René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Dependency graph design","articleBody":"I want to capture here some thoughts about the Dependency graph (see #1409).\r\n\r\nOne of the main challenges is the dynamic aspects of a query (type conditions). \r\n\r\nFor exampel for this schema:\r\n```graphql\r\ntype Query{ \r\n    node: Node\r\n}\r\ninterface Animal {\r\n    name: String\r\n    friends: [Friend]\r\n}\r\n\r\nunion Pet = Dog | Cat\r\n\r\ntype Friend {\r\n    name: String\r\n    isBirdOwner: Bool\r\n    isCatOwner: Bool\r\n    pets: [Pet] \r\n}\r\n\r\ntype Bird implements Animal {\r\n   name: String \r\n   friends: [Friend]\r\n}\r\n\r\ntype Cat implements Animal{\r\n   name: String \r\n   friends: [Friend]\r\n   breed: CatBreed \r\n}\r\n\r\ntype Dog implements Animal{\r\n   name: String \r\n   breed: DogBreed\r\n   friends: [Friend]\r\n}\r\n\r\nscalar DogBreed\r\nscalar CatBreed\r\n```\r\none can imagine this query:\r\n\r\n```graphql\r\n{\r\n  node\r\n  ... on Cat {\r\n    friends {\r\n      isCatOwner\r\n      name\r\n      pets {\r\n        name\r\n        ... on Cat {\r\n          breed\r\n        }\r\n      }\r\n    }\r\n  }\r\n  ... on Bird {\r\n    name\r\n    friends {\r\n      isBirdOwner\r\n      name\r\n      pets {\r\n        name\r\n        ... on Dog {\r\n          breed\r\n        }\r\n      }\r\n    }\r\n  }\r\n  ... on Dog {\r\n    name\r\n  }\r\n}\r\n\r\n```\r\n\r\nThe question is now how the dependency graph should capture these dynamic type conditions. \r\nOne possible way could be this:\r\n\u003cimg width=\"1041\" alt=\"Screen Shot 2019-06-10 at 11 15 36 am\" src=\"https://user-images.githubusercontent.com/1706744/59166846-1c11ba80-8b71-11e9-89cc-bf488405a91b.png\"\u003e\r\n\r\nBut the value of this kind of dependency graph maybe limited because it doesn't uphold to one fundamental expectation that every field is only present once.\r\nThe `/node/friends/pets/name` field is duplicated because it will only be executed if we have a `Bird` or a `Cat`, but not for a `Dog`. \r\n\r\nSame is true for `/node/friends/pets` and `/node/friends/name`.\r\n\r\nThe alternative could maybe look like this:\r\n\u003cimg width=\"890\" alt=\"Screen Shot 2019-06-10 at 11 34 45 am\" src=\"https://user-images.githubusercontent.com/1706744/59167289-cb4f9100-8b73-11e9-86da-3968f5e46639.png\"\u003e\r\n\r\n\r\n\r\nIt doesn't duplicate any fields anymore but now there are complex conditions associated with some nodes. For example `/node/friends/pets/breed` will only be evaluated if the original node is a `Cat` and the pet is a `Dog`.\r\n\r\n","author":{"url":"https://github.com/andimarek","@type":"Person","name":"andimarek"},"datePublished":"2019-06-10T01:30:22.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":18},"url":"https://github.com/1566/graphql-java/issues/1566"}