windmill-labs/windmill · error

Unknown type `{s}`

Error message

Unknown type `{s}`

What it means

The Java parser maps type_identifier nodes (wrapper/reference types) to Windmill internal types via an allowlist (String, Integer, Long, Float, Double, Boolean, Character, Object). Any other type name hits the catch-all `Ok(s) => bail!("Unknown type \`{s}\`")`, meaning the script's signature uses a Java type the parser cannot translate to a Windmill Typ.

Source

Thrown at backend/parsers/windmill-parser-java/src/lib.rs:111

}

fn find_typ<'a>(typ_node: Node<'a>, code: &str) -> anyhow::Result<(Typ, Option<Value>)> {
    let null = Some(serde_json::Value::Null);
    let res = match typ_node.kind() {
        #[rustfmt::skip]
        "type_identifier" => {
            match typ_node.utf8_text(code.as_bytes()) {
                Ok("String")      => (Typ::Str(None), null),
                Ok("Byte")        => (Typ::Bytes, null),
                Ok("Short")       => (Typ::Int, null),
                Ok("Integer")     => (Typ::Int, null),
                Ok("Long")        => (Typ::Int, null),
                Ok("Float")       => (Typ::Float, null),
                Ok("Double")      => (Typ::Float, null),
                Ok("Boolean")     => (Typ::Bool, null),
                Ok("Character")   => (Typ::Str(None), null),
                Ok("Object")      => (Typ::Object(ObjectType::new(None, Some(vec![]))),null), // TODO: Complete the object type
                Ok(s)       => bail!("Unknown type `{s}`"),
                Err(e) => bail!("Error getting type name: {}", e),
            }
        }
        #[rustfmt::skip]
        "integral_type" => {
            match typ_node.utf8_text(code.as_bytes()) {
                Ok("byte")   => (Typ::Bytes, None),
                Ok("short")  => (Typ::Int, None),
                Ok("int")    => (Typ::Int, None),
                Ok("long")   => (Typ::Int, None),
                Ok("char")   => (Typ::Str(None), None),
                Ok(s)  => bail!("Unknown type `{s}`"),
                Err(e) => bail!("Error getting type name: {}", e),
            }
        }
        "floating_point_type" => {
            match typ_node.utf8_text(code.as_bytes()) {
                Ok("float") => (Typ::Float, None),

View on GitHub (pinned to e474e8803c)

Solutions

1. Change the script's parameter/return types to allowlisted ones: use String, Integer/Long, Float/Double, Boolean, Character, or Object.
2. Type collections as `Object` (the parser maps Object to a generic ObjectType) and document the shape.
3. If you own the parser, extend the match arms in backend/parsers/windmill-parser-java/src/lib.rs to map more type names (search ADD_NEW_LANG-style lists) or fall back to Typ::Object instead of bailing.
4. Read the exact `{s}` in the error to identify which offending type name to replace.

Example fix

// before (Java script signature)
public static List<String> main(String input) { ... }
// after
public static Object main(String input) { ... } // List returned as Object

# validate Java script signatures before pushing
ALLOWED = {"String","Integer","Long","Float","Double","Boolean","Character","Object"}
import re
for t in re.findall(r"(?:public|private|protected)[^({]*\(([^)]*)\)", java_src):
    for p in t.split(","):
        typ = p.strip().split()[-2] if len(p.split()) >= 2 else None
        if typ and typ not in ALLOWED:
            raise ValueError(f"parameter type {typ} not supported by the Java parser; use Object")

function isParserSupportedJavaType(t: string): boolean {
  return ["String","Integer","Long","Float","Double","Boolean","Character","Object"].includes(t);
}

// when calling the parser programmatically
match parse_java_typ(...) {
  Err(e) if e.to_string().starts_with("Unknown type") => {
    // fall back to Typ::Object or surface a friendly UI message
  }
  other => other?,
}

When it happens

Trigger: Parsing a Java script whose parameters or return type reference a class type not in the allowlist — e.g. custom classes, BigDecimal, List<String>, Map<...>, or a fully-qualified type — passed to find_typ on a `type_identifier` node.

Common situations: Hub or user Java scripts typed with collection interfaces (List, ArrayList), boxed numerics beyond the allowlist (BigInteger, Short), or user-defined POJOs; windmill sync / script validation against the workspace.

Related errors

• Failed to parse code
• Failed to find inner type of array type
• Internal error: Failed to get child by field name 'type'
• Aborted from C
• vsnprintf is not supported

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/686c45cb5a7f6d4f. Report an issue: GitHub.