The ValidatorConverters are one of the really neat ideas from FunFormKit (though I use
dalchemys FormKit)
I found myself wanting to do some additional Validation of Query Strings and Session
values and I wanted to re-use the ValidatorConverters that I had.
The code I'm going to present isn't pretty, maybe someone has done this better already
and if so I'd prefer to use that but its a *technique* I think has some value even if
my coding is under-par.
Even a simple webpage might take a query-string value like 'id'. You need to do
several tests :
1. Make sure the query string contains "id".
2. Make sure "id" is numeric and if not, try to convert it.
3. Make sure "id" is in range.
4. If any of the above fail, redirect somewhere to say "Nice try buddy"
5. Put "id" somewhere useful so you don't have to refer to it as
self.request.field('id') - maybe self.id would be nice?
The following technique allows a page to register a set of Session and QueryString
validators - perhaps inheriting some from its parent.
somepage.py :
from MyWeb.Code.Templates.SitePage import SitePage
from MyWeb.Code.Validators.PageStateChecks import SessionValidatorConverter,
QueryValidatorConverter
from FormKit.Validators import MaxLength, NotEmpty, ConvertToInt
class somepage(SitePage):
def setupValidators(self):
SitePage.setupValidators(self)
svc = SessionValidatorConverter
self.validators.append(svc(self.session(),'userid','notloggedin.html',[NotEmpty(),MaxLength(10)]))
qvc = QueryValidatorConverter
self.validators.append(qvc(self.request(),'test','invalidparams.html',[NotEmpty(),ConvertToInt()]))
SitePage.py :
class SitePage(Page):
def __init__(self):
.....setup...
self.validators = []
def awake(self,trans):
Page.awake(self,trans)
self.processValidators()
def setupValidators(self):
"""Override in children to add Query/Session validators to self.validators"""
pass
def processValidators(self):
"""process validators for this page, add processed items as values of the page
or forward url to some other place (failure message page)"""
self.setupValidators()
for v in self.validators:
result, value = v.validate()
if result:
#add to self
self.__dict__[v.id] = value
else:
self.forward(v.url)
PageStateChecks.py :
from FormKit.BaseValidatorClasses import ValidatorConverter, InvalidField
from FormKit.BaseValidatorClasses import ValidatorConverter, InvalidField
class SessionValidatorConverter:
def __init__(self,session,id,url,validators=[]):
self._session = session
self.id = id
self._validators = validators
self.url = url
self._error = ''
def validate(self):
value = self._session.value(self.id,default=None)
result = 1
try:
for v in self._validators:
value = v._attemptConvert(value)
except InvalidField, msg:
self._error = str(msg)
value = None
result = 0
return result, value
class QueryValidatorConverter:
def __init__(self,request,id,url,validators=[]):
self._request = request
self.id = id
self._validators = validators
self.url = url
self._error = ''
def validate(self):
try:
value = self._request.field(self.id)
except KeyError:
value = None
result = 1
try:
for v in self._validators:
value = v._attemptConvert(value)
except InvalidField, msg:
self._error = str(msg)
result = 0
value = None
return result, value
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