gointerop

Go Imports

This example shows the supported .gwdk to Go import slice: a page imports a Go package by module path and calls a no-argument build-time function from build {}.

What works today:

• .gwdk page files can declare a top-level aliased import: import interop "github.com/cssbruno/gowdk/examples/go-interop".
• The .gwdk package declaration still matches the sibling Go package: package gointerop.
• build {} can call one no-argument imported Go function: => interop.FeaturedCopyForBuild().
• Build-time Go calls can also use a bare same-package helper when the page directory is a buildable Go package.
• Build helpers can return T or (T, error).
• The returned value must JSON-encode to an object. Scalar fields become string interpolation data for view {}.
• Successful stderr logging from the helper is kept separate from the JSON payload.
• Literal build {} and paths {} records still work in other examples.

What does not work yet:

• Arbitrary Go statements inside build {} are not supported.
• Passing route params into Go build functions is not supported yet.
• Generated per-route param structs and typed load/action result accessors are deferred.

catalog.go is the imported application code. The .gwdk page uses the import as its main data path, with no literal fallback.

go run ./cmd/gowdk build --out /tmp/gowdk-go-interop examples/go-interop/imported-build.page.gwdk
test -f /tmp/gowdk-go-interop/go-imported/index.html

Run the command from the repository root so the required root gowdk.config.go is loaded, or pass an explicit --config <file>.

Real-world slice: validation + structured logging

newsletter.go shows a page delegating serious behavior to standard-library packages instead of inline or generated logic. SubscriberDigestForBuild:

• parses and validates a raw subscriber list with net/mail (mail.ParseAddress), so malformed entries are rejected by a real parser;
• emits log/slog structured build logs to stderr, which GOWDK keeps separate from the JSON build payload; and
• returns a digest (validCount, rejectedCount, sampleDomains) that the page interpolates — including integer fields, which render as strings.

What is real: the net/mail validation, the log/slog logging, and the stderr/JSON separation are genuine.

What is mocked: rawSubscribers is a hardcoded slice standing in for a real data source (a database/sql/pgx query, a CRM export, or a drained queue). Swap it for your data layer and the .gwdk build contract is unchanged.

What is omitted, on purpose: this example uses only the standard library so it adds no production dependency. Demonstrating database/sql, pgx, sqlc, markdown, email-sending, image, or queue packages follows the same import + build {} pattern, but adding those would need a real dependency reviewed under dependency-policy.md. The root module deliberately keeps its direct-dependency surface tiny.

go run ./cmd/gowdk check examples/go-interop/newsletter-digest.page.gwdk
go run ./cmd/gowdk build --out /tmp/gowdk-newsletter examples/go-interop/newsletter-digest.page.gwdk
grep -F 'Valid subscribers: 3' /tmp/gowdk-newsletter/go-newsletter/index.html

gowdk check over examples/go-interop/*.gwdk runs in CI (scripts/check-example-reports.sh), so this page is validated on every build and cannot silently rot.