ToDouble

This reference topic applies to FQL v4. Go to this page for the latest FQL v10 reference topics.

 
ToDouble( value )
to_double( value )
ToDouble( value )
ToDouble( value )
ToDouble( value )
ToDouble( value )

Description

The ToDouble function converts a value to a double-precision numeric value, if possible.

Attempting to convert a value to a double-precision numeric value which has no numeric representation results in an "invalid argument" error.

Host languages have varying support for double-precision numeric values. Within Fauna, double-precision numeric values are stored and operated on as 64-bit, IEEE 754, double-precision float values. The host language you use may affect how the result of ToDouble can be interpreted.

Parameters

Parameter Type Definition and Requirements

value

Any

The value to attempt to convert to a double-precision numeric value.

Returns

A double-precision numeric value.

Examples

The following query calls ToDouble multiple times to demonstrate variations on the kinds of values that ToDouble accepts:

client.query(
  [
    q.ToDouble(1234.5678),
    q.ToDouble(1234),
    q.ToDouble('123.456789'),
    q.ToDouble('0not-a-number'),
  ]
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))
[ 1234.5678, 1234, 123.456789, 0 ]
result = client.query(
  [
    q.to_double(1234.5678),
    q.to_double(1234),
    q.to_double('123.456789'),
    q.to_double('0not-a-number'),
  ]
)
print(result)
[1234.5678, 1234.0, 123.456789, 0.0]
result, err := client.Query(
	f.Arr{
		f.ToDouble(1234.5678),
		f.ToDouble(1234),
		f.ToDouble("123.456789"),
		f.ToDouble("0not-a-number"),
	})

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
[1234.5678 1234 123.456789 0]
try
{
    Value result = await client.Query(
        Arr(
            ToDouble(1234.5678),
            ToDouble(1234),
            ToDouble("123.456789"),
            ToDouble("0not-a-number")
        )
    );

    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}
Arr(DoubleV(1234.5678), DoubleV(1234), DoubleV(123.456789), DoubleV(0))
System.out.println(
    client.query(
        Arr(
            ToDouble(1234.5678),
            ToDouble(1234),
            ToDouble("123.456789"),
            ToDouble("0not-a-number")
        )
    ).get());
[1234.5678, 1234.0, 123.456789, 0.0]
[
  ToDouble(1234.5678),
  ToDouble(1234),
  ToDouble('123.456789'),
  ToDouble('0not-a-number'),
]
[ 1234.5678, 1234, 123.456789, 0 ]
Query metrics:

  •    bytesIn: 101

  •   bytesOut:  46

  • computeOps:   1

  •    readOps:   0

  •   writeOps:   0

  •  readBytes:   0

  • writeBytes:   0

  •  queryTime: 2ms

  •    retries:   0
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