Group

Data model representing a shared expense group in Divvy

The Group model represents a collection of users who share expenses together. Each group tracks its members, balance, and visual identity.

Data Class Definition

Group.kt

package com.example.divvy.models

import com.example.divvy.components.GroupIcon
import kotlinx.serialization.Serializable

@Serializable
data class Group(
    val id: String,
    val name: String,
    val emoji: String = "",
    val icon: GroupIcon = GroupIcon.Group,
    val memberCount: Int = 0,
    val balanceCents: Long = 0L,
    val currency: String = "USD",
    val createdBy: String = ""
) {
    /** Positive = you are owed, negative = you owe */
    val isOwed: Boolean get() = balanceCents >= 0

    val formattedBalance: String
        get() {
            val dollars = kotlin.math.abs(balanceCents) / 100.0
            return "$${String.format("%.2f", dollars)}"
        }

    val balanceLabel: String
        get() = if (isOwed) "You are owed ${formattedBalance}" else "You owe ${formattedBalance}"
}

Source: [Group.kt:7]

Fields

id · String · required

Unique identifier for the group

name · String · required

Display name of the group (e.g., “Roommates”, “Europe Trip”)

emoji · String · default: "\"\""

Optional emoji character to display alongside the group icon

icon · GroupIcon · default: "GroupIcon.Group"

Visual icon for the group. See [GroupIcon] for available options.

memberCount · Int · default: "0"

Number of members currently in the group

balanceCents · Long · default: "0L"

Current user’s balance in cents. Positive values indicate the user is owed money, negative values indicate the user owes money.

currency · String · default: "\"USD\""

Three-letter ISO currency code for the group’s transactions

createdBy · String · default: "\"\""

User ID of the member who created the group

Computed Properties

The Group model includes several computed properties for convenient UI display:

isOwed

val isOwed: Boolean get() = balanceCents >= 0

Returns true if the current user is owed money (balance is positive or zero), false if they owe money.

formattedBalance

val formattedBalance: String
    get() {
        val dollars = kotlin.math.abs(balanceCents) / 100.0
        return "$${String.format("%.2f", dollars)}"
    }

Returns the absolute value of the balance formatted as a dollar amount (e.g., “$15.50”).

balanceLabel

val balanceLabel: String
    get() = if (isOwed) "You are owed ${formattedBalance}" else "You owe ${formattedBalance}"

Returns a human-readable label describing the user’s balance (e.g., “You are owed $15.50" or "You owe$15.50”).

Relationships

• Members: A group contains multiple users. See GroupMember for member details.
• Expenses: A group can have many expenses. See Expense and GroupExpense models.
• Balances: Each member has a balance within the group. See MemberBalance.

Usage Examples

Creating a Group

val group = Group(
    id = "grp_123",
    name = "Roommates",
    icon = GroupIcon.Home,
    memberCount = 3,
    balanceCents = 1550L, // User is owed $15.50
    currency = "USD",
    createdBy = "user_abc"
)

Accessing Computed Properties

val group = Group(
    id = "grp_123",
    name = "Roommates",
    balanceCents = -2500L // User owes $25.00
)

println(group.isOwed)           // false
println(group.formattedBalance) // "$25.00"
println(group.balanceLabel)     // "You owe $25.00"

Repository Operations

From [GroupRepository.kt]:

// Create a new group
suspend fun createGroup(name: String, icon: GroupIcon): Group {
    val id = "grp_${UUID.randomUUID()}"
    return Group(id = id, name = name, icon = icon, createdBy = "u_me")
}

// Get a group by ID
fun getGroup(groupId: String): Flow<Group>

// Update group details
suspend fun updateGroup(groupId: String, name: String, icon: GroupIcon)

// Delete a group
suspend fun deleteGroup(groupId: String)

Serialization

The Group model uses Kotlin Serialization with the @Serializable annotation. All fields are serialized with their property names (no custom @SerialName annotations).