Storing Double.POSITIVE_INFINITY in MySQL (EJB entity/JBoss) - mysql

Question

I have the following simple JPA entity:
#Entity
#Table( name = myentity_table )
public class MyEntity {
private double a;
private double b;
//(...)
}
a and b may be set to Double.POSITIVE_INFINITY. When I try to store entity with double set to +INF into database (MySQL) using standard entity manager I get exception:
java.sql.SQLException: 'Infinity' is not a valid numeric or approximate numeric value
As far as I know MySQL may not support NaN/-INF/+INF numbers. Is there any way to store this entity without writing HQL queries and translating +INF into null (or max double) ? Ideally, I'd like to do it via entity manager as usual.
Thanks in advance.

Answer 1

Entity life-cycle callback methods #PrePersist, #PreUpdate can be used here to verify the field value NAN/-INF/+INF etc & then setting the default value accordingly.
//--
#PrePersist
#PreUpdate
private void resetField() {
if(field == Double.POSITIVE_INFINITY)
field = somePredefinedValue;
}
//--

Answer 2

MySQL doesn't seem to support "infinity". This article writes that:
Storing and retrieving negative infinity in a MySQL database is accomplished by inserting an arbitrarily large negative number.
Same goes for positive. Other resources also use 1e500.
Instead of using infinity, I would suggest that you use Float.MAX_VALUE and Float.MIN_VALUE (or Double equivalents)
If you can't do this in your code when setting the values, do it in a #PrePersist as already suggested.

Answer 3

I managed this problem by adding a varchar column to store the text representation of Float.NaN, Float.POSITIVE_INFINITY and Float.NEGATIVE_INFINITY while the original column will store NULL.
Then I use the setter and the getter to do manage those two columns.
In my #Entity class
/** The value I persist. See it is a Float; */
#Column(name = "VALUE")
private Float value;
/** the 'value complement' that does the trick. */
#Column(name = "VALUE_COMPLEMENT") // You can see I've added a new column in my table (it is a varchar)
private String valueComplement;
/**
* value getter.
* If my value is null, it could mean that it is a NaN or +/- infinity.
* Then let's check the complement.
*/
public Float getValue() {
if (value == null) {
try {
return Float.parseFloat(this.valueComplement);
} catch (NumberFormatException e) {
return null;
}
} else {
return value;
}
}
/**
* value setter
* If the given value is a NaN or Inf, set this.value to null
* and this.complement to the string representation of NaN or +/- Inf.
*/
public void setValue(Float value) {
if (value != null && (value.isNaN() || value.isInfinite())) {
this.valueComplement = value.toString();
this.value = null;
} else {
this.value = value;
}
}
Result :
| ID | LABEL | VALUE | VALUE_COMPLEMENT |
| -- | --------------------- | ----- | ---------------- |
| 1 | PI | 3.14 | NULL |
| 2 | gravity acceleration | 9.81 | NULL |
| 3 | sqare root of -1 | NULL | NaN |
| 4 | log of 0 | NULL | -Infinity |