constraints on service level

bookshop/server.js

@@ -1,19 +1,31 @@
 //
 //  Quick and dirty implementation for cds.validate() using db-level constraints
 //  Test in cds.repl like that:
+//  {Books} = AdminService.entities
 //  await cds.run (()=> INSERT.into (Books, { title:'   ', author_ID:150 }) .then (cds.validate(Books)))
+//  await AdminService.create ('Books', { title:'   ', author_ID:150 })
 //
 
 const cds = require('@sap/cds')
 cds.on('served', ()=> {
 
-  const $ = cds.validate; cds.validate = function (entity, key, ...columns) {
+  const $ = cds.validate
+  cds.validate = function (entity, key, ...columns) {
 
-    if (!entity.is_entity) return $(...arguments)
-    if (!key) return key => cds.validate(entity,key)
+    if (entity?.ref) entity = { // quick and dirty
+      name: entity.ref[0],
+      constraints: { // even quicker and dirtier
+        name: entity.ref[0] +'.constraints',
+        keys: {ID:1}
+      }
+    }
+    else if (!entity.is_entity) return // we skip all standard validations for the experiments
+    else if (!entity.is_entity) return $(...arguments) // eslint-disable-line no-dupe-else-if
 
     if (entity.constraints) entity = entity.constraints
-    if (key.results) key = key.results[0].lastInsertRowid
+    if (!key) return key => cds.validate(entity,key)
+    if (key.results) key = key.results[0].lastInsertRowid // quick and dirty
+    if (key.ID) key = key.ID // quick and dirty
 
     return SELECT.one.from (entity, key, columns.length && columns) .then (checks => {
       const failed = {}; for (let c in checks) {
@@ -25,6 +37,8 @@ cds.on('served', ()=> {
     })
   }
 
+  const { AdminService } = cds.services
+  AdminService.after (['CREATE','UPDATE'], (result,req) =>  cds.validate (req.subject, result))
 })
 
 Object.defineProperties (cds.entity.prototype, {

bookshop/srv/access-control.cds

@@ -1,2 +1,2 @@
 using { AdminService } from './admin-service';
-annotate AdminService with @requires:'admin';
+annotate AdminService with @requires: false; //'admin';

bookshop/srv/admin-service.cds

@@ -1,6 +1,6 @@
 using { sap.capire.bookshop as my } from '../db/schema';
 service AdminService @(path:'/admin') {
-  entity Authors as projection on my.Authors;
+  entity Authors as projection on my.Authors excluding { books};
   entity Books as projection on my.Books;
   entity Genres as projection on my.Genres;
 }

bookshop/srv/x-validation.cds

@@ -1,61 +1,76 @@
-namespace sap.capire.bookshop;
-using from '../db/schema';
+using { AdminService, sap.capire.bookshop as my } from './admin-service';
+
+extend service AdminService with {
+
+  // entity Books.drafts as projection on AdminService.Books;
+  // @cds.api.ignore view Books.drafts.constraints as select from AdminService.Books.drafts mixin {
+  //   before: Association to my.Books on before.ID = $self.ID;
+  //   base: Association to my.Books on base.ID = $self.ID;
+  // } into { ID, // FIXME: compiler should resolve Books without AdminService prefix
+  //   case
+  //     when title is null  then 'is missing'
+  //     when trim(title)='' then 'must not be empty'
+  //   end as title,
+  //   ...
+  // }
+
+  /**
+   * Validation constraints for Books
+   */
+  @cds.api.ignore view Books.constraints as select from AdminService.Books mixin {
+    base: Association to my.Books on base.ID = $self.ID;
+  } into { ID, // FIXME: compiler should resolve Books without AdminService prefix
+
+    // two-step mandatory check
+    case
+      when title is null  then 'is missing'
+      when trim(title)='' then 'must not be empty'
+    end as title,
+    // the above is equivalent to:
+    // title is null ? 'is missing' : trim(title)='' ? 'must not be empty' :
+
+    // range check
+    stock < 0 ? 'must not be negative' :
+    null as stock,
+
+    // range check
+    price < 0 ? 'must not be negative' :
+    null as price,
+
+    // assert target check
+    genre.ID is not null and not exists genre ? 'does not exist' :
+    null as genre,
+
+    // multiple constraints: mandatory + assert target + special
+    author.ID is null ? 'is missing' : // FIXME: 1) // TODO: 2)
+    not exists author ? 'Author does not exist: ' || author.ID :
+    count(base.author.books.ID) -1 > 1 ? author.name || ' already wrote too many books' : // TODO: 3)
+    null as author,
+
+  } group by ID;
+
+  // 1) FIXME: expected author.ID to refer to foreign key,
+  // apparently that is not the case -> move one line up
+  // and run test to see the erroneous impact.
+
+  // 2) TODO: we should allow to write author is null instead of author.ID is null
+
+  // 3) TODO: we should support count(author.books)
 
 
-/**
- * Validation constraints for Books
- */
-view Books.constraints as select from Books { ID,
+  /**
+   * Validation constraints for Authors
+   */
+  view Authors.constraints as select from AdminService.Authors { ID, // FIXME: compiler should resolve Authors without AdminService prefix
 
-  // two-step mandatory check
-  case
-    when title is null  then 'is missing'
-    when trim(title)='' then 'must not be empty'
-  end as title,
-  // the above is equivalent to:
-  // title is null ? 'is missing' : trim(title)='' ? 'must not be empty' :
+    // two-step mandatory check
+    name = null ? 'is missing' : trim(name)='' ? 'must not be empty' :
+    null as name,
 
-  // range check
-  stock < 0 ? 'must not be negative' :
-  null as stock,
-
-  // range check
-  price < 0 ? 'must not be negative' :
-  null as price,
-
-  // assert target check
-  genre.ID is not null and not exists genre ? 'does not exist' :
-  null as genre,
-
-  // multiple constraints: mandatory + assert target + special
-  author.ID is null ? 'is missing' : // FIXME: 1) // TODO: 2)
-  not exists author ? 'Author does not exist: ' || author.ID :
-  count(author.books.ID) -1 > 1 ? author.name || ' already wrote too many books' : // TODO: 3)
-  null as author,
-
-} group by ID;
-
-// 1) FIXME: expected author.ID to refer to foreign key,
-// apparently that is not the case -> move one line up
-// and run test to see the erroneous impact.
-
-// 2) TODO: we should allow to write author is null instead of author.ID is null
-
-// 3) TODO: we should support count(author.books)
-
-
-/**
- * Validation constraints for Authors
- */
-view Authors.constraints as select from Authors { ID,
-
-  // two-step mandatory check
-  name = null ? 'is missing' : trim(name)='' ? 'must not be empty' :
-  null as name,
-
-  // constraint related to two fields
-  dateOfDeath > dateOfBirth ? 'we must be born before we die' : null as _born_before_death,
-  $self._born_before_death as dateOfBirth,
-  $self._born_before_death as dateOfDeath,
+    // constraint related to two fields
+    dateOfDeath > dateOfBirth ? 'we must be born before we die' : null as _born_before_death,
+    $self._born_before_death as dateOfBirth,
+    $self._born_before_death as dateOfDeath,
 
+  }
 }