clockworklabs/SpacetimeDB · error · anyhow::Error

Either --out-dir or --uproject-dir is required

Error message

Either --out-dir or --uproject-dir is required

What it means

When resolving the output directory for a generate run, the CLI tries four sources in order: --out-dir, --uproject-dir, then a per-language default (default_out_dir_for_language: 'src/module_bindings' for Rust/TypeScript, 'module_bindings' for C#, and None for UnrealCpp). If all are exhausted — only possible for a language with no default, i.e. unrealcpp — the run is rejected with 'Either --out-dir or --uproject-dir is required'. Note the uproject_dir lookup flattens resolution errors with .ok(), so an unresolvable uproject-dir path is silently treated as absent.

Solutions

1. Pass --out-dir explicitly: `spacetime generate --lang unrealcpp --out-dir ./Generated`
2. Or pass --uproject-dir, which doubles as the output location for unrealcpp
3. For config-driven runs, add a resolvable `out-dir` (absolute, or relative to the spacetime.json directory) to the generate entry

Example fix

# before
spacetime generate --lang unrealcpp --bin-path module.wasm
# after
spacetime generate --lang unrealcpp --bin-path module.wasm --out-dir ~/Projects/MyGame/Plugins/SpacetimeDB/Source

# spacetime.json generate entry — after
# { "language": "unrealcpp", "bin-path": "target/wasm32-unknown-unknown/release/module.wasm",
#   "out-dir": "../MyGame/Plugins/SpacetimeDB/Source" }

# unrealcpp has NO default out dir — require one explicitly:
: "${OUT_DIR:?unrealcpp needs --out-dir or --uproject-dir}"
spacetime generate --lang unrealcpp --out-dir "$OUT_DIR" "$@"

When it happens

Trigger: `spacetime generate --lang unrealcpp` with neither --out-dir nor --uproject-dir (typical when error 345 was bypassed via config-supplied uproject-dir that failed to resolve, or when generating unrealcpp from a spacetime.json entry lacking both keys).

Common situations: Non-interactive/CI generation for unrealcpp where the operator assumed a default output folder exists; spacetime.json generate entries copied from a Rust project (which never need out-dir because of the default) and switched to unrealcpp; a relative uproject-dir in config that fails to resolve against config_dir and is dropped by .ok().flatten().

Related errors

• --unreal-module-name is required for --lang unrealcpp
• --uproject-dir is required for --lang unrealcpp
• --namespace is only supported with --lang csharp
• Unknown client language
• Unknown server language

AI-assisted analysis of clockworklabs/SpacetimeDB@eddf9f5014 (2026-08-20). Data as JSON: /api/errors/470b45023d6225e4. Report an issue: GitHub.

Appendix: source

Thrown at crates/cli/src/subcommands/generate.rs:384

                println!(
                    "Detected client language '{}' from '{}'. If this is not correct, pass --lang or add a generate target in spacetime.json.",
                    language_cli_name(detected),
                    client_project_dir.display()
                );
                detected
            }
        };

        let out_dir = command_config
            .get_resolved_path("out_dir", config_dir)?
            .or_else(|| {
                command_config
                    .get_resolved_path("uproject_dir", config_dir)
                    .ok()
                    .flatten()
            })
            .or_else(|| default_out_dir_for_language(lang).map(|p| config_dir.map(|d| d.join(&p)).unwrap_or(p)))
            .ok_or_else(|| anyhow::anyhow!("Either --out-dir or --uproject-dir is required"))?;

        let include_private = command_config.get_one::<bool>("include_private")?.unwrap_or(false);

        runs.push(GenerateRunConfig {
            project_path,
            wasm_file,
            js_file,
            lang,
            namespace,
            module_name,
            module_prefix,
            build_options,
            dotnet_version,
            out_dir,
            include_private,
        });
    }

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