Cannot find setter for field - using Kotlin with Room database

I'm integrating with the Room persistence library. I have a data class in Kotlin like:

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

The `@Entity` and `@PrimaryKey` annotations are for the Room library. When I try to build, it is failing with error:

Error:Cannot find setter for field.
Error:Execution failed for task ':app:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

I also tried providing a default constructor:

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

But this doesn't work as well. A thing to note is that it works if I convert this Kotlin class into a Java class with getters and setters. Any help is appreciated!

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:

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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,
)

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

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> 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][1]


[1]:

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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

According to

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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`:

[![enter image description here][1]][1]

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

[1]:

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

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

1. You should update to AndroidX room [current version][1].
2. Check for the related [issue here][2] it is marked as **Won't Fix**
3. Now they have release a fix related to the issue with [version 2.0.0-beta01][3]
4. 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


[1]:

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[2]:

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[3]:

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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;
}

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`.