DEF-VIEW-CLASS — Defines CLOS classes with mapping to SQL database.Macro
nameThe class name.
superclassesThe superclasses for the defined class.
slotsThe class slot definitions.
class optionsThe class options.
classThe defined class.
	    :db-kind - specifies the kind of
	    database mapping which is performed for this slot and
	    defaults to :base which indicates
	    that the slot maps to an ordinary column of the database
	    table. A :db-kind value of
	    :key indicates that this slot is a
	    special kind of :base slot which
	    maps onto a column which is one of the unique keys for the
	    database table, the value :join
	    indicates this slot represents a join onto another
	    View Class
	    which contains View Class objects, and the value
	    :virtual indicates a standard CLOS
	    slot which does not map onto columns of the database
	    table.
	  
	    :db-info - if a slot is specified
	    with :db-kind
	    :join, the slot option
	    :db-info contains a property list
	    which specifies the nature of the join. The valid members
	    of the list are:
	  
		:join-class
		class-name - the name of the
		class to join on.
	      
		:home-key
		slot-name - the name of the slot
		of this class for joining
	      
		:foreign-key
		slot-name - the name of the slot
		of the :join-class for joining
	      
		:target-slot
		target-slot - this is an optional
		parameter. If specified, then the join slot of the
		defining class will contain instances of this target
		slot rather than of the join class. This can be useful
		when the :join-class is an
		intermediate class in a
		many-to-many relationship and the
		application is actually interested in the
		:target-slot.
	      
		:retrieval
		time - The default value is
		:deferred, which defers filling
		this slot until the value is accessed. The other valid
		value is :immediate which
		performs the SQL query when the instance of the class
		is created. In this case, the
		:set is automatically set to
		NIL
	      
		:set set -
		This controls what is stored in the join slot.  The
		default value is T. When set is
		T and target-slot is undefined,
		the join slot will contain a list of instances of the
		join class. Whereas, if
		target-slot is defined, then the
		join slot will contain a list of pairs of
		(target-value join-instance).
		When set is NIL, the join slot
		will contain a single instances.
	      
	    :type - for slots of
	    :db-kind :base or
	    :key, the :type slot
	    option has a special interpretation such that Lisp
	    types, such as string, integer and float are
	    automatically converted into appropriate SQL types for
	    the column onto which the slot maps. This behaviour may
	    be overridden using the :db-type slot
	    option. The valid values are:
	    
| string- a variable length
		character field up to *default-string-length*
		characters. | 
| (string n)- a fixed length
		character fieldncharacters
		long. | 
| varchar- a variable length
		character field up to *default-string-length*
		characters. | 
| (varchar n)- a variable length
		character field up toncharacters in length. | 
| char- a single character field | 
| integer- signed integer
	      at least 32-bits wide | 
| (integer n) | 
| float | 
| (float n) | 
| long-float | 
| number | 
| (number n) | 
| (number n p) | 
| tinyint- An integer column 8-bits
		wide. [not supported by all database backends] | 
| smallint- An integer column 16-bits
		wide. [not supported by all database backends] | 
| bigint- An integer column
		64-bits wide. [not supported by all database backends] | 
| universal-time- an integer
		field sufficiently wide to store a
		universal-time. On most databases, a slot of this
		type assigned a SQL type ofBIGINT | 
| wall-time- a slot which stores
		a date and time in a SQL timestamp column. CLSQL
		provides a number of time manipulation functions to
		support objects of type wall-time. | 
| date- a slot which stores the
		date (without any time of day resolution) in a
                column. CLSQL provides a number of time
		manipulation functions that operate on date values. | 
| duration- stores a
		duration structure.  CLSQL provides
		routines for wall-time and
		duration processing. | 
| boolean- stores aTorNILvalue. | 
| generalized-boolean- similar
		to abooleanin that either aTorNILvalue is stored in the SQL
		database. However, any Lisp object can be stored in
		the Lisp object. A Lisp value ofNILis stored asFALSEin the database, any
		other Lisp value is stored asTRUE. | 
| keyword- stores a keyword | 
| symbol- stores a symbol | 
| list- stores a list by writing
		it to a string. The items in the list must be able to
		be readable written. | 
| vector- stores a vector
	      similarly tolist | 
| array- stores a array
	      similarly tolist | 
	    :column - specifies the name of
	    the SQL column which the slot maps onto, if
	    :db-kind is not
	    :virtual, and defaults to the
	    slot name. If the slot name is used for the SQL column
	    name, any hypens in the slot name are converted
	    to underscore characters.
	  
	    :void-value - specifies the value
	    to store in the Lisp instance if the SQL value is NULL and
	    defaults to NIL.
	  
	    :db-constraints - is a keyword
	    symbol representing an SQL column constraint expression or
	    a list of such symbols. The following column constraints
	    are supported: :not-null,
	    :primary-key, :unique,
	    :unsigned (MySQL specific),
	    :zerofill (MySQL specific) and
	    :auto-increment (MySQL specific).
	  
	    :db-type - a string to specify the SQL
	    column type. If specified, this string overrides the SQL
	    column type as computed from the :type
	    slot value.
	  
	    :db-reader - If a string, then when
	    reading values from the database, the string will be used
	    for a format string, with the only value being the value
	    from the database.  The resulting string will be used as
	    the slot value.  If a function then it will take one
	    argument, the value from the database, and return the
	    value that should be put into the slot. If a symbol, then
	    the symbol-function of the symbol will be used.
          
	    :db-writer - If a string, then when
	    reading values from the slot for the database, the string
	    will be used for a format string, with the only value
	    being the value of the slot.  The resulting string will be
	    used as the column value in the database.  If a function
	    then it will take one argument, the value of the slot, and
	    return the value that should be put into the database. If
	    a symbol, then the symbol-function of the symbol will be
	    used.
          
	      :base-table - specifies the name
	      of the SQL database table. The default value is the
	      class name. Like slot names, hypens in the class name
	      are converted to underscore characters.
	    
	      :normalizedp - specifies whether
          this class uses normalized inheritance from parent classes.
          Defaults to nil, i.e. non-normalized schemas. When true,
          SQL database tables that map to this class and parent
          classes are joined on their primary keys to get the full
          set of database columns for this class.
	    
	Creates a View
	Class called name whose
	slots slots can map onto the attributes
	of a table in a database. If
	superclasses is NIL then the
	superclass of class will be
	standard-db-object, otherwise
	superclasses is a list of superclasses
	for class which must include
	standard-db-object or a descendent of
	this class.
      
Specifying that :normalizedp is T tells CLSQL to normalize the database schema for inheritance. What this means is shown in the examples below.
With :normalizedp equal to NIL (the default) the class inheritance would result in the following:
(def-view-class node ()
  ((title :accessor title :initarg :title :type (varchar 240))))
SQL table NODE:
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| TITLE | varchar(240) | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
(def-view-class user (node)
  ((user-id :accessor user-id :initarg :user-id
            :type integer :db-kind :key :db-constraints (:not-null))
   (nick :accessor nick :initarg :nick :type (varchar 64))))
SQL table USER:
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| USER_ID | int(11)      | NO   | PRI |         |       |
| NICK    | varchar(64)  | YES  |     | NULL    |       |
| TITLE   | varchar(240) | YES  |     | NULL    |       |
+---------+--------------+------+-----+---------+-------+
      Using :normalizedp T, both view-classes need a primary key to join them on:
(def-view-class node ()
  ((node-id :accessor node-id :initarg :node-id
            :type integer :db-kind :key
            :db-constraints (:not-null))
   (title :accessor title :initarg :title :type (varchar 240))))
SQL table NODE:
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| NODE_ID | int(11)      | NO   | PRI |         |       |
| TITLE   | varchar(240) | YES  |     | NULL    |       |
+---------+--------------+------+-----+---------+-------+
(def-view-class user (node)
  ((user-id :accessor user-id :initarg :user-id
            :type integer :db-kind :key :db-constraints (:not-null))
   (nick :accessor nick :initarg :nick :type (varchar 64)))
  (:normalizedp t))
SQL table USER:
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| USER_ID | int(11)     | NO   | PRI |         |       |
| NICK    | varchar(64) | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+
      In this second case, all slots of the view-class 'node are also available in view-class 'user, and can be used as one would expect. For example, with the above normalized view-classes 'node and 'user, and SQL tracing turned on:
CLSQL> (setq test-user (make-instance 'user :node-id 1 :nick "test-user"
                                            :title "This is a test user"))
#<USER {1003B392E1}>
CLSQL> (update-records-from-instance test-user :database db)
;; .. => INSERT INTO NODE (NODE_ID,TITLE) VALUES (1,'This is a test user')
;; .. <= T
;; .. => INSERT INTO USER (USER_ID,NICK) VALUES (1,'test-user')
;; .. <= T
1
CLSQL> (node-id test-user)
1
CLSQL> (title test-user)
"This is a test user"
CLSQL> (nick test-user)
"test-user"
      Notes from a refactor of this code. There are many assumptions that need to be met for normalized classes to work * The each of the classes should have its own single key column (of a different name) that will contain an identical value. EG: node has a node-id, setting which is a node has a node-id and a setting-id which must be equal. You cannot use node-id as the primary key on both tables (as I would have expected). The exception to this seems to be if your class has no slots at all, then you dont need to have a single key column, because your class is fully represented in the db by its parent(s) * more than one parent class per normalized class should be considered experimental and untested (vaya con Dios) * There are a few code paths that just dont pay any attention to normalized classes eg: delete-records-for-instance
The following examples are from the CLSQL test suite.
(def-view-class person (thing)
  ((height :db-kind :base :accessor height :type float
           :initarg :height)
   (married :db-kind :base :accessor married :type boolean
            :initarg :married)
   (birthday :type clsql:wall-time :initarg :birthday)
   (bd-utime :type clsql:universal-time :initarg :bd-utime)
   (hobby :db-kind :virtual :initarg :hobby :initform nil)))
(def-view-class employee (person)
  ((emplid
    :db-kind :key
    :db-constraints :not-null
    :type integer
    :initarg :emplid)
   (groupid
    :db-kind :key
    :db-constraints :not-null
    :type integer
    :initarg :groupid)
   (first-name
    :accessor first-name
    :type (varchar 30)
    :initarg :first-name)
   (last-name
    :accessor last-name
    :type (varchar 30)
    :initarg :last-name)
   (email
    :accessor employee-email
    :type (varchar 100)
    :initarg :email)
   (ecompanyid
    :type integer
    :initarg :companyid)
   (company
    :accessor employee-company
    :db-kind :join
    :db-info (:join-class company
			  :home-key ecompanyid
			  :foreign-key companyid
			  :set nil))
   (managerid
    :type integer
    :initarg :managerid)
   (manager
    :accessor employee-manager
    :db-kind :join
    :db-info (:join-class employee
			  :home-key managerid
			  :foreign-key emplid
			  :set nil))
   (addresses
    :accessor employee-addresses
    :db-kind :join
    :db-info (:join-class employee-address
			  :home-key emplid
			  :foreign-key aemplid
			  :target-slot address
			  :set t)))
  (:base-table employee))
(def-view-class company ()
  ((companyid
    :db-kind :key
    :db-constraints :not-null
    :type integer
    :initarg :companyid)
   (groupid
    :db-kind :key
    :db-constraints :not-null
    :type integer
    :initarg :groupid)
   (name
    :type (varchar 100)
    :initarg :name)
   (presidentid
    :type integer
    :initarg :presidentid)
   (president
    :reader president
    :db-kind :join
    :db-info (:join-class employee
			  :home-key presidentid
			  :foreign-key emplid
			  :set nil))
   (employees
    :reader company-employees
    :db-kind :join
    :db-info (:join-class employee
			  :home-key (companyid groupid)
			  :foreign-key (ecompanyid groupid)
			  :set t))))
(def-view-class address ()
  ((addressid
    :db-kind :key
    :db-constraints :not-null
    :type integer
    :initarg :addressid)
   (street-number
    :type integer
    :initarg :street-number)
   (street-name
    :type (varchar 30)
    :void-value ""
    :initarg :street-name)
   (city
    :column "city_field"
    :void-value "no city"
    :type (varchar 30)
    :initarg :city)
   (postal-code
    :column zip
    :type integer
    :void-value 0
    :initarg :postal-code))
  (:base-table addr))
;; many employees can reside at many addressess
(def-view-class employee-address ()
  ((aemplid :type integer :initarg :emplid)
   (aaddressid :type integer :initarg :addressid)
   (verified :type boolean :initarg :verified)
   (address :db-kind :join
	    :db-info (:join-class address
				  :home-key aaddressid
				  :foreign-key addressid
				  :retrieval :immediate)))
  (:base-table "ea_join"))
(def-view-class deferred-employee-address ()
  ((aemplid :type integer :initarg :emplid)
   (aaddressid :type integer :initarg :addressid)
   (verified :type boolean :initarg :verified)
   (address :db-kind :join
	    :db-info (:join-class address
				  :home-key aaddressid
				  :foreign-key addressid
				  :retrieval :deferred
				  :set nil)))
  (:base-table "ea_join"))
      
	The actual SQL type for a column depends up the database type
	in which the SQL table is stored. As an example, the view
	class type (varchar 100) specifies a
	SQL column type VARCHAR(100) in MySQL
	and a column type VARCHAR2(100) in
	Oracle
      
	The actual lisp type for a slot may be different than the
	value specified by the :type attribute.
	For example, a slot declared with ":type (string
	30)" actually sets the slots Lisp type as
	(or null string). This is to allow a
	NIL value or a string shorter than 30 characters to be
	stored in the slot.