Doctrine_manual-1-2-en

Chapter 7: Defining Models 56
Type modifiers
Within the Doctrine API there are a few modifiers that have been designed to aid in optimal
table design. These are:
• The notnull modifiers
• The length modifiers
• The default modifiers
• unsigned modifiers for some field definitions, although not all DBMS's support this
modifier for integer field types.
• collation modifiers (not supported by all drivers)
• fixed length modifiers for some field definitions.
Building upon the above, we can say that the modifiers alter the field definition to create
more specific field types for specific usage scenarios. The notnull modifier will be used in the
following way to set the default DBMS NOT NULL Flag on the field to true or false,
depending on the DBMS's definition of the field value: In PostgreSQL the "NOT NULL"
definition will be set to "NOT NULL", whilst in MySQL (for example) the "NULL" option will
be set to "NO". In order to define a "NOT NULL" field type, we simply add an extra parameter
to our definition array (See the examples in the following section)
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7-7
'sometime' = array(
'type' => 'time',
'default' => '12:34:05',
'notnull' => true,
),
Using the above example, we can also explore the default field operator. Default is set in the
same way as the notnull operator to set a default value for the field. This value may be set in
any character set that the DBMS supports for text fields, and any other valid data for the
field's data type. In the above example, we have specified a valid time for the "Time" data
type, '12:34:05'. Remember that when setting default dates and times, as well as datetimes,
you should research and stay within the epoch of your chosen DBMS, otherwise you will
encounter difficult to diagnose errors!
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'sometext' = array(
'type' => 'string',
'length' => 12,
),
The above example will create a character varying field of length 12 characters in the
database table. If the length definition is left out, Doctrine will create a length of the
maximum allowable length for the data type specified, which may create a problem with some
field types and indexing. Best practice is to define lengths for all or most of your fields.
Boolean
The boolean data type represents only two values that can be either 1 or 0. Do not assume
that these data types are stored as integers because some DBMS drivers may implement this
type with single character text fields for a matter of efficiency. Ternary logic is possible by
using null as the third possible value that may be assigned to fields of this type.
The next several examples are not meant for you to use and give them a try. They are
simply for demonstrating purposes to show you how to use the different Doctrine data
types using PHP code or YAML schema files.
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