if email is unique by ignoring his own record in table by its id. Let's say user's ID is 5:

$isDuplicate = User::isUnique('email', 'new@email.com', 5, 'id');

This example will check if there is record in user table where email is new@email.com and where id is not 5.

Method isUnique is used in Validators as well.