Changes between Initial Version and Version 1 of S3/S3ReusableField

Timestamp:

12/01/10 20:59:32 (15 years ago)

Author:

Dominic König

Comment:

--

S3/S3ReusableField

@@ +1 @@
+[[TOC]]
+= S3ReusableField =
+
+S3ReusableField is a DRY helper class to pre-define fields in tables.
+
+== Define a S3ReusableField ==
+
+An S3ReusableField is defined like a normal [http://web2py.com/book/default/chapter/06?search=Field#DAL,-Table,-Field Field] (though outside Table definition):
+
+{{{
+person_id = S3ReusableField("person_id", db.pr_person,
+                            sortby = ["first_name", "middle_name", "last_name"],
+                            requires = IS_NULL_OR(IS_ONE_OF(db, "pr_person.id",
+                                                            shn_pr_person_represent,
+                                                            orderby="pr_person.first_name",
+                                                            sort=True,
+                                                            error_message="Person must be specified!")),
+                            represent = lambda id: (id and \
+                                        [shn_pr_person_represent(id)] or [NONE])[0],
+                            label = T("Person"),
+                            comment = shn_person_id_comment,
+                            ondelete = "RESTRICT",
+                            widget = S3PersonAutocompleteWidget(request))
+}}}
+
+This definition does '''not''' create a Field instance, it just holds the parameters.
+
+== Use S3ReusableFields in Table Definitions ==
+
+To use this in a Table definition, just call the S3ReusableField instance object to generate a Field instance:
+
+{{{
+resourcename = "mytable"
+tablename = "%s_%s" % (module, resourcename)
+table = db.define_table(tablename,
+                        ...,
+                        person_id(), # inserts a Field("person_id") with the pre-defined parameters
+                        ...,
+                        migrate=migrate)
+}}}
+
+== Override Field Attributes ==
+
+You can override the field name and any of the field attributes in the S3ReusableField when generating the Field instance, by just re-specifying them:
+
+{{{
+resourcename = "mytable"
+tablename = "%s_%s" % (module, resourcename)
+table = db.define_table(tablename,
+                        ...,
+                        person_id("reporter"), # inserts a Field("reporter") with the attributes from person_id
+                        ...,
+                        migrate=migrate)
+}}}
+
+== Deactivate IS_NULL_OR/IS_EMPTY_OR ==
+
+To deactivate a IS_NULL_OR/IS_EMPTY_OR validator in the S3ReusableField when generating the Field instance, you can use the special attribute {{{empty}}}:
+
+{{{
+resourcename = "mytable"
+tablename = "%s_%s" % (module, resourcename)
+table = db.define_table(tablename,
+                        ...,
+                        person_id(empty=False), # inserts the person_id Field, but removes IS_NULL_OR from .requires
+                        ...,
+                        migrate=migrate)
+}}}
+
+----
+DeveloperGuidelines