Merge pull request #46 from vulcanize/db_triggers2

triggers for tables to emit graphql notifications

README.md

@@ -186,6 +186,34 @@ e.g.
 This will stand up a Postgraphile server on the public and eth schemas- exposing GraphQL endpoints for all of the tables contained under those schemas.
 All of their data can then be queried with standard [GraphQL](https://graphql.org) queries.
 
+Also, graphql subscription is available. Using the following query you will be notified when new data come in.
+For `topic` use table name.
+
+e.g.
+
+```
+subscription MySubscription {
+  listen(topic: "receipt_cids") {
+    relatedNodeId
+    relatedNode {
+      nodeId
+      ... on ReceiptCid {
+        id
+        contract
+        contractHash
+        logContracts
+        topic0S
+        topic1S
+        topic2S
+        topic3S
+        txId
+      }
+    }
+  }
+}
+
+```
+
 * Use PG-IPFS to expose the raw IPLD data. More information on how to stand up an IPFS node on top
 of Postgres can be found [here](./documentation/ipfs.md)
 

db/migrations/00013_potgraphile_triggers.sql

@@ -0,0 +1,70 @@
+-- +goose Up
+-- +goose StatementBegin
+create function eth.graphql_subscription() returns trigger as $$
+declare
+    table_name text = TG_ARGV[0];
+    attribute text = TG_ARGV[1];
+    id text;
+begin
+    execute 'select $1.' || quote_ident(attribute)
+        using new
+        into id;
+    perform pg_notify('postgraphile:' || table_name,
+                      json_build_object(
+                              '__node__', json_build_array(
+                              table_name,
+                              id
+                          )
+                          )::text
+        );
+    return new;
+end;
+$$ language plpgsql;
+-- +goose StatementEnd
+
+CREATE TRIGGER header_cids_ai
+    after insert on eth.header_cids
+    for each row
+    execute procedure eth.graphql_subscription('header_cids', 'id');
+
+CREATE TRIGGER receipt_cids_ai
+    after insert on eth.receipt_cids
+    for each row
+    execute procedure eth.graphql_subscription('receipt_cids', 'id');
+
+CREATE TRIGGER state_accounts_ai
+    after insert on eth.state_accounts
+    for each row
+    execute procedure eth.graphql_subscription('state_accounts', 'id');
+
+CREATE TRIGGER state_cids_ai
+    after insert on eth.state_cids
+    for each row
+    execute procedure eth.graphql_subscription('state_cids', 'id');
+
+CREATE TRIGGER storage_cids_ai
+    after insert on eth.storage_cids
+    for each row
+    execute procedure eth.graphql_subscription('storage_cids', 'id');
+
+CREATE TRIGGER transaction_cids_ai
+    after insert on eth.transaction_cids
+    for each row
+    execute procedure eth.graphql_subscription('transaction_cids', 'id');
+
+CREATE TRIGGER uncle_cids_ai
+    after insert on eth.uncle_cids
+    for each row
+    execute procedure eth.graphql_subscription('uncle_cids', 'id');
+
+-- +goose Down
+drop trigger uncle_cids_ai on eth.uncle_cids;
+drop trigger transaction_cids_ai on eth.transaction_cids;
+drop trigger storage_cids_ai on eth.storage_cids;
+drop trigger state_cids_ai on eth.state_cids;
+drop trigger state_accounts_ai on eth.state_accounts;
+drop trigger receipt_cids_ai on eth.receipt_cids;
+drop trigger header_cids_ai on eth.header_cids;
+
+drop function eth.graphql_subscription();
+