Input Validation

Validates input data and returns appropriate error responses.

Example 045 of the basic Soma programs: a small, commented program that teaches one thing. Every output below was printed by soma 3.2.4 when this page was built.

How it is built

The cell Validation has no face and no memory. Handlers: run (line 14) and validate (line 30).

Generated from soma describe on this file.

The source

045_validation.cell

// ============================================================================
// 045 — Input Validation
// ============================================================================
// Validates input data and returns appropriate error responses.
//
// Run:   soma run 045_validation.cell run
// Expect:
//   Valid input: {"ok": true, "name": "Alice", "age": 25}
//   Empty name: {"error": "name is required"}
//   Bad age: {"error": "age must be between 0 and 150"}

cell Validation {

    on run() {
        // Test valid input
        let r1 = validate("Alice", 25)
        print("Valid input: {r1}")

        // Test empty name
        let r2 = validate("", 25)
        print("Empty name: {r2}")

        // Test invalid age
        let r3 = validate("Bob", -5)
        print("Bad age: {r3}")

        return "done"
    }

    on validate(name: String, age: Int) {
        // Check name is not empty
        if name == "" {
            return map("error", "name is required")
        }

        // Check name length
        let name_len = len(name)
        if name_len > 100 {
            return map("error", "name too long")
        }

        // Check age range
        if age < 0 {
            return map("error", "age must be between 0 and 150")
        }
        if age > 150 {
            return map("error", "age must be between 0 and 150")
        }

        return map("ok", true, "name", name, "age", age)
    }
}

What the toolchain says

$ soma check 045_validation.cell
✓ All checks passed.

$ soma run 045_validation.cell run
Valid input: {"ok": true, "name": "Alice", "age": 25}
Empty name: {"error": "name is required"}
Bad age: {"error": "age must be between 0 and 150"}
done