Play with db constraints

bookshop/db/data/sap.capire.bookshop-Authors.csv

@@ -1,5 +1,5 @@
-ID;name;dateOfBirth;placeOfBirth;dateOfDeath;placeOfDeath
-101;Emily Brontë;1818-07-30;Thornton, Yorkshire;1848-12-19;Haworth, Yorkshire
-107;Charlotte Brontë;1818-04-21;Thornton, Yorkshire;1855-03-31;Haworth, Yorkshire
-150;Edgar Allen Poe;1809-01-19;Boston, Massachusetts;1849-10-07;Baltimore, Maryland
-170;Richard Carpenter;1929-08-14;King’s Lynn, Norfolk;2012-02-26;Hertfordshire, England
+ID;name
+101;Emily Brontë
+107;Charlotte Brontë
+150;Edgar Allen Poe
+170;Richard Carpenter

bookshop/db/data/sap.capire.bookshop-Books.csv

@@ -1,6 +1,6 @@
-ID;title;descr;author_ID;stock;price;currency_code;genre_ID
-201;Wuthering Heights;"Wuthering Heights, Emily Brontë's only novel, was published in 1847 under the pseudonym ""Ellis Bell"". It was written between October 1845 and June 1846. Wuthering Heights and Anne Brontë's Agnes Grey were accepted by publisher Thomas Newby before the success of their sister Charlotte's novel Jane Eyre. After Emily's death, Charlotte edited the manuscript of Wuthering Heights and arranged for the edited version to be published as a posthumous second edition in 1850.";101;12;11.11;GBP;11
-207;Jane Eyre;"Jane Eyre /ɛər/ (originally published as Jane Eyre: An Autobiography) is a novel by English writer Charlotte Brontë, published under the pen name ""Currer Bell"", on 16 October 1847, by Smith, Elder & Co. of London. The first American edition was published the following year by Harper & Brothers of New York. Primarily a bildungsroman, Jane Eyre follows the experiences of its eponymous heroine, including her growth to adulthood and her love for Mr. Rochester, the brooding master of Thornfield Hall. The novel revolutionised prose fiction in that the focus on Jane's moral and spiritual development is told through an intimate, first-person narrative, where actions and events are coloured by a psychological intensity. The book contains elements of social criticism, with a strong sense of Christian morality at its core and is considered by many to be ahead of its time because of Jane's individualistic character and how the novel approaches the topics of class, sexuality, religion and feminism.";107;11;12.34;GBP;11
-251;The Raven;"""The Raven"" is a narrative poem by American writer Edgar Allan Poe. First published in January 1845, the poem is often noted for its musicality, stylized language, and supernatural atmosphere. It tells of a talking raven's mysterious visit to a distraught lover, tracing the man's slow fall into madness. The lover, often identified as being a student, is lamenting the loss of his love, Lenore. Sitting on a bust of Pallas, the raven seems to further distress the protagonist with its constant repetition of the word ""Nevermore"". The poem makes use of folk, mythological, religious, and classical references.";150;333;13.13;USD;16
-252;Eleonora;"""Eleonora"" is a short story by Edgar Allan Poe, first published in 1842 in Philadelphia in the literary annual The Gift. It is often regarded as somewhat autobiographical and has a relatively ""happy"" ending.";150;555;14;USD;16
-271;Catweazle;Catweazle is a British fantasy television series, starring Geoffrey Bayldon in the title role, and created by Richard Carpenter for London Weekend Television. The first series, produced and directed by Quentin Lawrence, was screened in the UK on ITV in 1970. The second series, directed by David Reid and David Lane, was shown in 1971. Each series had thirteen episodes, most but not all written by Carpenter, who also published two books based on the scripts.;170;22;15;EUR;13
+ID;title;author_ID;genre_ID
+201;Wuthering Heights;101;11
+207;Jane Eyre;107;11
+251;The Raven;150;16
+252;Eleonora;150;16
+271;Catweazle;170;13

bookshop/db/data/sap.capire.bookshop-Books_texts.csv

@@ -1,5 +1,5 @@
-ID;locale;title;descr
-201;de;Sturmhöhe;Sturmhöhe (Originaltitel: Wuthering Heights) ist der einzige Roman der englischen Schriftstellerin Emily Brontë (1818–1848). Der 1847 unter dem Pseudonym Ellis Bell veröffentlichte Roman wurde vom viktorianischen Publikum weitgehend abgelehnt, heute gilt er als ein Klassiker der britischen Romanliteratur des 19. Jahrhunderts.
-201;fr;Les Hauts de Hurlevent;Les Hauts de Hurlevent (titre original : Wuthering Heights), parfois orthographié Les Hauts de Hurle-Vent, est l'unique roman d'Emily Brontë, publié pour la première fois en 1847 sous le pseudonyme d’Ellis Bell. Loin d'être un récit moralisateur, Emily Brontë achève néanmoins le roman dans une atmosphère sereine, suggérant le triomphe de la paix et du Bien sur la vengeance et le Mal.
-207;de;Jane Eyre;Jane Eyre. Eine Autobiographie (Originaltitel: Jane Eyre. An Autobiography), erstmals erschienen im Jahr 1847 unter dem Pseudonym Currer Bell, ist der erste veröffentlichte Roman der britischen Autorin Charlotte Brontë und ein Klassiker der viktorianischen Romanliteratur des 19. Jahrhunderts. Der Roman erzählt in Form einer Ich-Erzählung die Lebensgeschichte von Jane Eyre (ausgesprochen /ˌdʒeɪn ˈɛə/), die nach einer schweren Kindheit eine Stelle als Gouvernante annimmt und sich in ihren Arbeitgeber verliebt, jedoch immer wieder um ihre Freiheit und Selbstbestimmung kämpfen muss. Als klein, dünn, blass, stets schlicht dunkel gekleidet und mit strengem Mittelscheitel beschrieben, gilt die Heldin des Romans Jane Eyre nicht zuletzt aufgrund der Kino- und Fernsehversionen der melodramatischen Romanvorlage als die bekannteste englische Gouvernante der Literaturgeschichte
-252;de;Eleonora;“Eleonora” ist eine Erzählung von Edgar Allan Poe. Sie wurde 1841 erstveröffentlicht. In ihr geht es um das Paradox der Treue in der Treulosigkeit.
+ID;locale;title
+201;de;Sturmhöhe
+201;fr;Les Hauts de Hurlevent
+207;de;Jane Eyre
+252;de;Eleonora

bookshop/db/data/sap.capire.bookshop-Genres.csv

@@ -14,3 +14,8 @@ ID;parent_ID;name
 22;21;Autobiography
 23;20;Essay
 24;20;Speech
+30;;Others
+31;30;Other-A
+32;30;Other-A
+33;30;Other-A
+34;30;Other-A

bookshop/db/schema.cds

@@ -1,29 +1,19 @@
 using { Currency, managed, sap } from '@sap/cds/common';
 namespace sap.capire.bookshop;
 
-entity Books : managed {
+entity Books {
   key ID : Integer;
   title  : localized String(111);
-  descr  : localized String(1111);
   author : Association to Authors;
   genre  : Association to Genres;
-  stock  : Integer;
-  price  : Decimal;
-  currency : Currency;
-  image : LargeBinary @Core.MediaType : 'image/png';
 }
 
-entity Authors : managed {
+entity Authors {
   key ID : Integer;
   name   : String(111);
-  dateOfBirth  : Date;
-  dateOfDeath  : Date;
-  placeOfBirth : String;
-  placeOfDeath : String;
   books  : Association to many Books on books.author = $self;
 }
 
-/** Hierarchically organized Code List for Genres */
 entity Genres : sap.common.CodeList {
   key ID   : Integer;
   parent   : Association to Genres;

bookshop/index.cds

@@ -1,4 +1,3 @@
 namespace sap.capire.bookshop; //> important for reflection
 using from './db/schema';
-using from './srv/cat-service';
 using from './srv/admin-service';

bookshop/index.js

@@ -1 +0,0 @@
-exports.CatalogService = require('./srv/cat-service')

bookshop/package.json

@@ -3,20 +3,42 @@
   "version": "1.0.0",
   "description": "A simple self-contained bookshop service.",
   "dependencies": {
-    "@capire/common": "*",
     "@sap/cds": "^5.0.4",
     "express": "^4.17.1",
-    "passport": "0.4.1"
+    "passport": "0.4.1",
+    "@sap/hana-client": "^2.7.21"
   },
   "scripts": {
-    "genres": "cds serve test/genres.cds",
-    "start": "cds run",
     "watch": "cds watch"
   },
   "cds": {
     "requires": {
       "db": {
-        "kind": "sql"
+        "kind": "sql",
+        "xxx-model": "*",
+        "xxx-credentials": {
+            "database": "localSqlite.db"
+        }
+      },
+      "[production]": {
+          "db": {
+              "kind": "hana",
+              "model": [
+                  "db",
+                  "srv"
+              ]
+          }
+      }
+    },
+    "features": {
+      "assert_integrity": false
+    },
+    "hana": {
+        "deploy-format": "hdbtable"
+    },
+    "cdsc": {
+      "beta": {
+        "foreignKeyConstraints": true
       }
     }
   }

bookshop/readme.md

@@ -1,31 +1,126 @@
-# Bookshop Getting Started Sample
+# Foreign key constraints on DB
 
-This stand-alone sample introduces the essential tasks in the development of CAP-based services as also covered in the [Getting Started guide in capire](https://cap.cloud.sap/docs/get-started/in-a-nutshell).
+As model we use a simplified version of the bookshop scenario, we work with nodejs runtime.
 
-## Hypothetical Use Cases
 
-1. Build a service that allows to browse _Books_ and _Authors_.
-2. Books have assigned _Genres_, which are organized hierarchically.
-3. All users may browse books without login.
-4. All entries are maintained by Administrators.
-5. End users may order books (the actual order mgmt being out of scope).
+## Preparation
 
-## Running the Sample
-
-```sh
-npm run watch
+As we want to see the effects of the database constaints, we first need to switch off the integrity checks done by the node runtime. In the `package.json`:
+```json
+"cds": {
+  ...,
+  "features": {
+    "assert_integrity": false
+  }
+}
 ```
 
-## Content & Best Practices
+Then switch on constraint generation. In the `package.json`:
+```json
+"cds": {
+  ...,
+  "cdsc": {
+    "beta": {
+      "foreignKeyConstraints": true
+    }
+  }
+}
+```
 
-| Links to capire                                                                                           | Sample files / folders               |
-| --------------------------------------------------------------------------------------------------------- | ------------------------------------ |
-| [Project Setup & Layouts](https://cap.cloud.sap/docs/get-started/projects#sharing-and-reusing-content)    | [`./`](./)                           |
-| [Domain Modeling with CDS](https://cap.cloud.sap/docs/guides/domain-models)                               | [`./db/schema.cds`](./db/schema.cds) |
-| [Defining Services](https://cap.cloud.sap/docs/guides/services#defining-services)                         | [`./srv/*.cds`](./srv)               |
-| [Single-purposed Services](https://cap.cloud.sap/docs/guides/services#single-purposed-services)           | [`./srv/*.cds`](./srv)               |
-| [Providing & Consuming Providers](https://cap.cloud.sap/docs/guides/providing-services)                   | http://localhost:4004                |
-| [Using Databases](https://cap.cloud.sap/docs/guides/databases)                                            | [`./db/data/*.csv`](./db/data)       |
-| [Adding Custom Logic](https://cap.cloud.sap/docs/guides/service-impl)                                     | [`./srv/*.js`](./srv)                |
-| Adding Tests                                                                                              | [`./test`](./test)                   |
-| [Sharing for Reuse](https://cap.cloud.sap/docs/guides/reuse-and-compose)                                  | [`./index.cds`](./index.cds)         |
+## SQLite
+
+In SQLite, FK constraints can only be specified during the creation of a table. They cannot be altered for an existing table. So here we at least don't have issues with existing data.
+
+For SQLite, constraint checks need to be enabled by application at runtime for each db connection with the command
+```sql
+PRAGMA foreign_keys = ON;
+```
+We do this via a custom handler in `admin-service.js`.
+
+Now run the requests in `requests.http` (use `http://localhost:4004` as server URL). They behave as expected.
+
+But the error messages are not providing any details. They say "constraint violation", but they don't say which table/constraint is violated:
+```
+HTTP/1.1 500 Internal Server Error
+...
+{
+  "error": {
+    "code": "SQLITE_CONSTRAINT",
+    "message": "SQLITE_CONSTRAINT: FOREIGN KEY constraint failed in: \nCOMMIT"
+  }
+}
+```
+
+The runtime constraint checks do provide the name of the restricting association (but not the name of the entity where the association lives).
+
+## HANA
+
+Preparation:
+* logon to cf account (e.g. trial)
+* create HANA service instance: `cf create-service hanatrial hdi-shared bookshop-db`
+
+First make the deplyoment without constraints (switch off constraint generation in `package.json`).
+
+* Run `cds build --production`. No constraints are generated.
+* Deploy db model: `cf push -f gen/db`
+* Deploy nodejs app: `cf push -f gen/srv --random-route`. Take note of the app URL.
+
+Run the requests in `request.http` (use the URL from the previous step as server URL, prepend with `https://`).
+Make sure to introduce some data that violates the constraints. No errors are reported - as expected.
+
+Now switch on constraint generation in `package.json`. 
+
+* Run `cds build --production`. The constraints are placed in separate `hdbconstraint` files in `gen\db\src\gen`. They are generated with `VALIDATED ON`.
+* Re-deploy db model: `cf push -f gen/db`. It fails, as the existing data violates the constraints.
+* Check logs: `cf logs bookshop-db-deployer --recent`.
+
+```
+Error: com.sap.hana.di.constraint: Could not create the database object [8250005]
+  at "src/gen/sap.capire.bookshop.Books_author.hdbconstraint" (1:1)
+ Error: com.sap.hana.di.constraint: Database error 7: : feature not supported: referential constraint violated by existing value [8201003]
+   at "src/gen/sap.capire.bookshop.Books_author.hdbconstraint" (1:1)
+```
+You can see which constraint is violated, but there is no info about the offensive entries.
+
+Now use the requests from `request.http` to fix the entries that have been broken above.
+
+* Re-deploy db model: `cf push -f gen/db`. It should succeed.
+
+Again run the requests from `request.http`. This time all changes that would lead to a
+constraint violation fail.
+
+Inserting a book with non-existing author ID or changing a book's author ID to an invalid value yields
+the message
+```
+HTTP/1.1 500 Internal Server Error
+...
+{
+  "error": {
+    "code": "500",
+    "message": "Internal Server Error"
+  }
+}
+```
+When trying to delete a genre that is still referenced in a book we get
+```
+HTTP/1.1 462 status code 462
+...
+{
+  "error": {
+    "code": "462",
+    "message": "failed on update or delete by foreign key constraint violation: TrexColumnUpdate failed on table '21F87859727E470E94917B690908A09D:SAP_CAPIRE_BOOKSHOP_GENRES' with error: DELETE on 21F87859727E470E94917B690908A09D:SAP_CAPIRE_BOOKSHOP_GENRES(ID) failed, because 1 rows with corresponding foreign keys still exist in 21F87859727E470E94917B690908A09D:SAP_CAPIRE_BOOKSHOP_BOOKS(GENRE_ID), rc=1536"
+  }
+}
+```
+
+Note: when using `cdsc` to generate the constraints
+```
+cdsc Q --beta foreignKeyConstraints -d hana -s hdi -o dbstuff db\schema.cds srv\admin-service.cds
+```
+there will be constraints for e.g. `sap_common_Currencies_texts`. This cannot be deplyoed, as the corresponding table is removed from `cds` via the tree-shaking mechanism. These constraints need to be removed manually before deployment.
+
+## Todo
+
+* Provide a way to control parameters `VALIDATED` and `ENFORCED` of the constraints (only interesting for HANA, as in SQLite changing constraints after table generation is not possible).
+* Provide some tool to identify existing entries that violate constraints. We can generate a list of `SELECT` statements that find these entries, but how do we run it and show the results to the user?
+* Can runtimes improve the error messages?

bookshop/srv/admin-service.cds

@@ -1,5 +1,6 @@
 using { sap.capire.bookshop as my } from '../db/schema';
-service AdminService @(requires:'admin') {
+service AdminService {
   entity Books as projection on my.Books;
   entity Authors as projection on my.Authors;
+  entity Genres as projection on my.Genres;
 }

bookshop/srv/admin-service.js

@@ -1,12 +1,15 @@
+// sqlite: FK constraint checks need to be enabled by application at runtime
+// for each db connection
 const cds = require('@sap/cds')
+module.exports = cds.service.impl (async function(){ 
 
-module.exports = cds.service.impl (function(){
-  this.before ('NEW','Authors', genid)
-  this.before ('NEW','Books', genid)
+  const db = await cds.connect.to('db')
+
+  if (db.kind === 'sqlite')
+  {
+    db.before('BEGIN', function (req) { 
+      //console.log('--- PRAGMA foreign_keys = ON ---')
+      return this.dbc.run('PRAGMA foreign_keys = ON;')
+    })
+  }
 })
-
-/** Generate primary keys for target entity in request */
-async function genid (req) {
-  const {ID} = await cds.tx(req).run (SELECT.one.from(req.target).columns('max(ID) as ID'))
-  req.data.ID = ID - ID % 100 + 100 + 1
-}

bookshop/srv/cat-service.cds

@@ -1,16 +0,0 @@
-using { sap.capire.bookshop as my } from '../db/schema';
-service CatalogService @(path:'/browse') {
-
-  /** For displaying lists of Books */
-  @readonly entity ListOfBooks as projection on Books
-  excluding { descr };
-
-  /** For display in details pages */
-  @readonly entity Books as projection on my.Books { *,
-    author.name as author
-  } excluding { createdBy, modifiedBy };
-
-  @requires: 'authenticated-user'
-  action submitOrder ( book: Books:ID, amount: Integer ) returns { stock: Integer };
-  event OrderedBook : { book: Books:ID; amount: Integer; buyer: String };
-}

bookshop/srv/cat-service.js

@@ -1,26 +0,0 @@
-const cds = require('@sap/cds')
-const { Books } = cds.entities ('sap.capire.bookshop')
-
-class CatalogService extends cds.ApplicationService { init(){
-
-  // Reduce stock of ordered books if available stock suffices
-  this.on ('submitOrder', async req => {
-    const {book,amount} = req.data
-    let {stock} = await SELECT `stock` .from (Books,book)
-    if (stock >= amount) {
-      await UPDATE (Books,book) .with (`stock -=`, amount)
-      await this.emit ('OrderedBook', { book, amount, buyer:req.user.id })
-      return { stock }
-    }
-    else return req.error (409,`${amount} exceeds stock for book #${book}`)
-  })
-
-  // Add some discount for overstocked books
-  this.after ('READ','ListOfBooks', each => {
-    if (each.stock > 111) each.title += ` -- 11% discount!`
-  })
-
-  return super.init()
-}}
-
-module.exports = { CatalogService }

bookshop/test/genres.cds

@@ -1,4 +0,0 @@
-using { sap.capire.bookshop as my } from '../db/schema';
-service TestService {
-  entity Genres as projection on my.Genres;
-}

bookshop/test/genres.http

@@ -1,38 +0,0 @@
-#################################################
-#
-#   Genres
-#
-
-GET http://localhost:4004/test/Genres?
-###
-
-GET http://localhost:4004/test/Genres?
-&$filter=parent_ID eq null&$select=name
-&$expand=children($select=name)
-###
-
-POST http://localhost:4004/test/Genres?
-Content-Type: application/json
-
-{ "ID":100, "name":"Some Sample Genres...", "children":[
-    { "ID":101, "name":"Cat", "children":[
-        { "ID":102, "name":"Kitty", "children":[
-            { "ID":103, "name":"Kitty Cat", "children":[
-                { "ID":104, "name":"Aristocat" } ]},
-            { "ID":105, "name":"Kitty Bat" } ]},
-        { "ID":106, "name":"Catwoman", "children":[
-            { "ID":107, "name":"Catalina" } ]} ]},
-    { "ID":108, "name":"Catweazle" }
-]}
-###
-
-GET http://localhost:4004/test/Genres(100)?
-# &$expand=children
-# &$expand=children($expand=children($expand=children($expand=children)))
-###
-
-DELETE http://localhost:4004/test/Genres(103)
-###
-
-DELETE http://localhost:4004/test/Genres(100)
-###

bookshop/test/requests.http

@@ -1,82 +1,68 @@
+# running locally
 @server = http://localhost:4004
-@me = Authorization: Basic {{$processEnv USER}}:
+
+# running on cf
+#@server = https://bookshop-srv-....hana.ondemand.com
+
+### get all books
+GET {{server}}/admin/Books
+
+### get all authors
+GET {{server}}/admin/Authors
+
+### get all genres
+GET {{server}}/admin/Genres
 
 
-### ------------------------------------------------------------------------
-# Get service info
-GET {{server}}/browse
-{{me}}
-
-
-### ------------------------------------------------------------------------
-# Get $metadata document
-GET {{server}}/browse/$metadata
-{{me}}
-
-
-### ------------------------------------------------------------------------
-# Browse Books as any user
-GET {{server}}/browse/Books?
-  # &$select=title,stock
-  # &$expand=currency
-  # &sap-language=de
-{{me}}
-
-
-### ------------------------------------------------------------------------
-# Fetch Authors as admin
-GET {{server}}/admin/Authors?
-  # &$select=name,dateOfBirth,placeOfBirth
-  # &$expand=books($select=title;$expand=currency)
-  # &$filter=ID eq 101
-  # &sap-language=de
-Authorization: Basic alice:
-
-### ------------------------------------------------------------------------
-# Create book
+### create book with wrong author ID -> should fail
 POST {{server}}/admin/Books
-Content-Type: application/json;IEEE754Compatible=true
-Authorization: Basic alice:
+Content-Type: application/json
 
 {
-  "ID": 2,
-  "title": "Poems : Pocket Poets",
-  "descr": "The Everyman's Library Pocket Poets hardcover series is popular for its compact size and reasonable price which does not compromise content. Poems: Bronte contains poems that demonstrate a sensibility elemental in its force with an imaginative discipline and flexibility of the highest order. Also included are an Editor's Note and an index of first lines.",
-  "author": { "ID": 101 },
-  "genre": { "ID": 12 },
-  "stock": 5,
-  "price": "12.05",
-  "currency": { "code": "USD" }
+  "ID": 701,
+  "title": "XXX",
+  "author": { "ID": 9999 }
 }
 
+### create book with correct author ID -> should work
+POST {{server}}/admin/Books
+Content-Type: application/json;IEEE754Compatible=true
 
-### ------------------------------------------------------------------------
-# Put image to books
-PUT {{server}}/admin/Books(2)/image
-Content-Type: image/png
-Authorization: Basic alice:
+{
+  "ID": 702,
+  "title": "Poems : Pocket Poets",
+  "author": { "ID": 101 }
+}
 
-data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAANwAAADcCAYAAAAbWs+BAAAGwElEQVR4Ae3cwZFbNxBFUY5rkrDTmKAUk5QT03Aa44U22KC7NHptw+DRikVAXf8fzC3u8Hj4R4AAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAgZzAW26USQT+e4HPx+Mz+RRvj0e0kT+SD2cWAQK1gOBqH6sEogKCi3IaRqAWEFztY5VAVEBwUU7DCNQCgqt9rBKICgguymkYgVpAcLWPVQJRAcFFOQ0jUAsIrvaxSiAqILgop2EEagHB1T5WCUQFBBflNIxALSC42scqgaiA4KKchhGoBQRX+1glEBUQXJTTMAK1gOBqH6sEogKCi3IaRqAWeK+Xb1z9iN558fHxcSPS9p2ezx/ROz4e4TtIHt+3j/61hW9f+2+7/+UXbifjewIDAoIbQDWSwE5AcDsZ3xMYEBDcAKqRBHYCgtvJ+J7AgIDgBlCNJLATENxOxvcEBgQEN4BqJIGdgOB2Mr4nMCAguAFUIwnsBAS3k/E9gQEBwQ2gGklgJyC4nYzvCQwICG4A1UgCOwHB7WR8T2BAQHADqEYS2AkIbifjewIDAoIbQDWSwE5AcDsZ3xMYEEjfTzHwiK91B8npd6Q8n8/oGQ/ckRJ9vvQwv3BpUfMIFAKCK3AsEUgLCC4tah6BQkBwBY4lAmkBwaVFzSNQCAiuwLFEIC0guLSoeQQKAcEVOJYIpAUElxY1j0AhILgCxxKBtIDg0qLmESgEBFfgWCKQFhBcWtQ8AoWA4AocSwTSAoJLi5pHoBAQXIFjiUBaQHBpUfMIFAKCK3AsEUgLCC4tah6BQmDgTpPsHSTFs39p6fQ7Q770UsV/Ov19X+2OFL9wxR+rJQJpAcGlRc0jUAgIrsCxRCAtILi0qHkECgHBFTiWCKQFBJcWNY9AISC4AscSgbSA4NKi5hEoBARX4FgikBYQXFrUPAKFgOAKHEsE0gKCS4uaR6AQEFyBY4lAWkBwaVHzCBQCgitwLBFICwguLWoegUJAcAWOJQJpAcGlRc0jUAgIrsCxRCAt8J4eePq89B0ar3ZnyOnve/rfn1+400/I810lILirjtPLnC4guNNPyPNdJSC4q47Ty5wuILjTT8jzXSUguKuO08ucLiC400/I810lILirjtPLnC4guNNPyPNdJSC4q47Ty5wuILjTT8jzXSUguKuO08ucLiC400/I810lILirjtPLnC4guNNPyPNdJSC4q47Ty5wuILjTT8jzXSUguKuO08ucLiC400/I810l8JZ/m78+szP/zI47fJo7Q37vgJ7PHwN/07/3TOv/9gu3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhAcMPAxhNYBQS3avhMYFhg4P6H9J0maYHXuiMlrXf+vOfA33Turf3C5SxNItAKCK4lsoFATkBwOUuTCLQCgmuJbCCQExBcztIkAq2A4FoiGwjkBASXszSJQCsguJbIBgI5AcHlLE0i0AoIriWygUBOQHA5S5MItAKCa4lsIJATEFzO0iQCrYDgWiIbCOQEBJezNIlAKyC4lsgGAjkBweUsTSLQCgiuJbKBQE5AcDlLkwi0Akff//Dz6U+/I6U1/sUNr3bnytl3kPzi4bXb/cK1RDYQyAkILmdpEoFWQHAtkQ0EcgKCy1maRKAVEFxLZAOBnIDgcpYmEWgFBNcS2UAgJyC4nKVJBFoBwbVENhDICQguZ2kSgVZAcC2RDQRyAoLLWZpEoBUQXEtkA4GcgOByliYRaAUE1xLZQCAnILicpUkEWgHBtUQ2EMgJCC5naRKBVkBwLZENBHIC/4M7TXIv+3PS22d24qvdQfL3C/7N5P5i/MLlLE0i0AoIriWygUBOQHA5S5MItAKCa4lsIJATEFzO0iQCrYDgWiIbCOQEBJezNIlAKyC4lsgGAjkBweUsTSLQCgiuJbKBQE5AcDlLkwi0AoJriWwgkBMQXM7SJAKtgOBaIhsI5AQEl7M0iUArILiWyAYCOQHB5SxNItAKCK4lsoFATkBwOUuTCBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIAAAQIECBAgQIDAvyrwDySEJ2VQgUSoAAAAAElFTkSuQmCC
+### delete book
+DELETE {{server}}/admin/Books(ID=701)
+
+### change book to wrong author ID -> should fail
+
+PATCH {{server}}/admin/Books(ID=207)
+Content-Type:application/json
+
+{"author_ID": 9999}
+
+### change book to correct author ID -> should work
+
+PATCH {{server}}/admin/Books(ID=207)
+Content-Type:application/json
+
+{"author_ID": 170}
 
 
-### ------------------------------------------------------------------------
-# Reading image from from the server directly
-GET {{server}}/browse/Books(2)/image
+
+### delete "leaf" genre that is used in a book -> should not work
+DELETE {{server}}/admin/Genres(ID=13)
+
+### delete "leaf" genre that is not used in a book -> should work
+DELETE {{server}}/admin/Genres(ID=14)
 
 
-### ------------------------------------------------------------------------
-# Submit Order as authenticated user
-# (send that three times to get out-of-stock message)
-POST {{server}}/browse/submitOrder
-Content-Type: application/json
-{{me}}
-
-{ "book":201, "amount":5 }
+### delete "header" genre where leaves are used in a book -> should not work
+DELETE {{server}}/admin/Genres(ID=10)
 
 
-### ------------------------------------------------------------------------
-# Browse Genres
-GET {{server}}/browse/Genres?
-# &$filter=parent_ID eq null&$select=name
-# &$expand=children($select=name)
-{{me}}
+### delete "header" genre where leaves are not used in a book -> should work and delete all leaves
+DELETE {{server}}/admin/Genres(ID=30)