Symfony – Rounded decimal in edit form Symfony2 + Doctrine2

decimaldoctrine-ormsymfony

How do I set the decimal precision and scale within the symfony2 entity? I've defined latitude in longitude fields using decimal data type in my entity like this:

/**
 * @ORM\Column(type="decimal", precision="10", scale="6", nullable=true)
 */
protected $latitude;

When persisting new object it saves decimal correctly (I can see 52.406374 in phpMyAdmin). However when displaying edit form the number is rounded to 52,406 and after updating it is stored in mysql as 52.406000. Probably something is wrong with my Doctrine configuration, but I don't know what.

Why is the latitude and longitude getting rounded?

Found a solution:

Symfony's Form component renders decimal form field as type="text". When using:

->add('latitude', 'number', array(
    'precision' => 6,
))

It is rendered properly. The thread from comment doesn't describe my problem.
I guess they have already fixed bug with 'convert to float' precision.
When I was displaying latitude in twig template it was showing proper (not rounded) value.

Best Answer

How to set the symfony decimal type precision and scale:

Set it in your entity, like this:

protected $mycolumn;
/**
* @ORM\Column(type="decimal", precision=14, scale=8, nullable=true)
*/

This sets the datatype in the MySQL database:

mycolumn decimal(14,8)

What do scale and precision mean when specifying a decimal field type in Doctrine 2?

Related Solutions

Java – How to round a number to n decimal places in Java

Use setRoundingMode, set the RoundingMode explicitly to handle your issue with the half-even round, then use the format pattern for your required output.

Example:

DecimalFormat df = new DecimalFormat("#.####");
df.setRoundingMode(RoundingMode.CEILING);
for (Number n : Arrays.asList(12, 123.12345, 0.23, 0.1, 2341234.212431324)) {
    Double d = n.doubleValue();
    System.out.println(df.format(d));
}

gives the output:

12
123.1235
0.23
0.1
2341234.2125

EDIT: The original answer does not address the accuracy of the double values. That is fine if you don't care much whether it rounds up or down. But if you want accurate rounding, then you need to take the expected accuracy of the values into account. Floating point values have a binary representation internally. That means that a value like 2.7735 does not actually have that exact value internally. It can be slightly larger or slightly smaller. If the internal value is slightly smaller, then it will not round up to 2.7740. To remedy that situation, you need to be aware of the accuracy of the values that you are working with, and add or subtract that value before rounding. For example, when you know that your values are accurate up to 6 digits, then to round half-way values up, add that accuracy to the value:

Double d = n.doubleValue() + 1e-6;

To round down, subtract the accuracy.

C# – How to display a decimal value to 2 decimal places

decimalVar.ToString("#.##"); // returns ".5" when decimalVar == 0.5m

or

decimalVar.ToString("0.##"); // returns "0.5"  when decimalVar == 0.5m

or

decimalVar.ToString("0.00"); // returns "0.50"  when decimalVar == 0.5m

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