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Q&A Json deserialization of enum, forbid int

I have a DTO that contains an enum field: @Getter @Setter static class Foo { Bar bar; } enum Bar { X, Y } When I deserialize a JSON, it allows int as values: var objectMapper ...

2 answers · posted 3mo ago by talex‭ · edited 3mo ago by hkotsubo‭

Question java json jackson

#4: Post edited by

hkotsubo‭ · 2024-09-24T19:12:46Z (3 months ago)
Minor improvements in text / added tag for Jackson library

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Json deserialization of enum, forbid int

~~I have DTO that contains `enum`:~~
~~```~~
~~@Getter~~
~~@Setter~~
~~static class Foo {~~
~~Bar bar;~~
}
~~enum Bar {~~
~~X, Y~~
}
```
~~When I deserialize json it allow to use `int` as values.~~
```
~~var objectMapper = new ObjectMapper();~~
~~Foo foo = objectMapper.readValue("""~~
~~{"bar": 1}"~~
~~""",~~
~~Foo.class~~
);
~~```~~
~~I expect error here, but get value `Bar.Y`.~~
How can I validate Json so only string values for `enum`s allowed?
~~Here id json library dependency:~~
~~```~~
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.17.1</version>
</dependency>
~~```~~

I have a DTO that contains an `enum` field:
```java
@Getter
@Setter
static class Foo {
Bar bar;
}
enum Bar {
X, Y
}
```
When I deserialize a JSON, it allows `int` as values:
```java
var objectMapper = new ObjectMapper();
Foo foo = objectMapper.readValue("""
{"bar": 1}"
""",
Foo.class
);
```
I expect an error here, but get the value `Bar.Y`.
How can I validate a JSON so only string values for `enum` are allowed?
Here's the JSON library dependency:
```xml
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.17.1</version>
</dependency>
```

java json

java json jackson

#3: Post edited by

talex‭ · 2024-09-24T13:54:49Z (3 months ago)

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I have DTO that contains `enum`:
```
@Getter
@Setter
static class Foo {
Bar bar;
}
enum Bar {
X, Y
}
```
When I deserialize json it allow to use `int` as values.
```
~~import com.fasterxml.jackson.databind.ObjectMapper;~~
~~//...~~
var objectMapper = new ObjectMapper();
Foo foo = objectMapper.readValue("""
{"bar": 1}"
""",
Foo.class
);
```
I expect error here, but get value `Bar.Y`.
~~How can I validate Json so only string values for `enum`s allowed?~~

I have DTO that contains `enum`:
```
@Getter
@Setter
static class Foo {
Bar bar;
}
enum Bar {
X, Y
}
```
When I deserialize json it allow to use `int` as values.
```
var objectMapper = new ObjectMapper();
Foo foo = objectMapper.readValue("""
{"bar": 1}"
""",
Foo.class
);
```
I expect error here, but get value `Bar.Y`.
How can I validate Json so only string values for `enum`s allowed?
Here id json library dependency:
```
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.17.1</version>
</dependency>
```

#2: Post edited by

talex‭ · 2024-09-24T13:30:31Z (3 months ago)

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I have DTO that contains `enum`:
```
@Getter
@Setter
static class Foo {
Bar bar;
}
enum Bar {
X, Y
}
```
When I deserialize json it allow to use `int` as values.
```
var objectMapper = new ObjectMapper();
Foo foo = objectMapper.readValue("""
{"bar": 1}"
""",
Foo.class
);
```
I expect error here, but get value `Bar.Y`.
How can I validate Json so only string values for `enum`s allowed?

I have DTO that contains `enum`:
```
@Getter
@Setter
static class Foo {
Bar bar;
}
enum Bar {
X, Y
}
```
When I deserialize json it allow to use `int` as values.
```
import com.fasterxml.jackson.databind.ObjectMapper;
//...
var objectMapper = new ObjectMapper();
Foo foo = objectMapper.readValue("""
{"bar": 1}"
""",
Foo.class
);
```
I expect error here, but get value `Bar.Y`.
How can I validate Json so only string values for `enum`s allowed?

#1: Initial revision by

talex‭ · 2024-09-24T13:22:03Z (3 months ago)

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Json deserialization of enum, forbid int

I have DTO that contains `enum`:

```
    @Getter
    @Setter
    static class Foo {
        Bar bar;
    }

    enum Bar {
        X, Y
    }
```

When I deserialize json it allow to use `int` as values.

```
        var objectMapper = new ObjectMapper();
        Foo foo = objectMapper.readValue("""
                {"bar": 1}"
                """,
            Foo.class
        );
```
I expect error here, but get value `Bar.Y`.

How can I validate Json so only string values for `enum`s allowed?

java json

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