@ConstructorResult with Enum in JPA 2.1

Question

I am not having any idea how to use Enum in @ColumnResult Type while using @ConstructorResult of @SqlResultSetMapping ``` @SqlResultSetMapping(name="DetailAndResult", classes={ @ConstructorResult(targetClass=DetailAndResult.class, columns={ @ColumnResult(name="id", type= String.class), @ColumnResult(name="runId", type=Integer.class), @ColumnResult(name="subRunId", type=Integer.class), @ColumnResult(name="transactionId", type=Integer.class), @ColumnResult(name="referenceNumber", type=String.class), @ColumnResult(name="customerName", type=String.class), @ColumnResult(name="transactionType", type=TransactionType.class), @ColumnResult(name="transactionResultStatus", type=String.class) }) } ) ``` in above configuration, name 'transactionType' is of TransactionType Enum. What is the correct way to use Enum here. if above is the correct way then I am getting this exception (If I will remove the Enum field then there is no exception) so thinking that there should be another way to use this. `…

Accepted Answer

I've also run into this problem and haven't found anything after a fairly extensive search. I've gone as far as looking at the source code, and as far as I could tell there wasn't any kind of handling for enums at all (although of course I could be missing something).

What I ended up doing was creating an alternative constructor that took in a String for the enum type, and then passed it into the enum's valueOf() method.

E.g.

change your @SqlResultSetMapping to do this:

```
@ColumnResult(name="transactionType", type=String.class),
```

And then in the constructor of your class:

```
public DetailAndResult(..., String transactionType, ...) {
    ...
    this.transactionType = TransactionType.valueOf(transactionType);
    ...
}
```

It's annoying that we have to do this, but so long as your enum is stored as a String in the db (i.e. the column on your entity is annotated with @Enumerated(EnumType.STRING)), it works.

@ConstructorResult with Enum in JPA 2.1

Solution

Problem