Uncaught Invariant Violation: Store error

Question

I am attempting to write a HackerNews clone using a graphql api written in Go with the graph-gophers package as the backend, and a Vuejs app with the apollo graphql-client as the frontend. Relevant Github Repos Backend Frontend.

I have recently implemented subscription functionality and it does appear to work, but whenever I upvote a link I get a nasty error in the javascript console, the full text for which is below.

Observable.js?5234:65 Uncaught Invariant Violation: Store error: the application attempted to write an object with no provided id but the store already contains an id of Link:10 for this object. The selectionSet that was trying to be written is:
{"kind":"Field","name":{"kind":"Name","value":"link"},"arguments":[],"directives":[],"selectionSet":{"kind":"SelectionSet","selections":[{"kind":"Field","name":{"kind":"Name","value":"votes"},"arguments":[],"directives":[],"selectionSet":{"kind":"SelectionSet","selections":[{"kind":"Field","name":{"kind":"Name","value":"id"},"arguments":[],"directives":[]},{"kind":"Field","name":{"kind":"Name","value":"user"},"arguments":[],"directives":[],"selectionSet":{"kind":"SelectionSet","selections":[{"kind":"Field","name":{"kind":"Name","value":"id"},"arguments":[],"directives":[]},{"kind":"Field","name":{"kind":"Name","value":"__typename"}}]}},{"kind":"Field","name":{"kind":"Name","value":"__typename"}}]}},{"kind":"Field","name":{"kind":"Name","value":"__typename"}}]}}
    at new InvariantError (webpack-internal:///./node_modules/ts-invariant/lib/invariant.esm.js:16:28)
    at invariant (webpack-internal:///./node_modules/ts-invariant/lib/invariant.esm.js:28:15)
    at StoreWriter.writeFieldToStore (webpack-internal:///./node_modules/apollo-cache-inmemory/lib/bundle.esm.js:680:166)
    at eval (webpack-internal:///./node_modules/apollo-cache-inmemory/lib/bundle.esm.js:576:27)
    at Array.forEach (<anonymous>)
    at StoreWriter.writeSelectionSetToStore (webpack-internal:///./node_modules/apollo-cache-inmemory/lib/bundle.esm.js:567:33)
    at StoreWriter.writeFieldToStore (webpack-internal:///./node_modules/apollo-cache-inmemory/lib/bundle.esm.js:665:22)
    at eval (webpack-internal:///./node_modules/apollo-cache-inmemory/lib/bundle.esm.js:576:27)
    at Array.forEach (<anonymous>)
    at StoreWriter.writeSelectionSetToStore (webpack-internal:///./node_modules/apollo-cache-inmemory/lib/bundle.esm.js:567:33)
WriteError @ bundle.esm.js?d5b7:498
enhanceErrorWithDocument @ bundle.esm.js?d5b7:505
StoreWriter.writeResultToStore @ bundle.esm.js?d5b7:544
InMemoryCache.write @ bundle.esm.js?d5b7:875
eval @ bundle.esm.js?6445:1867
eval @ bundle.esm.js?6445:1867
InMemoryCache.performTransaction @ bundle.esm.js?d5b7:943
DataStore.markMutationResult @ bundle.esm.js?6445:1866
next @ bundle.esm.js?6445:1011
notifySubscription @ Observable.js?5234:135
onNotify @ Observable.js?5234:179
next @ Observable.js?5234:235
eval @ bundle.esm.js?6445:866
next @ bundle.esm.js?6445:866
notifySubscription @ Observable.js?5234:135
onNotify @ Observable.js?5234:179
next @ Observable.js?5234:235
eval @ bundle.esm.js?8322:76
setTimeout (async)
hostReportError @ Observable.js?5234:64
notifySubscription @ Observable.js?5234:149
onNotify @ Observable.js?5234:179
next @ Observable.js?5234:235
eval @ bundle.esm.js?6445:866
next @ bundle.esm.js?6445:866
notifySubscription @ Observable.js?5234:135
onNotify @ Observable.js?5234:179
next @ Observable.js?5234:235
eval @ bundle.esm.js?8322:76
Promise.then (async)
eval @ bundle.esm.js?8322:75
Subscription @ Observable.js?5234:197
subscribe @ Observable.js?5234:279
eval @ bundle.esm.js?6445:864
Subscription @ Observable.js?5234:197
subscribe @ Observable.js?5234:279
eval @ bundle.esm.js?6445:1001
eval @ bundle.esm.js?6445:998
step @ tslib.es6.js?4d3a:100
eval @ tslib.es6.js?4d3a:81
eval @ tslib.es6.js?4d3a:74
__awaiter @ tslib.es6.js?4d3a:70
QueryManager.mutate @ bundle.esm.js?6445:950
ApolloClient.mutate @ bundle.esm.js?6445:2016
mutate @ vue-apollo.esm.js?ebd5:1286
voteForLink @ LinkItem.vue?5bee:46
click @ LinkItem.vue?441e:18
invokeWithErrorHandling @ vue.esm.js?efeb:1863
invoker @ vue.esm.js?efeb:2188
original._wrapper @ vue.esm.js?efeb:7565

I've done enough debugging to confirm that nothing I'm trying to add to the store is missing any ids. I'm not sure what I'm missing here that is causing this error. Everything seems to work but I'd like to know why this error keeps getting thrown.

Answer 1

I ended up figuring this out. The cause of the error was when updating the store when an upvote occurred, I had been focusing on the vote subscription in the graphql schema, when the issue was actually in the upvote mutation. The link returned as part of the schema was missing an id.