Overview
Mutations allow you to modify data in the RealtimeChat system. All message mutations automatically trigger real-time updates to subscribed clients.
All mutations automatically publish events to the MessageUpdated subscription topic, enabling real-time updates for connected clients.
SendMessage
Send a new message to a chat room. This mutation creates a message and broadcasts an ADDED event to all subscribers.
Parameters
The ID of the chat room to send the message to
The identifier of the user sending the message
The text content of the message
Return Type
MessageGraph! - The newly created message object
GraphQL Schema
type Mutation {
sendMessage(
chatRoomId: Int!
senderId: String!
text: String!
): MessageGraph!
}
type MessageGraph {
id: Int!
sentAt: DateTime!
senderId: String!
chatRoomId: Int!
content: MessageContent!
}
Example Mutation
mutation SendMessage {
sendMessage(
chatRoomId: 1
senderId: "user123"
text: "Hello, everyone!"
) {
id
sentAt
senderId
chatRoomId
content {
... on TextMessageContentGraph {
text
}
}
}
}
Example Response
{
"data": {
"sendMessage": {
"id": 104,
"sentAt": "2026-03-05T10:45:00Z",
"senderId": "user123",
"chatRoomId": 1,
"content": {
"text": "Hello, everyone!"
}
}
}
}
Real-Time Event
After execution, this mutation publishes an event to subscribers:
{
"eventType": "ADDED",
"message": {
"id": 104,
"sentAt": "2026-03-05T10:45:00Z",
"senderId": "user123",
"chatRoomId": 1,
"content": {
"text": "Hello, everyone!"
}
}
}
Implementation Details
From MessageMutation.cs:11-29:
public async Task<MessageGraph> SendMessage(
[Service] IMessageRepository messageRepository,
int chatRoomId,
string senderId,
string text)
{
var message = await messageRepository.AddAsync(new Message
{
SenderId = senderId,
ChatRoomId = chatRoomId,
Content = new TextMessageContent(text)
});
var messageGraph = mapper.Map<MessageGraph>(message);
await eventSender.SendAsync("MessageUpdated", new MessageUpdatedEvent
{
EventType = "ADDED",
Message = messageGraph
});
return messageGraph;
}
EditMessage
Update the content of an existing message. This mutation broadcasts an UPDATED event to all subscribers.
Parameters
The ID of the message to edit
The new text content for the message
Return Type
MessageGraph! - The updated message object
GraphQL Schema
type Mutation {
editMessage(
messageId: Int!
newText: String!
): MessageGraph!
}
Example Mutation
mutation EditMessage {
editMessage(
messageId: 104
newText: "Hello, everyone! (edited)"
) {
id
sentAt
senderId
chatRoomId
content {
... on TextMessageContentGraph {
text
}
}
}
}
Example Response
{
"data": {
"editMessage": {
"id": 104,
"sentAt": "2026-03-05T10:45:00Z",
"senderId": "user123",
"chatRoomId": 1,
"content": {
"text": "Hello, everyone! (edited)"
}
}
}
}
Real-Time Event
After execution, this mutation publishes an event:
{
"eventType": "UPDATED",
"message": {
"id": 104,
"sentAt": "2026-03-05T10:45:00Z",
"senderId": "user123",
"chatRoomId": 1,
"content": {
"text": "Hello, everyone! (edited)"
}
}
}
Implementation Details
From MessageMutation.cs:31-44:
public async Task<MessageGraph> EditMessage(
[Service] IMessageRepository messageRepository,
int messageId,
string newText)
{
var message = await messageRepository.UpdateContentAsync(
messageId,
new TextMessageContent(newText)
);
var messageGraph = mapper.Map<MessageGraph>(message);
await eventSender.SendAsync("MessageUpdated", new MessageUpdatedEvent
{
EventType = "UPDATED",
Message = messageGraph
});
return messageGraph;
}
The sentAt timestamp is not modified when editing a message.
DeleteMessage
Delete a message from a chat room. This mutation broadcasts a DELETED event to all subscribers.
Parameters
The ID of the message to delete
Return Type
MessageGraph! - The deleted message object (before deletion)
GraphQL Schema
type Mutation {
deleteMessage(messageId: Int!): MessageGraph!
}
Example Mutation
mutation DeleteMessage {
deleteMessage(messageId: 104) {
id
senderId
chatRoomId
content {
... on TextMessageContentGraph {
text
}
}
}
}
Example Response
{
"data": {
"deleteMessage": {
"id": 104,
"senderId": "user123",
"chatRoomId": 1,
"content": {
"text": "Hello, everyone! (edited)"
}
}
}
}
Real-Time Event
After execution, this mutation publishes an event:
{
"eventType": "DELETED",
"message": {
"id": 104,
"senderId": "user123",
"chatRoomId": 1,
"content": {
"text": "Hello, everyone! (edited)"
}
}
}
Implementation Details
From MessageMutation.cs:46-58:
public async Task<MessageGraph> DeleteMessage(
[Service] IMessageRepository messageRepository,
int messageId)
{
var message = await messageRepository.DeleteAsync(messageId);
var messageGraph = mapper.Map<MessageGraph>(message);
await eventSender.SendAsync("MessageUpdated", new MessageUpdatedEvent
{
EventType = "DELETED",
Message = messageGraph
});
return messageGraph;
}
The mutation returns the message data before deletion, allowing clients to display what was deleted or implement undo functionality.
Complete Mutation Example
Here’s a complete example demonstrating all three mutations in sequence:
# 1. Send a new message
mutation {
sendMessage(
chatRoomId: 1
senderId: "user123"
text: "Initial message"
) {
id
content {
... on TextMessageContentGraph {
text
}
}
}
}
# 2. Edit the message
mutation {
editMessage(
messageId: 104
newText: "Updated message"
) {
id
content {
... on TextMessageContentGraph {
text
}
}
}
}
# 3. Delete the message
mutation {
deleteMessage(messageId: 104) {
id
}
}
Error Handling
Mutations may return errors in the following scenarios:
When trying to edit or delete a non-existent message
When sending a message to a non-existent chat room
When required parameters are missing or invalid
{
"errors": [
{
"message": "Sequence contains no elements",
"path": ["editMessage"],
"extensions": {
"code": "ENTITY_NOT_FOUND"
}
}
],
"data": null
}
Source Code Reference
The mutations are implemented in:
Infrastructure/RealtimeChat.Infrastructure.GraphQL/Mutations/MessageMutation.cs
Related types:
Infrastructure/RealtimeChat.Infrastructure.GraphQL/Models/MessageGraph.csInfrastructure/RealtimeChat.Infrastructure.GraphQL/Events/MessageUpdatedEvent.cs
Next Steps
Subscriptions
Learn how to subscribe to real-time message updates triggered by these mutations