Ignore `@Transient` properties in constructors

[sunny-chung]

This is a feature request. Currently querying an entity like this would fail:

@Table(name = "chat__channel")
data class ChatChannel(
    val name: String,
    @Transient val creationRequestId: String? = null
) : BaseEntity()

with exception:

java.lang.IllegalStateException: Required property creationRequestId not found for class com.example.entity.ChatChannel
    at org.springframework.data.mapping.PersistentEntity.getRequiredPersistentProperty(PersistentEntity.java:190) ~[spring-data-commons-3.1.2.jar!/:3.1.2]
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
    *__checkpoint ⇢ Handler com.example.api.ChannelApi#list(String, Continuation) [DispatcherHandler]
Original Stack Trace:
        at org.springframework.data.mapping.PersistentEntity.getRequiredPersistentProperty(PersistentEntity.java:190) ~[spring-data-commons-3.1.2.jar!/:3.1.2]
        at org.springframework.data.r2dbc.convert.MappingR2dbcConverter$RowParameterValueProvider.getParameterValue(MappingR2dbcConverter.java:715) ~[spring-data-r2dbc-3.1.2.jar!/:3.1.2]
        at org.springframework.data.mapping.model.SpELExpressionParameterValueProvider.getParameterValue(SpELExpressionParameterValueProvider.java:49) ~[spring-data-commons-3.1.2.jar!/:3.1.2]
        at org.springframework.data.relational.core.conversion.BasicRelationalConverter$ConvertingParameterValueProvider.getParameterValue(BasicRelationalConverter.java:298) ~[spring-data-relational-3.1.2.jar!/:3.1.2]
        at org.springframework.data.mapping.model.KotlinClassGeneratingEntityInstantiator$DefaultingKotlinClassInstantiatorAdapter.extractInvocationArguments(KotlinClassGeneratingEntityInstantiator.java:222) ~[spring-data-commons-3.1.2.jar!/:3.1.2]
        at org.springframework.data.mapping.model.KotlinClassGeneratingEntityInstantiator$DefaultingKotlinClassInstantiatorAdapter.createInstance(KotlinClassGeneratingEntityInstantiator.java:196) ~[spring-data-commons-3.1.2.jar!/:3.1.2]
        at org.springframework.data.mapping.model.ClassGeneratingEntityInstantiator.createInstance(ClassGeneratingEntityInstantiator.java:98) ~[spring-data-commons-3.1.2.jar!/:3.1.2]
        at org.springframework.data.relational.core.conversion.BasicRelationalConverter.createInstance(BasicRelationalConverter.java:136) ~[spring-data-relational-3.1.2.jar!/:3.1.2]
        at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.createInstance(MappingR2dbcConverter.java:328) ~[spring-data-r2dbc-3.1.2.jar!/:3.1.2]
        at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.read(MappingR2dbcConverter.java:120) ~[spring-data-r2dbc-3.1.2.jar!/:3.1.2]
        at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.read(MappingR2dbcConverter.java:115) ~[spring-data-r2dbc-3.1.2.jar!/:3.1.2]
        at org.springframework.data.r2dbc.convert.EntityRowMapper.apply(EntityRowMapper.java:42) ~[spring-data-r2dbc-3.1.2.jar!/:3.1.2]
        at org.springframework.data.r2dbc.convert.EntityRowMapper.apply(EntityRowMapper.java:29) ~[spring-data-r2dbc-3.1.2.jar!/:3.1.2]
        at io.asyncer.r2dbc.mysql.MySqlResult.lambda$map$1(MySqlResult.java:94) ~[r2dbc-mysql-1.0.2.jar!/:1.0.2]

...

Although there are many workarounds, it would be better if fields marked @Transient and have a default value in the constructor could be "ignored", so that we do not have to add another constructor to handle this use case.

[mp911de]

Constructor arguments map to properties and @Transient is applied from the property declaration. Let me take your request to the team.

[mp911de]

We consider adding support for @Transient properties in constructors. Record components could also be annotated with the @Transient annotation to allow record construction. While this can be useful, we recommend using the @Value annotation to use SpEL expressions to determine a useful value.