{"record":{"id":"a5602b5567b5f555","repo":"DioxusLabs/dioxus","slug":"expected-an-expression","errorCode":null,"errorMessage":"Expected an expression","messagePattern":"Expected an expression","errorType":"validation","errorClass":"syn::Error","httpStatus":null,"severity":"error","filePath":"packages/rsx/src/attribute.rs","lineNumber":569,"sourceCode":"                block.span(),\n                \"Expected a single statement in the if block\",\n            ));\n        }\n\n        // either an ifmt or an expr in the block\n        let stmt = &stmts[0];\n\n        // Either it's a valid ifmt or an expression\n        match stmt {\n            syn::Stmt::Expr(exp, None) => {\n                // Try parsing the statement as an IfmtInput by passing it through tokens\n                let value: Result<HotLiteral, syn::Error> = syn::parse2(exp.to_token_stream());\n                Ok(match value {\n                    Ok(res) => Box::new(AttributeValue::AttrLiteral(res)),\n                    Err(_) => Box::new(AttributeValue::AttrExpr(PartialExpr::from_expr(exp))),\n                })\n            }\n            _ => Err(syn::Error::new(stmt.span(), \"Expected an expression\")),\n        }\n    }\n\n    fn to_tokens_with_terminated(\n        &self,\n        tokens: &mut TokenStream2,\n        terminated: bool,\n        contains_expression: bool,\n    ) {\n        let IfAttributeValue {\n            if_expr,\n            then_value,\n            else_value,\n            ..\n        } = self;\n\n        // Quote an attribute value and convert the value to a string if it is formatted\n        // We always quote formatted segments as strings inside if statements so they have a consistent type","sourceCodeStart":551,"sourceCodeEnd":587,"githubUrl":"https://github.com/DioxusLabs/dioxus/blob/24f6a829df0dfa203961a98ea4cae21c2ff27e28/packages/rsx/src/attribute.rs#L551-L587","documentation":"`parse_attribute_value_from_block` handles `attr={...}` blocks containing a single statement; this error fires when the statement is neither a formatted string literal nor a plain expression — i.e. the block's content cannot be interpreted as an attribute value. Typical cause is multiple statements or unsupported syntax inside the braces.","triggerScenarios":"Thrown at packages/rsx/src/attribute.rs:569 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Provide a valid Rust expression in the attribute value; the parser expected an expression at this position."],"exampleFix":null,"handlingStrategy":"validation","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"24f6a829df0dfa203961a98ea4cae21c2ff27e28","analyzedAt":"2026-08-23T07:10:14.078Z","contentChangedAt":"2026-08-23T07:10:14.078Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}