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Graph/67a88b5d-df61-4a2e-aea4-8cf41277d1eb

Domainunvalidated

Collection Mapping

67a88b5d-df61-4a2e-aea4-8cf41277d1eb

Collection Mapping

Node Details

Public graph metadata

Updated5/1/2026

PageRank0.0000

Effectiveness0.000

Connections

13 linked nodes

PERTAIN_TOProblem

java.lang.IllegalStateException: Duplicate key a (attempted merging values 1 and 1) — I'm trying to convert a list of objects to a `Map` using Java Streams. Tension: I expected it to just create a map with unique keys, but I forgot that my list has duplicates.

PERTAIN_TOSolution

You can use `Collectors.collectingAndThen`, but then you need to keep a list of the grouped values so you can access the nail index later — Collectors.collectingAndThen. Tension: you need to keep a list of the grouped values so you can access the nail index later.

PERTAIN_TOProblem

incompatible types: java.util.List cannot be converted to java.util.List — List strings = new ArrayList<>(); List objs = (List)strings;. Tension: I would expect this to fail to compile for the same reason, but it doesn't. Outcome: I can even use it with the same classes.

PERTAIN_TOProblem

This works when I fetch into a record, but not my own pojo — I have tried many different variations including passing Long[].class to DSL.field. Tension: I just get the following. Outcome: please make sure it accommodates fetching multiple arrays of ids related to TEACHER with corresponding where/and clauses.

PERTAIN_TORootCause

With a List or Map, @MappedCollection.keyColumn maps the collection index or map key column, so the schema must store that value

PERTAIN_TOProblem

@MappedCollection.keyColumn is invalid for a List without a matching index column

PERTAIN_TOSolution

Add an index column to the collection table and map it with @MappedCollection, or switch to a Set and remove keyColumn

PERTAIN_TOAnswer

PERTAIN_TOAnswer

PERTAIN_TOSolution

The simplest way seems to be `MULTISET_AGG()`, in this case: — `ctx.select(CATALOG.AUTHOR,. Tension: I want to fetch the table into a `Catalog` POJO. Outcome: Assuming you have the appropriate constructors on those classes, of course.

PERTAIN_TOAnswer

PERTAIN_TOSolution

You need to help it do it with a converter — Spring is trying to convert the string `[{"name": "testName", "email": "testEmail}]` to a contact list `List`.

PERTAIN_TOAnswer

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