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Graph/dto-mapping-nested-list

Pattern

DTO Mapping for Nested Lists

dto-mapping-nested-list

A recurring schema-shape mismatch where shared ORM/DB models cause automatic serialization of nested objects instead of the API’s simpler field types, leading to explicit DTO separation or validators that map object attributes into primitives.

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Updated5/1/2026

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30 linked nodes

@ts-check with Zustand slices and JSDoc does not type-check the bound store correctly

I haven't fully grasped zod's schema so I'm a little stuck on how to implement this — one of the questions want the user to select a checkbox (or multiple checkboxes). Tension: I tried changing around the schema a couple times, I even mapped through an array of the items I wanted to be checked and rendered them as checkboxes but I was unsuccessful.

Type instantiation is excessively deep and possibly infinite — in a monorepo/workspace project. Tension: on seemingly benign types like this. Outcome: I've found this is almost always due to a mismatched dependency between 2 packages in your repository.

Normally, the response looks like this: — I have a model, called Candidate that I'm trying to return, two of the fields refer to another model, StaffMember. Tension: However, I don't want any nested fields.

ValueError: has no matching SQLAlchemy type — class Category(SQLModel, table=True). Tension: referring to the `category.py` field `todos: list["Todo"]`, while the relation `hero/team` does work. Outcome: I encountered this issue when I tried to define field with `list[str]` type.

that will give me 3 levels deep of nodes in my json output — I have a many to many self referential relationship. Tension: is there a way to do that so it goes as many levels deep as needed until nodes = [] ? Outcome: Do I need to use something like marshmallow-sqlalchemy ?

String literals such as `toys:["ToyResponse"]`, this method still causes circular import errors. Tension: you are still importing the class to resolve the type. Outcome: doesnt work when a child import a parent.

cannot adapt type 'dict' using placeholder '%s' (format: AUTO) — running query below query i'm getting error. Tension: I want check whether the particular email template is used in any other model instance and model Rule we have action(JSONB). Outcome: Rather than trying to construct a JSON literal in SQLAlchemy you could let Postgres do it using the `jsonb_build_object` function.

PermissionSchema.model_validate(permission) cannot build a schema from an SQLModel instance

The `exclude_none` parameter to `model.model_dump` would apply to all entries of response, so it is not suitable. — Response is serialized/dumped as a JSON. Tension: I want attr2 to be included only if it is non-null. Importantly, `stuff1` should be included regardless of its type (null or int). Outcome: Pydantic v2 has custom serialization which allows one to control how objects are converted to JSON, but I am using 1.10.

FastAPI does not know about Lizard, Dog and Cat schemas in OpenAPI

SQLModel/Pydantic serializes the `categories: list[Category]` field as nested objects, but the API response needs `categories` as `list[str]` containing `Category.name` values.

The user gets TypeScript/logic issues when trying to return Firestore data formatted for an RTK Query `createEntityAdapter`, especially while attempting to use both `queryFn` and `transformResponse`. The endpoint also fails because `queryFn`/return shape expectations conflict with how `transformResponse` is meant to operate.

There is no example on how to use enum mapping with postgres and hibernate 6. — I am migrating from hibernate 5 to 6. Tension: As @TypeDef is no more available I don't know how I can map my enum type to my database column.

This only give me the Event type without the nested `Owner` property/relation. — I have a model with a relation to a separate model. I’m now querying the object and the related object. Tension: But how do I get a typescript type so that I can pass this object to subcomponents of my react component? Outcome: This only give me the Event type without the nested `Owner` property/relation.

it seems that is not working for me — Spring Data Couchbase and I have an entity that maps some of the fields of a document. Tension: I need all the other fields to be mapped to a Map<String, Object>.

org.hibernate.query.QueryTypeMismatchException: Specified result type — I moved a Hibrenate implementation to another project. From com.mvc.data to com.mvc.frontend. Tension: Notice that it's the same type. Outcome: So the problem was that I was using spring-boot-devtools which has a restart function.

A complex native SQL query in Spring Boot 3.4.3 is executed with @Query(nativeQuery=true) but the result cannot be mapped directly into the FindAvailableEventResponseDto record.

a fundamental property of value objects is that they should not be null — your `BankUpdateRequest`. Tension: which conflicts with the optional fields in your `BankUpdateRequest`. Outcome: allow `null` in DTOs.

I would like to use an existent Parent instance to create a child instance — with lombok Annotations. Tension: with all parent fields filled, and be able to complement with child properties. Outcome: instead of a parent's "field by field" solution.

the `"type"` property is missing from the array elements in the obfuscated form — after running through ProGuard. Tension: This causes Jackson to deserialize those objects incorrectly. Outcome: allows the example to run successfully even after obfuscation.

I want to use this CRUD service when my class is serialized — I have a CRUD service in Spring Boot, and I'm using a custom serializer with a class that extends `JsonSerializer`. Tension: I've tried several approaches without success.

A container entity needs to persist a List of objects whose types are subclasses of a common base class. Because the base is annotated with @MappedSuperclass, attempts to map the list using generics/relationship annotations fail.

Using a single @SequenceGenerator definition in a mapped superclass causes Product and Order entities to share the same database sequence, so ids are generated from the same sequence. The goal is to have separate sequence names per entity without relying on Hibernate-specific generator classes.

{ "a": "this-is-ignored", "b": "uses-this-value" }. Tension: It works perfect when either `a` or `b` are present, and when both are present and `b` comes after `a`. Outcome: custom deserializer for whole class.

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.

List<Map<String, Object>> getOption_list() not work — I have a native query in JPA. Tension: The result of option_list is [{"image": "image1", "option": "L"}, {"image": "image2", "option": "X"}] in db.

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

Hibernate ORM doesn’t bother checking if a collection element is deeply equal to an element of the initial state — @ElementCollection(fetch = FetchType.EAGER). Tension: the user passes the fields they want. Outcome: avoid replacing objects in that case.

TS2353: Object literal may only specify known properties, and 'id' does not exist in type '[id: string, type: string, ...]' — The API serializer (graph.ts) used object literals typed as CompactNodeTuple/CompactEdgeTuple. Tension: tuples don't accept named object keys.

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