Conversions and type checks

Convert a numeric string to int and verify the resulting type.

General CELRuns hereDocumented

What will I learn?

You can use an explicit conversion and understand that invalid input produces an error.

Where will I try it?

Directly below, in the browser playground.

What do I do?

Run both modes, compare where their values come from, then complete the task.

Try CEL · browser pilot

Try both ways to supply values

Define local values inside one CEL expression, or provide variables as JSON input. Everything runs in your browser.

CEL pilot subset

One self-contained CEL expressioncel.bind() gives a local name to a value and returns the result of the final expression.

CEL expression

cel.bind()cel.bind() is an optional official extension. It is not part of the core CEL language and may not be enabled by every host application.

Tip: press Ctrl/⌘ + Enter to run.

Result

Press Run CEL to evaluate the active example.

Pilot scope: literals, explicit conversions, local cel.bind() variables, JSON variables, lists, maps, presence, collection macros, core string checks, time values, arithmetic, comparisons, logic, and the conditional operator.

What you will do

You will run the prepared expression in the playground above, change one input at a time, and explain the result. Start in CEL only, then repeat the same rule in CEL + JSON.

How it works

Conversion functions make a type change visible. int(rawScore) reads a valid numeric string and returns an integer; type(...) returns the CEL type value. Conversion is not validation magic: int("eighty-six") is invalid and evaluation returns an error.

Read the prepared example

The CEL + JSON rule is:

type(int(rawScore)) == int && int(rawScore) >= 80

Its input is:

{
  "rawScore": "86"
}

The CEL only tab contains the values and the rule in one expression. The enabled cel.bind() extension keeps each name local to its final argument.

Evaluation step by step

int("86") produces the integer 86.
type(86) == int is true.
86 >= 80 is also true, so the final result is true.

Your task

Run the example.
Change rawScore to "79" and run again.
Change it to "high" and read the error before restoring it.

Expected observation: "79" returns false; "high" cannot be converted to int.

Common mistake

Repeated conversion is readable in a short demonstration but a host should normally provide correctly typed data. Use cel.bind() only when its extension is enabled.

Show the explanation

No. Invalid conversion is an evaluation error.

Knowledge check

Does int(rawScore) return 0 when the string is invalid?

Key takeaway

Convert explicitly and handle invalid source data as an error, not as an invented fallback value.

Sources

CEL-DEV — official CEL overview.
CEL-LANG — official CEL language definition.
CEL-GO-BIND — official documentation for the optional cel.bind() extension used by the self-contained tab.