## Una aplicación con callbacks { #an-app-with-callbacks }

Veamos todo esto con un ejemplo.

Imagina que desarrollas una aplicación que permite crear facturas.

Estas facturas tendrán un `id`, `title` (opcional), `customer` y `total`.

El usuario de tu API (un desarrollador externo) creará una factura en tu API con un request POST.

Luego tu API (imaginemos):

* Enviará la factura a algún cliente del desarrollador externo.

        final CreateForm form = new CreateForm();
        form.doc = new HashMap<>();
        form.doc.put("url", "https://example.com");
        form.doc.put("title", "Test");
        form.doc.put("custom_metadata", "custom value");
        form.doc.put("department", "Engineering");

        final java.lang.reflect.Field currentFormField = AdminSearchlistAction.class.getDeclaredField("currentForm");
        currentFormField.setAccessible(true);

        if (lookup == null) {
            return customLifecycles != null ? customLifecycles : new HashMap<>();
        }

        // Lifecycles cannot be cached as extensions might add custom lifecycles later in the execution.
        try {
            return registry != null
                    ? registry.stream().collect(Collectors.toMap(lf -> lf.id(), lf -> new Lifecycle(registry, lf)))

/**
 * Copies the Rest YAML test to the current projects test resources output directory.
 * This is intended to be be used from {@link RestResourcesPlugin} since the plugin wires up the needed
 * configurations and custom extensions.
 *
 * @see RestResourcesPlugin
 */
public class CopyRestTestsTask extends DefaultTask {
    private static final String REST_TEST_PREFIX = "rest-api-spec/test";

// functions are defined in this package for scanning a file into
// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
// client may instead provide a custom split function.
//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the [Scanner.Buffer]. When a scan stops, the reader may have

These functions are there (instead of just using the classes directly) so that your editor doesn't mark errors about their types.

That way you can use your normal editor and coding tools without having to add custom configurations to disregard those errors.

It used custom types in its declarations instead of standard Python types, but it was still a huge step forward.

It also was one of the first frameworks to generate a custom schema declaring the whole API in JSON.

nindent 10 }} {{- end }} resources: {{ toYaml .Values.makeUserJob.resources | indent 10 }} {{- end }} minio/templates/post-install-custom-command.yaml {{- if .Values.customCommands }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-custom-command-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-custom-command-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook":...

.Values.configPathmc }}certs {{ end }} resources: {{ toYaml .Values.makeUserJob.resources | indent 10 }} {{- end }} minio/templates/post-install-custom-command.yaml {{- if .Values.customCommands }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-custom-command-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-custom-command-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook":...

        return ComponentUtil.getSearchEngineClient().update(ComponentUtil.getFessConfig().getIndexDocumentUpdateIndex(), id, field, value);
    }

    /**
     * Updates a document using a custom update request builder.
     *
     * @param id The document ID to update
     * @param builderLambda Consumer function to configure the update request builder
     * @return true if the update was successful, false otherwise