iartemiev
commented
1 year ago For this schema
type Post @model {
id: ID!
title: String!
comments: [Comment] @hasMany
}
type Comment @model {
id: ID!
post: Post @belongsTo
content: String!
}You can filter comments by the post instance. For example:
const post = await DataStore.query(Post, 'YOUR_POST_ID');
const comments = await DataStore.query(Comment, c => c.post.eq(post));If you want to be able to specify the foreign key specifically, try
type Post @model {
id: ID!
title: String!
comments: [Comment] @hasMany(indexName: "byPost", fields: ["id"])
}
type Comment @model {
id: ID!
postID: ID! @index(name: "byPost")
post: Post @belongsTo(fields: ["postID"])
content: String!
}Note: the @index doesn't need a sortKeyFields attribute.
Then you can you filter by postID:
const comments = await DataStore.query(Comment, c => c.postID.eq('YOUR_POST_ID'));Regarding your authorization question a couple points:
- The
groupClaimvalue would need to match the name of the custom claim in your Cognito identity token. How are you adding the custom claim and injecting values into it? Are you leveraging a pre token generation lambda trigger? - When you perform a save such as
const post = await DataStore.save(new Post({ title: "test" }));
await DataStore.save(
new Comment({
post: post,
content: "test comment",
})
);The postCommentsId in the actual mutation query that gets sent to AppSync will be automatically populated with the id field of the post. You can see this if you inspect the network requests in dev tools. This is also true for queries and subscriptions - the postCommentsId is included in the selection set.
Therefore the auth resolver in AppSync will also have access to this field if you’re using it for auth. If you enable Logs with verbose content in your AppSync API settings, you should see the postCommentsId in the resolver evaluation logs (in $ctx.args or $ctx.result for create and update/delete mutations respectively).
ritxweb
Before opening, please confirm:
JavaScript Framework
Angular
Amplify APIs
Authentication, GraphQL API
Amplify Categories
auth, api
Environment information
Describe the bug
When creating two models with a one to many relationship acording to the example on the documentation https://docs.amplify.aws/lib/datastore/relational/q/platform/js/:
It creates under the hood an attribute in the Comment model called postCommentsId where it stores the Id referencing to the Post it belongs to. It even creates a GSI with that field as primary key to make even easier to search for this attribute. This attribute can be used for instance from the query editor in the aws console for appsync, to query, sync or subscribe for Comments that belong to a Post with a particular post Id.
This is the ideal behaviour I think it should had. But the problem comes when I try to use this attribute with DataStore query or subscribe since it is not pressent on the javascript implementation that Amplify creates when generating models. In the documentation it says that you can query for the comments of a post by querying for the post and getting the comments field or directly querying for the comments with a post with that id:
But there is no option for querying directly for the Comments with a postCommentsId equal to the Post Id you want, even if this GSI actually exists. This is annoying with queries although it can be saved using the options in the documentation, but it becomes a big problem with subscriptions and authorizations. DataStore javascript classes do not allow to subscribe to fields in relationships:
This doesn't work and as the field postCommentsId does not exists in the javascript classes created, we can also not filter for that field so filter and only syncronize Comments that belong to a Post in a system with thousands of Comments becomes impossible.
It also create problems with authoization, if I use a custom claim to store the list of Posts a User has and I want to allow access to the Comments only to users that has the postCommentsId field among this Posts from the claim it doesn't work since mutations do not return this field among the attributes so the Auth resolver fails to "unauthorized".
I have tried by creating the field manually with the model:
Also creating the index like appsync says in the documentation here https://docs.amplify.aws/cli/graphql/data-modeling/#belongs-to-relationship:
But none of this works. This is a continuation of the issue #8285 that was closed and forgotten almost two years ago but I think this is very necessary.
Expected behavior
Datastore includes the foreign key Id attributes in one to many relationships in javascript generated classes so queries and subscriptions can use it.
Reproduction steps
Follow example in documentation.
Code Snippet
Log output
aws-exports.js
No response
Manual configuration
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Additional configuration
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Mobile Device
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Mobile Operating System
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Mobile Browser
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Mobile Browser Version
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Additional information and screenshots
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