use a pre put hook to do your checking:
class Fruit(ndb.Model):
name = ndb.StringProperty(required=True)
color = ndb.StringProperty(required=True)
taste = ndb.StringProperty(required=True)
def _pre_put_hook(self):
On Thursday, January 19, 2017 at 5:39:56 AM UTC+2, Ryan Ang Wei En wrote:
>
> I have this sample json of a list of "Fruit":
> {
> "apple":{
> "color":red"
> "taste":"sweet"
> }
> "pineapple":{
> "color":yellow"
> "taste":"sour"
> }
> }
> I want to use a very object oriented approach to retrieve a property of my
> entity using a string key.
> The requirements:
> 1) NDB must not be able to store any "Fruit" without the "color" or
> "taste" fields. (JsonProperty does not meet this requirement)
> 2) "apple" and "pineapple" are unique identifiers, used to retrieve it's
> corresponding fruit data, NDB must not be able to store multiple fruit
> objects containing the same unique identifier.
>
> class Fruit(ndb.Model):
> name = ndb.StringProperty(required=True)
> color = ndb.StringProperty(required=True)
> taste = ndb.StringProperty(required=True)
>
> class Person(ndb.Model):
> favoritefruits = ndb.StructuredProperty(required=True,repeated=true)
>
> Then to find apple,
> person = Person.get_by_id("Johnathan").favouritefruits
> for fruit in person.favoritefruits:
> if fruit.name == "apple"
> # found apple!
>
> The problem:
> Multiple "Fruit" objects containing the same "name" property can exist in
> the "favoritefruits" property.
>
> What solutions are there that will fulfil both requirements 1) and 2)?
>
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