Creates a DTO (Data Transfer Object) class for an entity. Use this skill when a DTO class needs to be created, either standalone or as part of a larger task (e.g. REST controller, service layer, replacing entity usage with a DTO).
Installation
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Creates a DTO (Data Transfer Object) class for an entity. Use this skill when a DTO class needs to be created, either standalone or as part of a larger task (e.g. REST controller, service layer, replacing entity usage with a DTO).
Preflight: Spring MCP
This skill is part of the Spring Agent Toolkit and is designed to work with the Spring MCP server (provided by the Amplicode IntelliJ plugin). Before doing anything else, check your tool list for any Spring MCP tool — they are exposed under the amplicode MCP server (e.g. get_project_summary, list_module_dependencies, get_entity_details); harnesses that flatten MCP tools into the tool list use the mcp__amplicode__ prefix on the same names.
If at least one Amplicode tool is available — MCP is connected. Proceed with the skill below.
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DTO Creator
Creates a DTO class (Java class, Java record, Java+Lombok, or Kotlin data class) for an entity with selected attributes, constructors, getters/setters, equals/hashCode, toString, and optional features.
CRITICAL: Code ONLY from examples/ files. If no matching example -- STOP and ask user.CRITICAL: For questions with a fixed set of choices, prefer AskUserQuestion > its analogue > plain text list. Plain numbered text lists are the last resort when no interactive tool is available.CRITICAL: Read the conversation context BEFORE running Step 1. Half the questions in Steps 2–7 may already be answered by the user's prompt and prior turns. Re-asking what was already said is the #1 reason this skill feels slow.
Step 7 (mapper) is automatic when conversion is needed. If from context it is clear that the DTO will be used in code that converts entities to/from DTOs (controller, service, endpoint replacement, etc.), the skill MUST delegate to mapper-creator — never write manual mapping code inline. The mapper-creator skill decides the implementation (MapStruct, Custom, adding dependencies) — this skill just delegates.
Defaults
Option
Default
Always ask?
Notes
entity
--
YES
main branching: which entity to create DTO for
attributes
all entity fields
YES
which fields to include
className
{EntityName}Dto
NO
suggest, confirm only
language
from get_project_summary
NO
auto-detected
variant
auto from language + deps
YES
Java class / Java record / Java+Lombok / Kotlin
mutable
false
NO
skip unless user wants customization
allArgsConstructor
true
NO
Java plain only
equalsHashCode
true
NO
Java plain only
toString
true
NO
Java plain only
fluentSetters
false
NO
only when mutable=true, Java only
jsonIgnoreUnknownProperties
false
NO
Java only, when Jackson on classpath
serializableType
NoSerializable
NO
rarely needed
packageName
same package as entity
NO
auto-detected
subDtoType (per ToOne association)
FLAT with id-only sub
YES
Four options available: New Class / New Nested Class / Existing Class / Flat. "Only ID" does NOT exist as a separate option — it is Flat with only the sub-entity id checked. See references/sub-dto.md.
subDtoType (per ToMany / collection)
NEW_NESTED_CLASS
YES
same 4 options as ToOne. Flat IS supported for collections and produces composite plural fields like Set<Integer> specialtyIds — see references/sub-dto.md.
fieldNameOverride (per field)
none
NO
per-field rename
extraValidations (per field)
none
NO
user-added jakarta validators on top of inherited ones
removedValidations (per field)
none
NO
constraints inherited from entity that the user wants dropped
indent
from .editorconfig (fallback 4-space)
NO
see § Indentation below
Smart defaults: If user says "use defaults", "all defaults", "default settings",
or similar -- skip ALL questions where "Always ask?" = NO. Only ask mandatory questions.
Smart answer recognition: When user provides a value instead of choosing from a numbered
list, accept it directly. Examples:
Question "Which entity?" -> user answers "Order" -> this IS the entity, don't re-ask
Question "Variant?" -> user answers "record" -> this IS Java record, don't show options
If user provides multiple answers in one message -> accept all, skip answered questions
NEVER ask a question that the user already answered (even implicitly)
Batch questions: Group closely related questions into a single
AskUserQuestion call (up to 4 questions per call) when they:
Belong to the same logical section (e.g. both are Java method generation settings)
Don't depend on each other's answers
Have obvious defaults that the user can skip
Rules:
Maximum 3-4 questions per AskUserQuestion call
Mark the recommended option with (Recommended) and place it first
Never batch questions from DIFFERENT decision branches
The primary branching question (entity selection, variant) is always asked ALONE
Prefer AskUserQuestion for choices; fall back to plain text lists only if the tool is unavailable
Decision-making principle — context first, then ask
Before asking the user any question, attempt to derive the answer from
the context already gathered: project summary, module dependencies, entity
details, existing files in the package, prior turns of this conversation,
and the user's original prompt. Only ask when the context yields no
clear default or when the choice is genuinely user-specific (e.g. which
entity, which fields).
Hierarchy of decisions:
Context is unambiguous → decide silently, do NOT ask.
Examples: language and JDK from get_project_summary; Lombok / Jackson /
Hibernate Validator from list_module_dependencies; package from the
entity FQN; className from {Entity}Dto; back-reference @ManyToOne
filtering; auto-selection of sub-entity scalars; record vs. plain class
when JDK ≥ 16 and no Lombok and the user did not request otherwise.
Exception: subDtoType is NEVER decided silently — it always requires
at minimum principle 2 (one-line confirmation), unless the USER explicitly
stated the shape in their own message (not in ARGUMENTS).
Context gives a strong signal → state the decision + alternatives in one line, let the user override or stay silent.
Format:
Will create `ScheduleTemplateDto` as a Java record with nested `SlotDto` (record).
Alternatives: plain class, Lombok, separate file for SlotDto. OK?
The user can answer "ok" / "yes" / silence → accept; or name an
alternative → switch. This is not the same as the numbered question
format — it is a single confirmation line.
Context yields no clear default → ask with AskUserQuestion (preferred) or its analogue, with the recommended option first.
When AskUserQuestion is available, use it with preview fields so the
user sees the concrete code shape for each option. Mark the recommended
option with (Recommended) in its label and place it first. If no
interactive choice tool is available, fall back to a plain text list.
Never ask iteratively ("which variant?" → user picks → "which fields?" → …)
when one batched call would do.
Context is fully empty for a critical input → ask plainly.
This applies to: which entity, which fields (when not "all"), the
user's intent itself.
How to ask — prefer AskUserQuestion
When a question must be asked, prefer the AskUserQuestion tool (or
its analogue) over writing a numbered list in the response body. Fall back
to plain text only if no interactive choice tool is available.
Rules for AskUserQuestion calls in this skill:
Each call may contain up to 4 questions that are independent of each
other (the tool will render them together). Use this to batch related
decisions in one round-trip.
Each question has 2–4 options. The tool auto-adds an "Other" choice
for free-form input — never include it manually.
Mark the recommended option by putting it first with (Recommended)
appended to the label.
Use multiSelect: true for "which fields to include" or "which
validators to add" — anything where multiple answers are valid.
header is a 12-char chip label (e.g. "Variant", "Sub-DTO", "Fields").
Each option has a description explaining what the choice means or its
consequence (one short sentence).
When AskUserQuestion is not the right tool:
Free-form input where there is no enumerable set of options
(e.g. arbitrary class name, arbitrary field rename) — ask in plain text.
The "single confirmation line" form from principle 2 — that is a plain
question with an obvious yes/no, not an enumerated choice.
The screen-driven question lists in Steps 2–5 below are a fallback for
case 4. They are NOT a script to execute top-to-bottom. If a question's
answer is already determined by principles 1–3, skip the question.
Plugin-wizard fidelity is not a goal — generation correctness is. The
plugin's UI exists because a screen can show many controls at once; a
chat cannot, so the skill must compensate by deciding more on its own.
Step 0 -- Conversation context first (REQUIRED, no tool calls)
Before any MCP call, before any question, re-read the user's prompt and
the prior turns of this conversation and extract whatever is already
stated. This step costs nothing and prevents the most common failure mode
of this skill — asking the user something they already said.
Build a mental checklist of inputs and tick off everything the user has
already provided, explicitly or implicitly:
Input
Look for in the prompt / context
entity
a class name (Vet, Owner, ScheduleTemplate); "for X"; an open file in the IDE; a file path; a recently discussed entity in this conversation
purpose
"for REST", "for controller", "for API", "for mapping", "projection", "for service" — drives field selection and the mapper question
fields
"all fields", "only id and name", "without password", "with associations", "flat"
variant
"record", "plain class", "Lombok", "data class" — also implied by language: Kotlin → data class, no question
mapper
"and mapper", "with mapper", "only DTO", "no mapper"
className
"name it OwnerSummaryDto", "class Foo"
package
"in package …", "next to controller"
smart defaults
"use defaults", "all defaults", "default settings", "as usual"
sub-DTO shape
"nested", "separate class", "only id", "flat"
prior project facts
language, JDK, dependencies — already known if discussed earlier in this conversation; do not re-fetch
For every input that is explicitly or strongly implicitly answered:
mark it as decided and skip the corresponding question in Steps 2–7. Do
NOT ask "what entity?" if the user wrote "create DTO for Vet" — Vet is
the answer. Do NOT ask "Java record or class?" if the user wrote "make
record DtoX" — record is the answer.
For every input that is not answered: defer to the Decision-making
principle below — try to derive it from project context first (Step 1),
and only then ask.
CRITICAL: ARGUMENTS ≠ user intent. The ARGUMENTS block at the bottom
of this prompt is written by the invoking assistant, NOT by the user. It
may contain the assistant's own analysis, assumptions, or field-level
details that the user never stated. When determining what the user
"already said", look ONLY at the actual user messages in the conversation
history — never treat ARGUMENTS as a substitute for user input. In
particular, do NOT skip asking about sub-DTO shape just because ARGUMENTS
describes one.
Step 0 is mental, not a tool call. Do not announce it to the user. Do not
write "Step 0 done". Just internalize what the user already said before
proceeding to Step 1.
Step 1 -- Gather minimal project context (automatic, no questions)
Call only the MCP tools whose result is actually consumed by a later
step. Do not pre-fetch "in case we need it" — every variable here must
have a concrete downstream user.
Tool
Variable
Used for
get_project_summary
language, jdkVersion, moduleName
language → variant selection (Step 4) and reference file (java vs kotlin); jdkVersion → canUseRecords = jdkVersion >= 16; moduleName → multi-module disambiguation + parameter for list_module_dependencies
springBootVersion / bootMajor — no branching depends on it
buildFile — DTO generation does not edit the build file (no
dependencies to add); a DTO needs only language constructs
mainPackage — the DTO's package is derived from the entity's FQN,
not from the project root
list_application_properties_files / propsFile — DTO writes nothing
to application.properties
list_all_domain_entities — needed only if the user did not name an
entity in their prompt. Defer to Step 2 as a lazy fallback.
get_entity_details / list_entity_dtos — depend on knowing the
entity, which happens in Step 2. Defer to Step 2.
Derived variables (all from presentDeps and get_project_summary):
hasLombok = presentDeps contains lombok
hasJackson = presentDeps contains jackson-databind or jackson-core
hasValidation = presentDeps contains hibernate-validator or jakarta.validation-api or spring-boot-starter-validation
canUseRecords = language == JAVA AND jdkVersion >= 16
If multi-module project (multiple modules in get_project_summary):
Ask which module to use. Then re-call list_module_dependencies for
that module.
Step 2 -- Entity selection
By Step 0 you should already know the entity if the user mentioned it.
Most common case: the user wrote "create DTO for Vet" → entity is
Vet, skip the question, go straight to the parallel fetch below.
Lazy fallback — only when entity is unknown: call
list_all_domain_entities(moduleName) → entities, then ask via
AskUserQuestion (options = entity names from the list, max 4; if more
than 4 entities, use the 4 most likely candidates based on context and
add a note that the user can type a different name via "Other").
This is the only place list_all_domain_entities should be called. If
the user named the entity in their prompt, do NOT call it.
After the entity FQN is known, call (in parallel):
Tool
Variable
Used for
get_entity_details(entityFqn)
entityDetails
Step 3 attribute selection, association analysis, validation inheritance, generation order in every variant reference
list_entity_dtos(entityFqn) for the parent entity is NOT called
here — it has no downstream consumer. Sub-entity calls
(list_entity_dtos(subEntityFqn)) are still needed for EXIST_CLASS
detection in references/sub-dto.md, but they are lazy and per-association,
fired only when the user is offered the EXIST_CLASS option. See
references/sub-dto.md for the exact place.
DTO name collision is handled by a different lazy call —
list_existing_classes(package) — fired right before generation in
Step 6 (see anti-hallucination checklist). It is not part of Step 2.
Step 3 -- Attribute selection
Default: include every scalar attribute and every association (with the
sub-DTO defaults from references/sub-dto.md). Ask only when context
signals that the user wants something narrower.
Decide from context (preferred over asking)
Use the purpose captured in Step 0 to pick a sensible default set:
Purpose signal
Default field set
"for REST", "for controller", "for API"
all scalars + all associations expanded (NEW_NESTED_CLASS for ToMany, FLAT id for ToOne) — the user wants the response shape, including related data
"projection", "summary", "list view", "for list"
scalars only, ToOne associations as Flat id, ToMany excluded
"for mapping", "for service", "DTO for storage"
all scalars + all associations expanded
"only id and name" / explicit field list
exactly what the user named, nothing else
no purpose signal
all scalars + all associations expanded (richest reasonable default)
If the chosen default matches the user's apparent intent, do not ask.
Just generate. State the choice in the one-line confirmation form
(principle 2) at most.
When to ask
Ask only if:
The user explicitly said "choose fields" / "ask about fields" / "fine-tune
settings", OR
The entity has many fields and the purpose signal is ambiguous AND the
user did not say "use defaults".
When asking, use AskUserQuestion with multiSelect: true:
Question
Header
Options (first = recommended)
Which fields to include in DTO {Entity}Dto?
Fields
All fields + associations (Recommended) / Scalars only / Only id and name / Specify manually
For each association included, apply the sub-DTO defaults from
references/sub-dto.md. Do NOT ask per-association unless the user
explicitly requested fine-grained control.
Step 4 -- Variant selection
Apply the Decision-making principle above. The variant is almost always
derivable from context — explicit asking should be the exception, not the
default.
If language=KOTLIN: route to references/kotlin.md. No question.
If language=JAVA: decide as follows.
Context
Action
Variant
hasLombok = true AND user prompt explicitly mentions Lombok
decide silently
references/java-lombok.md
canUseRecords = true AND hasLombok = false AND user did not ask for mutability/setters/Lombok
decide silently, mention in the one-line confirmation from principle 2
references/java-record.md
canUseRecords = false AND hasLombok = false
decide silently
references/java-plain.md
hasLombok = true AND canUseRecords = true AND user gave no signal
use the one-line confirmation form (principle 2): "Will create as Java record (JDK ≥ 16, no Lombok). Alternatives: plain class, Lombok. OK?"
depends on answer
User explicitly said "plain class" / "mutable" / "with setters"
decide silently
references/java-plain.md
User explicitly said "record"
decide silently
references/java-record.md
User explicitly said "Lombok"
decide silently (only if hasLombok = true; otherwise warn and fall back)
references/java-lombok.md
Only fall back to the full numbered question when none of the rows
above matches AND the user has not said "use defaults". Even then, prefer the
"all variants with default marked" format from principle 3 over an
iterative question.
Map answer to variant:
plain → references/java-plain.md
record → references/java-record.md
Lombok → references/java-lombok.md
Step 5 -- Variant-specific questions
Follow the variant-specific questions from the selected reference file.
Only ask if user did NOT say "all defaults".
Follow the Generation Order from the selected reference file.
For each step:
If skeleton (new file):
Read the skeleton .md from examples/_skeletons/
Apply variable substitutions
Use Write tool to create the file
If fragment:
Read the fragment .md from examples/_fragments/
Read the Insert Point to know WHERE to insert
Use Edit tool to insert code at the specified point
Apply variable substitutions
Variable substitution rules:
{packageName} -> from entity package or user choice
{className} -> from user or default {EntityName}Dto
Field-level variables -> from entity details
NEVER substitute anything not listed in Variables
NEVER add imports, methods, or code not in the example
FQN handling (CRITICAL): examples contain FQNs (e.g. java.util.Objects,
java.util.List, jakarta.validation.constraints.NotNull). When writing the
final file, you MUST:
Replace every FQN in the body of the class with its short name
(e.g. java.util.Objects.hash(...) -> Objects.hash(...),
java.util.List<Integer> -> List<Integer>,
@jakarta.validation.constraints.NotNull -> @NotNull).
Collect every FQN you shortened and emit a corresponding import line
right after the package statement, sorted, no duplicates.
Types from java.lang (String, Integer, Object, ...) must NOT be
imported and must appear as short names.
Classes from the same package as the DTO must NOT be imported.
Javadoc {@link ...} references — UNIFORM: Generate short name + import in {@link …} for every shape:
top-level Java class, top-level Java record, nested static class,
nested record, and separate-file sub-DTO (NEW_CLASS). There is no
asymmetry. Always shorten the entity reference and always add the
corresponding import line (unless the entity is in the same
package).
Group imports in two blocks separated by ONE blank line:
Block 1 — all third-party / project imports together:
jakarta.*, com.fasterxml.*, org.springframework.*,
org.hibernate.*, project packages, etc. (alphabetical inside the
block).
(blank line)
Block 2 — java.* and javax.* (alphabetical).
Do NOT split block 1 into per-package sub-blocks.
The final file must contain short names in the body (including every
Javadoc {@link …}) and a clean, grouped import block at the top.
For sub-DTOs (subDtoType=NEW_CLASS): create a separate file by repeating Steps 6.1-6.4 recursively for the sub-entity.
For nested classes (subDtoType=NEW_NESTED_CLASS): add inner class to the parent DTO file, then fill it following the same fragment rules.
Nested in a record parent — MANDATORY: when the parent DTO is a Java
record, every NEW_NESTED_CLASS association MUST be emitted as a nested
public record inside the parent record's body. The skill MUST NOT
silently fall back to NEW_CLASS (separate file) just because the
record-form fragment looks shorter. The full procedure is in
references/java-record.md Step 6 and
examples/_fragments/nested-class/java/nested-class.md ("Java record"
variant). If those instructions seem ambiguous to you, that is a bug in
the skill — fix the docs, do NOT work around it by changing the
subDtoType.
Step 7 -- Mapper (automatic when conversion is needed)
Decide whether a mapper is needed based on context, then act:
Signal
Action
User said "only DTO" / "no mapper" / "without mapper"
Skip Step 7 entirely. Do NOT mention the mapper.
User explicitly asked for a mapper ("and mapper", "with mapper", "create mapper too")
Delegate to mapper-creator immediately.
From context it is clear that entity↔DTO conversion will happen (user asked to replace entity with DTO in a controller/service/endpoint, user asked to convert/map/transform, DTO is for REST API, etc.)
Delegate to mapper-creator immediately. The conversion is inevitable — creating the DTO without a mapper would force manual inline mapping code, which is never acceptable.
Context is silent — no signal about how the DTO will be used
Skip Step 7. Do not mention the mapper.
CRITICAL: Never write manual mapping code (inline toDto/fromDto methods in controllers, services, or anywhere else). If conversion is needed, always delegate to mapper-creator. That skill decides the implementation strategy (MapStruct, Custom mapper, adding dependencies) — this skill just delegates.
Never ask AskUserQuestion for the mapper. If delegating, invoke the
mapper-creator skill with the DTO and entity information directly —
do not ask the user to confirm the delegation.
Indentation
The skill MUST detect the project's indentation style — never hardcode tabs
or spaces. Detection order:
.editorconfig at the project root (or any parent of the target
file's directory). For Java files, look up the [*.java] or [*]
section and read indent_style (tab or space) and indent_size /
tab_width.
Sample existing Java files in the same package (or the nearest
ancestor package that contains Java files). Detect whether the leading
whitespace on indented lines uses \t or spaces, and how many.
Default to 4-space if neither source is conclusive. (Tabs are also
acceptable as a default if the developer explicitly prefers them, but
the skill must never silently assume one over the other.)
Whatever style is chosen, apply it uniformly to every line of every
generated fragment (fields, constructors, getters/setters, equals/hashCode,
toString, nested classes/records). Never mix tabs and spaces inside the
same file.
Per-field options
The skill must support the following per-field controls:
Field rename (fieldNameOverride): the DTO field name can differ from
the entity attribute name. Mapper generation still maps it from the
original attribute.
Add validations (extraValidations): the user can add jakarta /
hibernate-validator constraints on top of the ones inherited from the
entity. The list of allowed constraints depends on the field type — see
references/validation.md.
Remove inherited validations (removedValidations): the user can drop
any constraint that came from the entity field.
Edit annotation parameters (message, min, max, regexp, …): all
parameters of every constraint are editable.
These options never appear unless the user explicitly asks for "fine-tune
field settings", "per-field validation" or similar. By default the skill
just inherits everything from the entity.
Anti-hallucination checklist
Before writing ANY code, verify:
The code comes from an examples/ file (cite which one)
Only declared variables were substituted
No framework API calls were added "from knowledge"
Import list matches the example exactly
Method signatures match the example exactly
No comments or convenience methods were added
FQNs from examples are shortened in the body AND corresponding import lines were added after package
Every Javadoc shape — top-level class, top-level record, nested static class, nested record, separate-file sub-DTO — uses short name {@link Pet} AND adds a matching import (unless the entity is in the same package). Uniform rule, no asymmetry.
If a sub-DTO name (separate file or nested) would collide with an existing class in the target package, auto-suffix with a number (e.g. PetDto1). The skill must do the same — call list_existing_classes(package) before generating, and append 1, 2, … until the name is free.
When generating a Java record, the inner class for any NEW_NESTED_CLASS association is also a record (not a static class). All component validators are inlined onto the record component parameters (e.g. @NotBlank String firstName), not on separate field declarations.
When isJavaRecord = true, the skill MUST NOT emit equals(), hashCode(), toString(), mutable setters, or fluent setters — records auto-generate these and these options should not be available for record DTOs.
Class-level Javadoc is multi-line (/**\n * DTO for {@link …}\n */), never collapsed to one line.
Getters and setters are multi-line (signature line, indented body, closing brace), never one-liners.
In mutable=true && fluentSetters=false mode, getters and setters are interleaved (getX, setX, getY, setY, …), not grouped.
In mutable=true mode, both the no-args constructor and the all-args constructor are emitted.
The skill does NOT offer "Only ID" as a separate option — this option does not exist (neither for ToOne nor for ToMany). The "association id only" effect is produced by Flat with only the sub-entity id checked, and the skill must implement it that way.
For collection associations (List<X>, Set<X>), Flat is offered and produces composite plural fields (Set<Integer> specialtyIds, List<Integer> petIds), provided the skill auto-checks the sub-entity scalars.
Back-reference @ManyToOne fields are filtered out of the attribute list (e.g. Pet.owner is not offered when creating PetDto).
Imports are grouped with a blank line between jakarta.* / com.* / org.* / java.* blocks.
Indentation matches the project's detected style (.editorconfig first, then sampling existing files in the same package, then 4-space default). Never hardcode tabs or spaces. Apply uniformly across every fragment in the file.
@JsonIgnoreProperties is NOT added for Kotlin (Java-only feature)
Validation annotations use @field: prefix in Kotlin
Java types are converted to Kotlin types for Kotlin DTOs
