feat(network-subgraphs): Add idAsString field (#1024)

Added new field to `Stream` entity: `Stream#idAsString`. It has same
value as in the `id` field. The field allows us to do substring queries
for the field id (by using `idAsString_contains` where clause).

This feature is needed e.g. in
streamr-dev/network#3132.

Author: teogeb

packages/network-subgraphs/schema.graphql

@@ -35,6 +35,8 @@ type StreamPermission @entity {
 type Stream @entity {
   "stream ID = 'creator address'/'path' where path can be any string"
   id: ID!
+  "This field has the same value as the ID field. It enables us to perform substring queries on the id field using the idAsString_contains where clause"
+  idAsString: String! @index
   "Stream metadata JSON"
   metadata: String!
   "Permissions that each Ethereum address owns to this stream"

packages/network-subgraphs/src/streamRegistry.ts

@@ -20,6 +20,7 @@ export function handleStreamCreation(event: StreamCreated): void {
         return
     }
     let stream = new Stream(event.params.id)
+    stream.idAsString = event.params.id
     stream.metadata = event.params.metadata
     stream.createdAt = event.block.timestamp
     stream.updatedAt = event.block.timestamp
@@ -37,7 +38,15 @@ export function handleStreamUpdate(event: StreamUpdated): void {
         [event.params.id, event.params.metadata, event.block.number.toString()])
     let stream = Stream.load(event.params.id)
     if (stream === null) {
+        // If the stream was initialized using the trustedSetStreamMetadata() method instead of the usual createStream(), 
+        // the Stream entity does not yet exist. This pattern was used at least in the brubeck-migration-script 
+        // (see https://github.com/streamr-dev/network-contracts/pull/1007), and possibly also in ENS stream creation
+        // (see https://github.com/streamr-dev/network-contracts/pull/109).
+        // The trustedSetStreamMetadata() method, which existed in StreamRegistry before version 5, only emitted 
+        // the StreamUpdated event. Since no StreamCreated event was triggered during this process, the handleStreamCreation() 
+        // function was not called, and therefore the Stream entity wasn't created. For this reason we need to create it here.
         stream = new Stream(event.params.id)
+        stream.idAsString = event.params.id
         stream.createdAt = event.block.timestamp
     }
     stream.metadata = event.params.metadata