Refetch transit leg with node query of GTFS GraphQL API #6045

vesameskanen · 2024-09-05T10:42:58Z

Summary

GTFS leg object now includes a graphql node id . Transit leg can be refetched using the Node query:

query legQuery { node(id: "foo") { ... on Leg { mode start { estimated { time } } } } }

Such query can be used to update an itinerary and to detect if the itinerary is no longer possible because of delays or canceled trips.

Non-transit legs cannot be refetched - the response is always null.

This PR also adds missing implementation for querying leg's realtimeState via GTFS graphql API.

Documentation

In the graphql schema.

leonardehrenfried · 2024-09-05T10:47:22Z

@binh-dam-ibigroup This might be interesting for you.

@vesameskanen I almost cannot believe that it is so easy!

codecov · 2024-09-05T10:54:54Z

Codecov Report

Attention: Patch coverage is 75.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 69.79%. Comparing base (d2f4b2d) to head (20f855a).
Report is 91 commits behind head on dev-2.x.

Files with missing lines	Patch %	Lines
...pplanner/apis/gtfs/datafetchers/QueryTypeImpl.java	0.00%	4 Missing ⚠️
...anner/apis/gtfs/datafetchers/NodeTypeResolver.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #6045      +/-   ##
=============================================
+ Coverage      69.74%   69.79%   +0.04%     
- Complexity     17316    17364      +48     
=============================================
  Files           1960     1962       +2     
  Lines          74267    74380     +113     
  Branches        7603     7627      +24     
=============================================
+ Hits           51796    51910     +114     
+ Misses         19829    19827       -2     
- Partials        2642     2643       +1

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leonardehrenfried · 2024-09-05T10:57:19Z

src/main/java/org/opentripplanner/apis/gtfs/datafetchers/QueryTypeImpl.java

@@ -445,6 +447,15 @@ public DataFetcher<Object> node() {
 // TODO: Add geometry
 return new NearbyStop(stop, Integer.parseInt(parts[0]), null, null);
 }
+ case "Leg":
+ if (id.equals("null") || id.isBlank()) {


Do we really want to treat the string "null" specially? In what case can this happen?

It seems that Leg base class retuns null in getLegReference() method, and that value gets encoded into relay id. Decoding the relay id produces a string value 'null'.

I added the check to prevent unhandled exception when somebody tries to refetch non-transit legs. Maybe there is a more elegant way to handle such situations.

Now the response for non-transit legs is
"data": { "node": null }

How about checking if the reference returns null in LegImpl and never return the string "null" but the null value?

Seems like a better solution. We should make the id field nullable in that case.

I tried making id of Node type nullable and everything seems to work fine.

Another option would be to encode null as an empty string in LegReferenceSerializer, in which case id.isBlank() test would work. This might also fix problems in transmodel api.

leonardehrenfried · 2024-09-05T10:57:55Z

src/main/resources/org/opentripplanner/apis/gtfs/schema.graphqls

@@ -611,7 +611,7 @@ type Itinerary {
 walkTime: Long
 }

-type Leg {
+type Leg implements Node {


I'm pretty sure this is backwards-compatible but lets discuss in the dev meeting.

I'm almost 100% sure it is.

I tried to do some research on this, but could not find anything. So, lets change it and see what happens - maybe wait with merging this PR after the next release?

optionsome · 2024-09-05T12:23:51Z

@vesameskanen I almost cannot believe that it is so easy!

This is easy because this was already done in the transmodel API. However, the transmodel API has own legs query for this because it lacks the node query/interface.

optionsome · 2024-09-05T12:26:14Z

@vesameskanen will still add some integration tests for this.

vesameskanen · 2024-09-06T08:19:56Z

GTFS integration tests currently cannot test leg refetching, because mocked itineraries lack essential data used in encoding the leg information. Integration test now tests only that legs contain the id.

optionsome · 2024-09-06T11:07:11Z

src/main/java/org/opentripplanner/apis/gtfs/datafetchers/LegImpl.java

+ public DataFetcher<Relay.ResolvedGlobalId> id() {
+ return environment -> {
+ var ref = getSource(environment).getLegReference();
+ var id = (ref == null) ? "" : LegReferenceSerializer.encode(ref);


Yesterday in the developer meeting we thought it might make sense to use some special string like "NotAvailable" instead of "null" or empty string.

optionsome · 2024-09-06T11:13:12Z

src/main/resources/org/opentripplanner/apis/gtfs/schema.graphqls

@@ -669,6 +669,8 @@ type Leg {
 For non-transit legs, null.
 """
 headsign: String
+ "An identifier for the leg, which can be used to re-fetch transit leg information."


Maybe we should also mention that an invalid reference id is returned for other legs. Also, mention that the id might not be usable forever since the data and ids within data can change over time.

Also, move all encoding/decoding logig to LegReferenceSerializer class.

optionsome · 2024-09-09T07:35:25Z

src/main/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializer.java

@@ -26,7 +28,7 @@ private LegReferenceSerializer() {}
 @Nullable
 public static String encode(LegReference legReference) {
 if (legReference == null) {
- return null;
+ return notAvailable;


Since u change this, do you also need to update the transmodel API handling of missing value?

Transmodel API works as expected. null is encoded as 'NotAvailable' and 'NotAvailable' is decoded as null.

The only change I can think of is maybe removing isBlank() check from TransmodelGraphQLSchema.java.

vesameskanen · 2024-09-11T11:19:14Z

I tested new legs with relay and got lots of problems. Relay does not accept nodes with same node id but different content. Either all leg types must be serialized to unique id ('NotAvailable' is not OK), or we have to revert node interface for legs and add a dedicated leg query. Any opinions?

leonardehrenfried · 2024-09-11T13:35:33Z

Maybe I don't get it but don't all legs have the same type in GraphQL?

optionsome · 2024-09-12T07:55:47Z

Maybe I don't get it but don't all legs have the same type in GraphQL?

@vesameskanen explained to me that the issue is that the non-transit legs all have the same id. We discussed this today and thought maybe the solution would be to generate unique ids based on actual leg data (such as departure/arrival time) even if we don't support refetching based on those ids.

I tried adding tests for refetching the legs through the node query in the graphql integration tests on Tuesday but creating/maintaining such test would be slightly difficult.

optionsome · 2024-09-17T13:23:29Z

src/main/java/org/opentripplanner/apis/gtfs/datafetchers/LegImpl.java

+ String.join(
+ "",
+ leg.start().time().toString(),
+ leg.end().time().toString(),
+ leg.getFrom().toStringShort(),
+ leg.getTo().toStringShort()
+ );


Unlike the transit leg references, this is now not "double base64 encoded" (for transit the original reference is already base64 encoded and then encoded again with the leg: prefix). I wonder if we should encode this as well or not.

I like that this is only on the GTFS API so it doesn't potentially break transmodel clients who might rely on the fact that non-null ids are refetchable-

optionsome · 2024-09-17T13:28:02Z

src/main/java/org/opentripplanner/model/plan/Leg.java

@@ -244,6 +245,10 @@ default boolean getRealTime() {
 return false;
 }

+ default RealTimeState getRealTimeState() {
+ return RealTimeState.SCHEDULED;


I don't know if it's better to return SCHEDULED or null? SCHEDULED for street legs feels a bit wrong, on the other hand that's how it worked in otp1 seemingly.

optionsome · 2024-09-17T13:30:06Z

src/main/java/org/opentripplanner/model/plan/ScheduledTransitLeg.java

@@ -427,6 +433,7 @@ public String toString() {
 .addEnum("alightRule", getAlightRule())
 .addObj("transferFromPrevLeg", transferFromPrevLeg)
 .addObj("transferToNextLeg", transferToNextLeg)
+ .addEnum("realtimeState", getRealTimeState())


Not sure if we should add this to the toString as this is not Leg's own field.

optionsome · 2024-09-19T18:34:27Z

We discussed this pr again in the dev meeting today and came to the conclusion that it's better to create own leg(id) query for the refetching purpose because the node query is more fit for limited number of entities stored in a database, for example, and for legs, we don't really have the ability to refetch all types of legs currently. The field on leg can still be called id but it should be nullable and we should return null for non-transit legs.

vesameskanen added 3 commits September 3, 2024 12:06

GTFS graphql API supports querying itinerary leg status

5e18c0a

Catch non-transit legs properly

021e07c

Add type resolver for Leg

01b460d

vesameskanen requested a review from a team as a code owner September 5, 2024 10:42

leonardehrenfried changed the title ~~Add support for refetching transit leg using the node query of GTFS graphql API~~ Refetch transit leg with node query of GTFS Graphql API Sep 5, 2024

leonardehrenfried changed the title ~~Refetch transit leg with node query of GTFS Graphql API~~ Refetch transit leg with node query of GTFS GraphQL API Sep 5, 2024

Fix formatting

2182066

leonardehrenfried reviewed Sep 5, 2024

View reviewed changes

vesameskanen added 3 commits September 6, 2024 08:57

Do not encode null reference as 'null' string

7e2033f

More accurate docs about leg query

6b92741

Add leg id to plan query test

e489f05

optionsome reviewed Sep 6, 2024

View reviewed changes

vesameskanen added 2 commits September 9, 2024 09:48

Use self-documenting value for non-transit leg ids

6bd5d04

Also, move all encoding/decoding logig to LegReferenceSerializer class.

Add more docs about leg re-fetching into gtfs graphql schema

a998e52

optionsome reviewed Sep 9, 2024

View reviewed changes

vesameskanen added 2 commits September 11, 2024 08:33

Support querying leg's realTimeState in GTFS graphql api

cf37e89

Query realtimeState in extended plan test

cd54cbe

vesameskanen marked this pull request as draft September 11, 2024 11:15

vesameskanen added 3 commits September 13, 2024 08:23

Revert LegReferenceSerializer changes

4025d5b

Generate unique id for non-transit legs

b206ce1

Restore LegReferenceSerializer null test

15f1f34

Update plan-extended expoctations to use unique leg ids

20f855a

vesameskanen marked this pull request as ready for review September 13, 2024 05:56

optionsome requested review from optionsome and leonardehrenfried September 17, 2024 09:23

optionsome reviewed Sep 17, 2024

View reviewed changes

t2gran added this to the 2.7 (next release) milestone Sep 18, 2024

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Refetch transit leg with node query of GTFS GraphQL API #6045

Refetch transit leg with node query of GTFS GraphQL API #6045

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Refetch transit leg with node query of GTFS GraphQL API #6045

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Refetch transit leg with node query of GTFS GraphQL API #6045

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