# Quantity

Used to record a single non-negative integer value or 0. For example, the width of the display in pixels.

IMPORTANT If you need to count something (e.g. number of tabs open or number of times a button is pressed) prefer using the Counter metric type, which has a specific API for counting things and also takes care of resetting the count at the correct time.

## Configuration

Say you're adding a new quantity for the width of the display in pixels. First you need to add an entry for the quantity to the metrics.yaml file:

display:
width:
type: quantity
description: >
The width of the display, in pixels.
unit: pixels
...


Note that quantities have a required unit parameter, which is a free-form string for documentation purposes.

## API

import org.mozilla.yourApplication.GleanMetrics.Display

Display.width.set(width)


There are test APIs available too:

import org.mozilla.yourApplication.GleanMetrics.Display

// Was anything recorded?
assertTrue(Display.width.testHasValue())
// Does the quantity have the expected value?
assertEquals(6, Display.width.testGetValue())
// Did it record an error due to a negative value?
assertEquals(1, Display.width.testGetNumRecordedErrors(ErrorType.InvalidValue))

import org.mozilla.yourApplication.GleanMetrics.Display;

Display.INSTANCE.width.set(width);


There are test APIs available too:

import org.mozilla.yourApplication.GleanMetrics.Display;

// Was anything recorded?
assertTrue(Display.INSTANCE.width.testHasValue());
// Does the quantity have the expected value?
assertEquals(6, Display.INSTANCE.width.testGetValue());
// Did the quantity record a negative value?
assertEquals(
1, Display.INSTANCE.width.testGetNumRecordedErrors(ErrorType.InvalidValue)
);

Display.width.set(width)


There are test APIs available too:

@testable import Glean

// Was anything recorded?
XCTAssert(Display.width.testHasValue())
// Does the quantity have the expected value?
XCTAssertEqual(6, try Display.width.testGetValue())
// Did the quantity record a negative value?
XCTAssertEqual(1, Display.width.testGetNumRecordedErrors(.invalidValue))

from glean import load_metrics

metrics.display.width.set(width)


There are test APIs available too:

# Was anything recorded?
assert metrics.display.width.test_has_value()
# Does the quantity have the expected value?
assert 6 == metrics.display.width.test_get_value()
# Did the quantity record an negative value?
from glean.testing import ErrorType
assert 1 == metrics.display.width.test_get_num_recorded_errors(
ErrorType.INVALID_VALUE
)

using static Mozilla.YourApplication.GleanMetrics.Display;

Display.width.Set(width);


There are test APIs available too:

using static Mozilla.YourApplication.GleanMetrics.Display;

// Was anything recorded?
Assert.True(Display.width.TestHasValue());
// Does the counter have the expected value?
Assert.Equal(6, Display.width.TestGetValue());
// Did the counter record an negative value?
Assert.Equal(
1, Display.width.TestGetNumRecordedErrors(ErrorType.InvalidValue)
);


#![allow(unused)]
fn main() {
use glean_metrics;

display::width.set(width);
}


There are test APIs available too:


#![allow(unused)]
fn main() {
use glean_metrics;

// Was anything recorded?
assert!(display::width.test_get_value(None).is_some());
// Does it have the expected value?
assert_eq!(width, display::width.test_get_value(None).unwrap());
}


## Limits

• Quantities must be non-negative integers or 0.

## Examples

• What is the width of the display, in pixels?

## Recorded errors

• invalid_value: If a negative value is passed in.