找不到现场使用科特林与房间数据库塞特

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最佳答案

Since your fields are marked with val, they are effectively final and don't have setter fields.

Try switching out the val with var. You might also need to initialize the fields.

@Entity(tableName = "story")
data class Story (
@PrimaryKey var id: Long? = null,
var by: String = "",
var descendants: Int = 0,
var score: Int = 0,
var time: Long = 0L,
var title: String = "",
var type: String = "",
var url: String = ""
)

EDIT

The above solution is a general fix for this error in Kotlin when using Kotlin with other Java libraries like Hibernate where i've seen this as well. If you want to keep immutability with Room, see some of the other answers which may be more specific to your case.

In some cases immutability with Java libraries is simply not working at all and while making sad developer noises, you have to switch that val for a var unfortunately.

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Another cause of this may be the naming of the field. If you use any of the pre-defined keywords, you will get the same error. For instance, you can not name your column "is_active".

Reference: http://www.sqlite.org/lang_keywords.html

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Had this error in Java.

You cannot have a column starting with is or is_ in Java.

Try renaming the column.

Another solution:

You either have to pass the field in the constructor and initialize it with the constructor argument, or create a setter for it.

Example:

public MyEntity(String name, ...) {
this.name = name;
...
}


public void setName(String name) {
this.name = name;
}

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Hey I don't know if everyone know or not, but you can not have column which is starting from is into Room. For example you can't have like this

   @Entity(tableName = "user")
data class User (
@PrimaryKey var id: Long? = null,
var userName: String = "",
var isConnectedToFB: Boolean = false,
)

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There is an issue in room db library java code generation.

I was using optional field isFavorite. It gives me same error then I change my field name to favorite then compiled.

before var isFavorite: Int? = 0, after changing working fine var favorite: Int? = 0, Thanks

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According to https://stackoverflow.com/a/46753804/2914140 if you have an autogenerated primary key, you should write so:

@Entity(tableName = "story")
data class Story (
val by: String,
val descendants: Int,
val score: Int,
val time: Long,
val title: String,
val type: String,
val url: String
)  {
@PrimaryKey(autoGenerate = true)
var id: Int = 0
}

Note that @PrimaryKey is written inside the class body and contains modifier var.

If you later want to update a row in a database with different parameters, use these lines:

val newStory = story.copy(by = "new author", title = "new title") // Cannot use "id" in object cloning
newStory.id = story.id
dao.update(newStory)

UPDATE

I still don't use AndroidX, and Room is 'android.arch.persistence.room:runtime:1.1.1'.

You can extend this class from Serializable. But if you want to extend it from Parcelable, you will get a warning (over id variable): Property would not be serialized inro a 'Parcel'. Add '@IgnoredOnParcel' annotation to remove this warning:

Then I moved an id from the body to the constructor. In Kotlin I use @Parcelize to create Parcelable classes:

@Parcelize
@Entity(tableName = "story")
data class Story (
@PrimaryKey(autoGenerate = true)
var id: Int = 0,


val by: String,
val descendants: Int,
val score: Int,
val time: Long,
val title: String,
val type: String,
val url: String
) : Parcelable

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This is a bug and is fixed in Room 2.1.0-alpha01

https://developer.android.com/jetpack/docs/release-notes#october_8_2018

Bug Fixes

Room will now properly use Kotlin’s primary constructor in data classes avoiding the need to declare the fields as vars. b/105769985

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Just an update if somebody comes across this thread in 2019, after spending hours digging online on why this should work, but it doesn't.

Using val works as expected if you are using the AndroidX version ( androidx.room:room-<any>:2.*) but it doesn't when using the old android.arch.persistence.room:<any>:1.1.1 and it seems that version 2.* wasn't released on this latter repo.

Edit: typos

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If you want the val immutability available for your entity, it is possible.

You should update to AndroidX room current version.
Check for the related issue here it is marked as Won't Fix
Now they have release a fix related to the issue with version 2.0.0-beta01
Now you can use immutable val with default value e.g:

@Entity("tbl_abc")
data class Abc(
@PrimaryKey
val id: Int = 0,
val isFavourite: Boolean = false
)

Previously, the above snippet will throw an error of Cannot find setter for field. Changing into var is a great workaround, but I prefer for the entity class to be immutable from outside invocation

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You can now start your field with is but you can't have a number next to the is like : is2FooSelected, you have to rename to isTwoFooSelected.

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I've found that another cause of this compilation error can be due to the use of the Room's @Ignore annotation on fields of your entity data class:

@Entity(tableName = "foo")
data class Foo(


// Okay
@PrimaryKey
val id: String,


// Okay
val bar: String,


// Annotation causes compilation error, all fields of data class report
// the "Cannot find setter for field" error when Ignore is present
@Ignore
val causeserror: String
)

The same error also seems to happens when using the @Transient annotation.

I've noticed this issue using version 2.2.2 of Room:

// build.gradle file
dependencies {
...
kapt "androidx.room:room-compiler:2.2.2"
...
}

Hope that helps someone!

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Just use var instead of val and if you are using private keyword, make it public.

@Entity(tableName = "story")
data class Story (
@PrimaryKey val id: Long,
var by: String,
var descendants: Int,
var score: Int,
var time: Long,
var title: String,
var type: String,
var url: String
)

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This error will be thrown if your column starts with Is:

@ColumnInfo(name = "IsHandicapLeague")
@NonNull
var isHandicapLeague: String = "Y"

Add a default set() function to eliminate

fun setIsHandicapLeague(flag:String) {
isHandicapLeague = flag
}

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If you have @Ignore field in the data class constructor you need to move it to class body like this:

@Entity(primaryKeys = ["id"])
data class User(
@field:SerializedName("id")
val id: Int,


@field:SerializedName("name")
val name: String,
    

@field:SerializedName("age")
val age: Int
) {
@Ignore
val testme: String?
}

All kudos go to marianperca on GitHub: https://github.com/android/architecture-components-samples/issues/421#issuecomment-442763610

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You can try to rename id variable to another name. It worked for me ;

var id: Long? = null

to

var workerId: Long? = null

If you have to name as id and you are using retrofit, then you may need to add SerializedName("id")

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Just make the variables mutable, change val into var for Kotlin, Or private into public for Java

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It seems like Room and Kotlin versions need to be matched. I have same issue with Room 2.3.0 and Kotlin 1.6.10 but it's ok with Kotlin 1.5.20. It looks ok after I updated Room to 2.4.2. https://youtrack.jetbrains.com/issue/KT-45883

Also there is a possible solution to use @JvmOverloads constructor for better Java compability.

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Updating Room library to the latest version 2.4.2 solve the issue

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I think that the variable we wrote as id is getting mixed up with the id in the system. Therefore, when I define it as uuid, my error is resolved. I think it will be solved too. Also, try using var instead of val.

@PrimaryKey(autoGenerate = true) var uuid:Int=0

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The correct way to fix this issue would be simply updating to Room v2.4.3 or higher.

Workaround

If you're running on an older version of Room, one that uses an old version of the kotlinx-metadata-jvm library which doesn't understand 1.5.x metadata, a simple workaround would be adding the following line to your build.gradle:

kapt "org.jetbrains.kotlinx:kotlinx-metadata-jvm:0.5.0"

Source: https://youtrack.jetbrains.com/issue/KT-45883/KAPT-Cannot-find-setter-for-field-compiling-projects-with-Room-db-breaks-using-150-M2