How to reply to a message via Community Api V2

Hi UpakulB 
Try this one

community.MyCommunity.com/restapi/vc/messages/id/5595/reply?message.body=Go

Here is the documentation
https://community.lithium.com/t5/Developer-Knowledge-Base/Replying-to-a-post-via-Community-API/ta-p/8569
You can send the additional parameter as well see here

UpakulB - subject* and board* parameter are required for posting a new message using API V2. However, you are missing the board* parameter, which is required as shown here https://community.lithium.com/t5/Developer-Documentation/bd-p/dev-doc-portal?section=commv2&collection=messages#action-create-attachments. 

Let me know if this worked for you or if you still can't find the message, could you please post the response of your message. 

TariqHussain, thanks for your message

As suggested I added the board Id in the Body

{
"data": {
"type": "message",
"subject": "hello world",
"body": "this is a message post.",
"parent" : "105",
"board": {
"id" : "health_and_fitness_club"
}}}

Got below Response, but still replies are not showing

{
"status": "success",
"message": "",
"http_code": 200,
"data": {
"type": "message",
"id": "105",
"href": "/messages/105",
"view_href": "http://community.infogain.com:80/t5/Health-and-fitness-club/Carrom-Tournament-Successful-completion/m-p/105#M2",
"author": {
"type": "user",
"id": "1051",
"href": "/users/1051",
"view_href": "http://community.infogain.com:80/t5/user/viewprofilepage/user-id/1051",
"login": "Mohit_I"
},
"subject": "hello world",
"body": "this is a message post.",
"teaser": "",
"board": {
"type": "board",
"id": "health_and_fitness_club",
"href": "/boards/health_and_fitness_club",
"view_href": "http://community.infogain.com:80/t5/Health-and-fitness-club/bd-p/health_and_fitness_club"
},
"conversation": {
"type": "conversation",
"id": "105",
"view_href": "http://community.infogain.com:80/t5/Health-and-fitness-club/Carrom-Tournament-Successful-completion/td-p/105",
"style": "forum",
"thread_style": "forum",
"messages_count": 1,
"solved": false,
"last_post_time": "2017-07-13T04:13:34.547-07:00",
"last_post_time_friendly": "2 weeks ago"
},
"topic": {
"type": "message",
"id": "105",
"href": "/messages/105",
"view_href": "http://community.infogain.com:80/t5/Health-and-fitness-club/Carrom-Tournament-Successful-completion/m-p/105#M2"
},
"post_time": "2017-07-13T04:13:34.547-07:00",
"post_time_friendly": "2 weeks ago",
"depth": 0,
"read_only": false,
"language": "EN",
"can_accept_solution": false,
"placeholder": false,
"is_solution": false,
"solution_data": {},
"metrics": {
"type": "message_metrics",
"views": 23
},
"current_revision": {
"type": "revision",
"last_edit_author": {
"type": "user",
"id": "1051",
"href": "/users/1051",
"view_href": "http://community.infogain.com:80/t5/user/viewprofilepage/user-id/1051",
"login": "Mohit_I"
},
"last_edit_time": "2017-07-13T04:13:34.547-07:00"
},
"kudos": {
"query": "SELECT * FROM kudos WHERE message.id = '105'"
},
"tags": {
"query": "SELECT * FROM tags WHERE messages.id = '105'"
},
"labels": {
"query": "SELECT * FROM labels WHERE messages.id = '105'"
},
"images": {
"query": "SELECT * FROM images WHERE messages.id = '105'"
},
"videos": {
"query": "SELECT * FROM videos WHERE messages.id = '105'"
},
"attachments": {
"query": "SELECT * FROM attachments WHERE message.id = '105'"
},
"replies": {
"query": "SELECT * FROM messages WHERE parent.id = '105'"
},
"ratings": {
"query": "SELECT * FROM ratings WHERE message.id = '105'"
},
"custom_tags": {
"query": "SELECT * FROM custom_tags WHERE messages.id = '105'"
},
"moderation_status": "approved",
"user_context": {
"type": "user_context",
"kudo": false,
"read": true,
"can_reply": true,
"can_kudo": true,
"can_delete": true
},
"device_id": "google_chrome_59",
"popularity": -342.51438194444444,
"excluded_from_kudos_leaderboards": false
},
"metadata": {}
}

UpakulB - Have you tried this URL http://community.infogain.com/t5/Health-and-fitness-club/Carrom-Tournament-Successful-completion/m-p/105#M2? I don't have access to check this page. But I believe, this message has been added already. 

You can check this message using the following query.

SELECT * FROM messages WHERE id = '105'

TariqHussain - This (id = 105) is the parent message and its visible but I need to post the reply and there is no reply added on this message yet.

UpakulB - Could you please use parent.id instead of a parent only. 

When using parent.id getting below error-

{
"status": "error",
"message": "Unable to parse the required Content-Body from the request.",
"data": {
"type": "error_data",
"code": 308,
"developer_message": "Unrecognized field \"parent.id\" (class lithium.api.lion.impl.StandardComplexObjectDefinition), not marked as ignorable",
"more_info": ""
},
"metadata": {}
}

UpakulB - For posting a reply using v2 parent param is being used. Could you please open a case with lithium support as your query seems to be right and you are getting the proper response.  

I assume you have used all the required parameters mentioned in the doc. 

POST /community/2.0/mytenantid/messages HTTP/1.1
Host: api.lithium.com
Content-Type: application/json
Cache-Control: no-cache
client-id: czY8mbW76Ac/Wz6+bAMhCm+sW5WSyhAO2odh28TB1/c=