What is the best way to store global state data for an application. Right now I have a State Type, and I only create one of this object which I read/update as needed. If a second was created for whatever reason it would totally break things.
I want to store the state in Slash GraphQL. Right now the State is just simply one field, but more things may be added later.
Is there a better way than just creating a type and pre-creating the initial row of it to later read/update as needed. Is there a way to enforce only having one instance of this type?
Unfortunately no. There’s no way to enforce that you have only one of an object of a given type.
However, if you want to be clever, you can write a lambda query:
type Mutation {
newState($field FIELDTYPE): ID! @lambda
}
Then add this to your resolvers (fill in the THINGSINCAPS with your actual code):
async function newState({args, graphql}) {
// check that a State doesn't already exist
const a = await dql.query(`query queryState() {
queryState(func: type(State))) {
expand(__all__)
}
}`, {})
if a.data.queryState.length == 0 {
// add new State
b = await graphql( GRAPQL_CODE_TO_ADD_NEW_STATE )
return b.data.addState.State[0].id
}
// return the old state ID
return a.data.queryState.State[0].id
}
self.addGraphQLResolvers({
"Mutation.newState": newState
})
Now dgraph provides AddState mutations. It has to be up to you to NOT use AddState but rather use newState
@gja/@pawan might have a better solution or may want to add a constraint directive into Slash (hint hint)
