hasura / streaming-chat-app

streaming-chat-app

Step 1: One-click deployment on Hasura Cloud

The fastest and easiest way to try Hasura out is via Hasura Cloud.

1. Click on the following button to deploy GraphQL engine on Hasura Cloud including Postgres add-on or using an existing Postgres database:

   

2. Open the Hasura console

   Click on the button "Launch console" to open the Hasura console.

Step 2: Apply migrations and metadata

Go to Run SQL in Console and execute the following:

CREATE TABLE public.channel_users (
    channel_id integer NOT NULL,
    user_id integer NOT NULL
);
CREATE TABLE public.messages (
    id integer NOT NULL,
    message text NOT NULL,
    author_id integer NOT NULL,
    channel_id integer NOT NULL
);
ALTER TABLE ONLY public.channel_users
    ADD CONSTRAINT channel_users_pkey PRIMARY KEY (channel_id, user_id);
ALTER TABLE ONLY public.messages
    ADD CONSTRAINT messages_pkey PRIMARY KEY (id);

Save the following in a file and then go to Import Metadata in Console:

{
  "metadata": {
    "version": 3,
    "sources": [
      {
        "name": "default",
        "kind": "postgres",
        "tables": [
          {
            "table": {
              "name": "channel_users",
              "schema": "public"
            }
          },
          {
            "table": {
              "name": "messages",
              "schema": "public"
            },
            "array_relationships": [
              {
                "name": "recipients",
                "using": {
                  "manual_configuration": {
                    "column_mapping": {
                      "channel_id": "channel_id"
                    },
                    "insertion_order": null,
                    "remote_table": {
                      "name": "channel_users",
                      "schema": "public"
                    }
                  }
                }
              }
            ],
            "select_permissions": [
              {
                "role": "user",
                "permission": {
                  "columns": [
                    "id",
                    "message",
                    "author_id",
                    "channel_id"
                  ],
                  "filter": {
                    "recipients": {
                      "user_id": {
                        "_eq": "X-Hasura-User-Id"
                      }
                    }
                  }
                }
              }
            ]
          }
        ],
        "configuration": {
          "connection_info": {
            "database_url": {
              "from_env": "PG_DATABASE_URL"
            },
            "isolation_level": "read-committed",
            "use_prepared_statements": false
          }
        }
      }
    ]
  }
}

Step 3: Try streaming subscriptions

Insert a few rows in messages and channel_users, then try a streaming subscriptions:

subscription {
  messages_stream(cursor: {initial_value: {id: 0} }, batch_size: 5) {
    id
    message
    author_id
  }
}