1 files changed, 240 insertions, 0 deletions
diff --git a/src/app/db/service/base/helpers.js b/src/app/db/service/base/helpers.js
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+/**
+ * Service construction helpers
+ * @module app/db/service/base/helpers
+ */
+
+import {
+  checkPermission,
+  checkParentPermission,
+} from "app/services/permission/helpers";
+import { sendResponse } from "app/db/service/base/response";
+
+/**
+ * Returns a helper function used by an iterator when creating custom routes.
+ * @param {Service} service   the affected service
+ * @param {Service} methods   the CRUD methods associated with the service
+ * @returns {Function}        the method called on the iterable
+ */
+export function createCustomRoute(service, methods) {
+  const { parent } = service.options;
+  /**
+   * Create a custom route.  If the route contains `/:id`, the record will be fetched before calling the handlers.
+   * @param {string} method      the method name
+   * @param {string} route       the route to mount on
+   * @param {Array}  handlers    a list of middleware
+   * @param {Object} permissions a permissions object
+   */
+  return function addCustomRouteHandler({
+    method,
+    route,
+    handlers,
+    permissions,
+  }) {
+    service.router[(method || "get").toLowerCase()](
+      route,
+      (parent ? [checkParentPermission(parent)] : [])
+        .concat(permissions ? [checkPermission(permissions)] : [])
+        .concat(route.match(/^\/:id/) ? methods.show(service) : [])
+        .concat(handlers)
+        .concat([sendResponse])
+    );
+  };
+}
+
+/**
+ * Returns a helper function used by an iterator when creating CRUD routes.
+ * @param {Service} service   the affected service
+ * @param {Object}  methods   a set of methods to use
+ * @returns {Function}        the method called on the iterable
+ */
+export function createCrudRoute(service, methods) {
+  const { parent, permissions, hooks, logging } = service.options;
+  const loggingHook = logging ? [logging] : [];
+  /**
+   * Create a CRUD route
+   * @param {string} type  the type of route to create
+   */
+  return function addEnabledRoute(type) {
+    const beforeHooks = hooks?.before[type] || [];
+    const afterHooks = hooks?.after[type] || [];
+    let verb, route, handlers;
+    switch (type) {
+      case "index":
+        verb = "get";
+        route = "/";
+        handlers = [
+          checkPermission(permissions, "read"),
+          ...beforeHooks,
+          methods.index(service),
+        ];
+        break;
+      case "show":
+        verb = "get";
+        route = "/:id";
+        handlers = [
+          checkPermission(permissions, "read"),
+          ...beforeHooks,
+          methods.show(service),
+        ];
+        break;
+      case "create":
+        verb = "post";
+        route = "/";
+        handlers = [
+          checkPermission(permissions, "create"),
+          ...beforeHooks,
+          methods.create(service),
+          ...loggingHook,
+        ];
+        break;
+      case "update":
+        verb = "put";
+        route = "/:id";
+        handlers = [
+          checkPermission(permissions, "read"),
+          ...(hooks?.before?.show || []),
+          methods.show(service),
+          ...beforeHooks,
+          checkPermission(permissions, "update"),
+          methods.update(service),
+          ...loggingHook,
+        ];
+        break;
+      case "updateMany":
+        verb = "put";
+        route = "/";
+        handlers = [
+          checkPermission(permissions, "read"),
+          methods.showMany(service),
+          ...beforeHooks,
+          checkPermission(permissions, "update"),
+          methods.updateMany(service),
+          ...loggingHook,
+        ];
+        break;
+      case "sort":
+        verb = "post";
+        route = "/sort";
+        handlers = [
+          checkPermission(permissions, "read"),
+          ...beforeHooks,
+          checkPermission(permissions, "update"),
+          methods.sort(service),
+          // ...loggingHook,
+        ];
+        break;
+      case "destroy":
+        verb = "delete";
+        route = "/:id";
+        handlers = [
+          checkPermission(permissions, "read"),
+          methods.show(service),
+          ...beforeHooks,
+          checkPermission(permissions, "destroy"),
+          methods.destroy(service),
+          ...loggingHook,
+        ];
+        break;
+      case "destroyMany":
+        verb = "delete";
+        route = "/";
+        handlers = [
+          checkPermission(permissions, "read"),
+          ...beforeHooks,
+          // above, i'm using show to see if the records exist before deleting them
+          // but if deleting many, this is probably being done on the pivot table,
+          // and where the check is accomplished implicitly by the destroy middleware.
+          // if delete permission is ALLOW_FOR_OWNER, we still have to make the check.
+          // methods.showMany(service),
+          checkPermission(permissions, "destroy"),
+          methods.destroyMany(service),
+          ...loggingHook,
+        ];
+        break;
+      default:
+        console.error(`Unknown route: ${type}`);
+        return;
+    }
+    let routeHandlers = []
+      .concat(
+        parent
+          ? [formatParentParameters(service), checkParentPermission(parent)]
+          : []
+      )
+      .concat(handlers)
+      .concat(afterHooks)
+      .concat(type === "destroy" ? [onDestroyCleanupResponse] : [])
+      .concat([sendResponse]);
+    service.router[verb](
+      route,
+      routeHandlers.filter((handler) => !!handler)
+    );
+  };
+}
+
+/**
+ * Helper function to convert request.params to integers where appropriate
+ */
+export function formatParentParameters(service) {
+  const parentIdAttributes = service.idAttributes.slice(1);
+  return function formatParentParametersMiddleware(request, response, next) {
+    const hasInvalidParams = parentIdAttributes.some((parentIdAttribute) => {
+      const value = parseInt(request.params[parentIdAttribute]);
+      if (!value) {
+        return true;
+      }
+      request.params[parentIdAttribute] = value;
+      return false;
+    });
+    if (hasInvalidParams) {
+      return next(new Error("malformed parent ID"));
+    }
+    next();
+  };
+}
+
+/**
+ * Helper function to clean up local data.  We make the deleted object available to middleware, but not to the client.
+ * @param  {express.request}  request  the request object
+ * @param  {express.response} response the response object
+ * @param  {function}         next     function to proceed to the next middleware
+ */
+export function onDestroyCleanupResponse(request, response, next) {
+  delete response.locals.data;
+  delete response.locals.child;
+  next();
+}
+
+/**
+ * For each returned object, fetch the count of a particular relation
+ * @param  {string} relation   name of relation
+ * @param  {string} valueName  (optional) name of the value to set on the output object, defaults to `{relation}_count``
+ * @return {Function}          middleware function (`after` hook)
+ */
+export function getRelationCount(relation, as, where) {
+  return async function getRelationCountMiddleware(request, response, next) {
+    if (!response.locals.data) {
+      return next();
+    }
+    const countField = relation + "_count";
+    const items =
+      "length" in response.locals.data
+        ? response.locals.data
+        : [response.locals.data];
+    const getCountPromises = items.map(async (item) => {
+      if (!item || !item.related || countField in item) return;
+      const itemRelation = item.related(relation);
+      if (where) {
+        itemRelation.where(where);
+      }
+      const count = await itemRelation.count();
+      item.set(as || countField, count);
+    });
+    try {
+      await Promise.all(getCountPromises);
+    } catch (error) {
+      console.error(error);
+    }
+    next();
+  };
+}