gastownhall/beads · error

template execution error: %w

Error message

template execution error: %w

What it means

During `bd list --format` rendering, executing the parsed template against each issue's data map failed. Unlike parse errors, this happens per-record at render time — e.g. calling a function with wrong argument types or on a nil field. Output is buffered per issue, so a failure aborts before writing partial rows.

Source

Thrown at cmd/bd/list_output.go:144

	}

	// For each issue, output its dependencies using the template
	for _, issue := range issues {
		for _, dep := range depsByIssueID[issue.ID] {
			// Only output edges where both nodes are in the filtered list
			if issueMap[dep.DependsOnID] {
				// Template data includes both issue and dependency info
				data := map[string]interface{}{
					"IssueID":     issue.ID,
					"DependsOnID": dep.DependsOnID,
					"Type":        dep.Type,
					"Issue":       issue,
					"Dependency":  dep,
				}

				var buf bytes.Buffer
				if err := tmpl.Execute(&buf, data); err != nil {
					return fmt.Errorf("template execution error: %w", err)
				}
				w.println(buf.String())
				if err := w.wrapError("formatted list"); err != nil {
					return err
				}
			}
		}
	}

	return w.wrapError("formatted list")
}

View on GitHub (pinned to 71377f2769)

Solutions

1. Read the wrapped template error for the failing field/operation
2. Cast or format correctly: {{printf "%s" .Title}} not {{printf "%d" .Title}}
3. Reference available map keys only: .Issue and .Dependency
4. Simplify to plain field access ({{.ID}} {{.Status}}) and add functions back incrementally

Example fix

// before
--format '{{printf "%d" .ID}}'
// after
--format '{{printf "%s" .ID}}'

// Validate field types before formatting: .ID is a string
// Bad:  --format '{{printf "%d" .ID}}'
// Good: --format '{{printf "%s" .ID}}'
bd list --format '{{printf "%s" .ID}}' --limit 1 >/dev/null || echo "template fails at execution"

// Test the template on one record before a full run
if ! bd list --format "$tpl" --limit 1 >/dev/null 2>&1; then
  bd list --format "$tpl" --limit 1 # show the template execution error
fi

When it happens

Trigger: A --format template that parses but fails at Execute — e.g. {{.Title | printf "%d"}} (type mismatch), calling an undefined method on Issue, or nil dereference on missing fields.

Common situations: Format strings using wrong field types (formatting a string as int), templates assuming fields exist on every issue, or copy-pasted templates referencing unavailable data keys (Issue/Dependency map keys).

Related errors

• invalid format template: %w
• template %s not found
• no proto found matching %q (by ID or title)
• ambiguous: %q matches %d protos: %s Use the ID or a more s
• ErrAmbiguousID

AI-assisted analysis of gastownhall/beads@71377f2769 (2026-08-30). Data as JSON: /api/errors/00442594d88aa6b1. Report an issue: GitHub.