connect: add path to node #5206
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This commit adds support for adding a path to a connect node, allowing for JSON selections to be built as the query planner traverses the connect-specific graph.
nicholascioli
requested review from
dariuszkuc,
sachindshinde,
goto-bus-stop and
SimonSapin
as code owners
apollo-federation/src/sources/connect/fetch_dependency_graph/mod.rs
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apollo-federation/src/sources/connect/fetch_dependency_graph/mod.rs
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apollo-federation/src/sources/connect/fetch_dependency_graph/mod.rs
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apollo-federation/src/sources/connect/fetch_dependency_graph/mod.rs
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Reviewed the logic for add_path() here, looks fine to me!
(One thing I've mentioned in DMs is that the way we compare Values currently cares about the order of fields in object values when we don't want it to, but this will be fixed across the codebase in a later PR.)
| Selections { | ||
| /// Property path from the head |
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The gist here is that the JSON selection grammar starts with
JSONSelection ::= NakedSubSelection | PathSelection
NakedSubSelection ::= NamedSelection* StarSelection?
In the case where JSONSelection is a PathSelection, note that PathSelection is really just a non-empty vector of Keys, potentially followed by a SubSelection. In the case where JSONSelection is a NakedSubSelection, it's really just a SubSelection without braces (which may be empty, and can be thought of as a PathSelection with an empty vector of Keys).
So to support that initial vector of Keys, we have head_property_path. (I think part of the confusion may come from calling it a "path"; maybe just calling it head_keys is better?)
| tail_selection: Option<(Name, PathTailSelection)>, | ||
| }, | ||
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| /// The full selection from a (potentially) different root |
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This selection starts at the "root", similarly to PathSelections::Selections. (Or rather, when I'm saying "root", I mean the root of the JSON data returned by the API call; I'm not sure what "different root" means here.)
| selection: JSONSelection, | ||
| }, | ||
| } | ||
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| /// A path to a specific selection, not from the root. |
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I wouldn't necessarily say this a path to a specific selection (this is more like the final selection of a path, though you mention that below).
| #[derive(Debug, Clone)] | ||
| pub(crate) enum PathTailSelection { | ||
| /// Simple selection using a chain of keys. |
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To clarify a bit, this represents the case where a selection returns a value that represents a GraphQL enum value or built-in scalar, in which case the data represents a NamedSelection without any trailing SubSelection.
| Selection { | ||
| /// The chain of [Key]s to traverse |
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Mentioned it above, but I'm wondering whether it'd be less confusing to call this e.g. keys instead of property_path to avoid referencing the word "path".
| path_selection: PathSelection, | ||
| }, | ||
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| /// Custom selection using a [PathSelection] |
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I'm not sure if "custom selection" is the right phrase here, it's more of a selection that returns a GraphQL custom scalar (similarly below).
This commit adds support for adding a path to a connect allowing for JSON selections to be built as the query traverses the connect-specific graph.
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