I'm not sure how to model basic Twitter with SwiftData, at the beginning I even went to an SQL-like approach with no relationships and a bunch of pivots (which will work, but there is no point in using SwiftData in this case), but decided to try @Relationships and now I'm getting an error from the topic's title. It's more like a beg for help rather than a question, I'd like to understand how to properly model smth like this using SwiftData 🫠:

import SwiftData
import LocalExtensions

@Model
public final class TweetModel: Equatable, Identifiable, Sendable {
    @Attribute(.unique)
    public var id: String
    public var createdAt: Date

    @Relationship(inverse: \UserModel.likedTweets)
    public var author: UserModel

    @Relationship
    public var repostSource: TweetModel?

    @Relationship
    public var replySource: TweetModel?

    @Relationship(inverse: \TweetModel.replySource)
    public var replies: [TweetModel]

    @Relationship(inverse: \TweetModel.repostSource)
    public var reposts: [TweetModel]

    @Relationship(inverse: \UserModel.likedTweets)
    public var likes: [UserModel]

    public var content: String

    public init(
        id: USID,
        createdAt: Date = .now,
        author: UserModel,
        repostSource: TweetModel? = nil,
        replySource: TweetModel? = nil,
        replies: [TweetModel] = [],
        reposts: [TweetModel] = [],
        likes: [UserModel] = [],
        content: String
    ) {
        self.id = id.rawValue
        self.createdAt = createdAt
        self.author = author
        self.repostSource = repostSource
        self.replySource = replySource
        self.replies = replies
        self.reposts = reposts
        self.likes = likes
        self.content = content
    }
}

import SwiftData
import LocalExtensions

@Model
public final class UserModel: Equatable, Identifiable, Sendable {
    @Attribute(.unique)
    public var id: String

    @Attribute(.unique)
    public var username: String

    public var password: Data
    public var displayName: String
    public var bio: String
    public var avatarURL: URL?

    @Relationship(deleteRule: .cascade)
    public var tweets: [TweetModel]

    @Relationship
    public var likedTweets: [TweetModel]

    @Relationship(inverse: \UserModel.followers)
    public var follows: [UserModel]

    @Relationship
    public var followers: [UserModel]

    public init(
        id: USID,
        username: String,
        password: Data,
        displayName: String = "",
        bio: String = "",
        avatarURL: URL? = nil,
        tweets: [TweetModel] = [],
        likedTweets: [TweetModel] = [],
        follows: [UserModel] = [],
        followers: [UserModel] = []
    ) {
        self.id = id.rawValue
        self.username = username
        self.password = password
        self.displayName = displayName
        self.bio = bio
        self.avatarURL = avatarURL
        self.tweets = tweets
        self.likedTweets = likedTweets
        self.follows = follows
        self.followers = followers
    }
}

Here is a project you can clone and run to get improper model with nonsensical relationship definitions crash 🌚

Well, after writing this post I noticed that I was trying to connect TweetModel.author with UserModel.likedTweets instead of UserModel.tweets