Generating rules for the fields with default values

[manky]

Q	A
Is bugfix?	❌
New feature?	✔️
Breaks BC?	❌

This may sound unimportant, but if you are using yii\behaviors\AttributeTypecastBehavior and the cast depends on the rules() method of your model, for example, fields validated via yii\validators\NumberValidator and without any value will be cast to integer/float. So the value of the empty fields will become 0

An important part is that default rules should be at the beginning of the rule list.

[what-the-diff]

PR Summary

• Introduction of $nullable and $defaultValues Arrays
  We have introduced two new arrays - $nullable and $defaultValues. These arrays are used to specify if certain columns are allowed to be null and to provide default values to some columns respectively.

• Updating $nullable for Specific Columns
  We have made changes in the code that allow us to ensure that, for specific columns which are allowed to be null, there can be entries in the $nullable array indicating this.

• Populating $defaultValues for Given Columns
  Changes have also been made that allow us to provide default values for specific columns, if any. These are then recorded in the $defaultValues array.

• Added Validation for Nullable and Default Value Columns
  New validation rules have been included to check the columns that are nullable or have default values. This helps in reducing errors and ensuring data integrity.

• Modification in Database Driver Name Checking
  A modification has been made in the condition that checks the database driver name. Now, it specifically checks if the driver's name is 'pgsql' and the column type is 'integer'. This ensures more accurate and efficient checking of database driver specifications.

[samdark]

Looks good. Please add a line for changelog. Thanks.

[manky]

The line has been added to the changelog. Thanks.

[samdark]

Thank you!