When building websites with AnQi CMS, we often need to flexibly handle and display data in templates. Among them,integerandfloatThese filters are very useful tools when converting values to integers or floating-point numbers.However, have you ever thought about how the system will handle when these filters receive a value that cannot be identified as a number?In other words, what default values will these filters return if the conversion operation fails?Understanding this is crucial for us to write robust and predictable template logic.
floatFilter: When non-numeric meets floating-point number conversion
floatThe main function of the filter is to attempt to convert the input value to a floating-point number.This is very useful when precise calculations or displaying decimal places are required.What if the data it receives is not a valid number format, such as a text string or a null value?
According to the document instructions of Anqi CMS, whenfloatThe filter defaults to returning when it encounters a value that cannot be processed during the conversion process0.0This means that, regardless of whether you pass a completely non-numeric string, such as{{ "foobar"|float }}or an empty valueniltype ({{ nil|float }}), the final result displayed in the template will be0.000000This floating-point number.
This design ensures that the template can maintain stable operation even in the face of irregular data, avoiding errors or interruptions on the page due to incorrect conversion. However, this also reminds us that in certain scenarios, we need to pay extra attention to distinguish this.0.0Is it an actual zero value, or a default value generated due to a conversion failure.
integerFilter: How does it behave after integer conversion fails.
WithfloatFilter: A different but similar approach,integerThe responsibility of the filter is to attempt to convert the input value to an integer. In many cases, we need to ensure that the data is presented as an integer, such as product quantity, user ID, etc. Then,integerWhat will the filter respond when it fails to convert?
The document of AnQi CMS explicitly states that whenintegerThe default return value of the filter is when it encounters a failure in conversion0This means that if you try to pass such non-numeric strings as{{ "foobar"|integer }}or a variable representing a null value{{ nothing|integer }}to it, the result will be0.
It is worth mentioning that,integerThe filter can also handle values that have already been converted to floating-point numbers. For example, if you first convertfloatto5.4to a floating-point number, thenintegerconvert to an integer, that is{{ "5.4"|float|integer }}, you will get5. Similarly,{{ "5.6"|float|integer }}Will also be obtained5This indicatesintegerThe filter performs floor division (i.e., truncating the decimal part) when processing floating-point numbers. But iffloatthe conversion has already failed and returned in the previous step0.0so thatintegerThe filter will also convert it on this basis.0.
Why is it important to understand these default return values?
MasterintegerandfloatThe default return value of the filter when the conversion fails is crucial for us to build a stable and reliable security CMS website template. This not only helps us:
- predict the behavior of the template[en]To anticipate how the template will handle exceptions when the data source is不规范 or missing, avoiding unnecessary confusion.
- [en]Write more robust logicIn designing conditional judgments in templates, you can take into account
0or0.0it can be either real data or the default value after conversion failed, thereby writing more accurate display logic. - simplifying the debugging processWhen the page displays an error, it can locate the problem faster and determine whether the issue is with the data itself or if the filter conversion failure led to the appearance of default values.
In summary, theintegerfilter returns0whilefloatthe filter returns0.0Deeply understanding these default behaviors allows us to be more skillful in the process of template development, building websites that are more user-friendly and feature-rich.
Common Questions (FAQ)
Can these filters be used for non-string types like numbers? For example, passing a Go language integer or floating-point number directly?
Yes, it can.integerandfloatThe filter is not limited to processing strings, it can also be applied to existing numeric type variables.In this case, they are more like type assertions or conversions for variables to ensure that the data is processed as the expected numeric type (integer or float).{{ 5|float }}You will get5.000000while{{ 6|float|integer }}Then you will get6This is very useful to ensure that the data has a consistent type in subsequent calculations or displays.
2. Can it be customized when the conversion fails?integerandfloatThe default return value of the filter, rather than always0or0.0?
According to the current filter document of AnQi CMS,integerandfloatthe filter itself does not provide parameters to customize the default return value when the conversion fails. They will return0or0.0However, you can achieve a similar purpose by combining other filters. For example, you can useintegerorfloata filter afterdefaultfilter. Like{{ "非数字"|integer|default:"-1" }}such a writing, it willintegerFailed conversion and return0Then, convert this0Replace it with the one you specified-1.
3.integerWhen the filter processes floating-point numbers, is it rounded up or down?
From the example in the Anqi CMS document,integerThe filter performs floor operation (or truncation of the decimal part) when converting floating-point numbers to integers.This means it will directly discard the decimal part instead of rounding.5.4Or5.6AfterfloatandintegerThe processing of the filter results in integer values that are all5.