30分鐘用Restful ABAP Programming模型開發一個支援增刪改查的Fiori應用

這個系列的部落格集可以在Jerry這篇公眾號文章裡獲得：Jerry的通過CDS view + Smart Template 開發Fiori應用的blog合集。

三年的時間過去了，ABAP在不斷向前進化，如今我們有了新的程式設計模型：Restful ABAP Programming模型，簡稱為RAP模型。該模型定義了一套架構體系，應用開發人員能夠憑藉其來高效地進行應用的端到端開發，這種應用具有與生俱來的Restful特質，能充分利用HANA平臺的強大計算能力，支援雲環境和Fiori UX。

RAP模型的三大支柱：

Business Service
Core Data Service
Behavior Definition

下面請跟著Jerry一起，通過一個實際的例子，瞭解一下這種全新的通過Restful ABAP Programming模型進行Fiori應用開發的步驟吧。

Jerry還是沿用傳統ABAP On-Premises程式設計培訓教材裡使用過的經典的SFLIGHT模型來作為底層資料庫儲存。

(1）首先建立一個數據庫表ZTRAVEL_JERRY：(如果想複製這段原始碼，請點選文末的“閱讀原文”獲得)

@EndUserText.label : 'Database table for travel data XXX'
@AbapCatalog.enhancementCategory : #NOT_EXTENSIBLE
@AbapCatalog.tableCategory : #TRANSPARENT
@AbapCatalog.deliveryClass : #A
@AbapCatalog.dataMaintenance : #LIMITED
define table ztravel_jerry {
  key client      : abap.clnt not null;
  key travel_id   : /dmo/travel_id not null;
  agency_id       : /dmo/agency_id;
  customer_id     : /dmo/customer_id;
  begin_date      : /dmo/begin_date;
  end_date        : /dmo/end_date;
  @Semantics.amount.currencyCode : 'ztravel_jerry.currency_code'
  booking_fee     : /dmo/booking_fee;
  @Semantics.amount.currencyCode : 'ztravel_jerry.currency_code'
  total_price     : /dmo/total_price;
  currency_code   : /dmo/currency_code;
  description     : /dmo/description;
  created_by      : syuname;
  created_at      : timestampl;
  last_changed_by : syuname;
  last_changed_at : timestampl;

}

因為我們在ABAP Development Tools裡無法用事務碼SE16手動往這張表裡插入資料，所以我建立一個ABAP類，用ABAP程式碼往這個表裡插入三條資料。

按F9執行這個ABAP類，然後看到三條資料成功插入了：

(2) 我們最終的目的是建立一個支援對這張表進行增刪改查的Fiori應用，而Restful ABAP Programming模型的三大支柱之一為Core Data Service，因此我們首先得有基於資料庫表ZTRAVEL_JERRY的CDS view.

所以我首先建立一個CDS view：

@AbapCatalog.sqlViewName: 'ZVI_TRAVEL'
@AbapCatalog.compiler.compareFilter: true
@AbapCatalog.preserveKey: true
@AccessControl.authorizationCheck: #CHECK
@EndUserText.label: 'Travel data - XXX'
define root view ZI_TRAVEL_JERRY

 as select from ztravel_jerry as Travel

 /* Associations */
 association [0..1] to /DMO/I_Agency   as _Agency   on $projection.agency_id = _Agency.AgencyID
 association [0..1] to /DMO/I_Customer as _Customer on $projection.customer_id = _Customer.CustomerID
 association [0..1] to I_Currency      as _Currency on $projection.currency_code = _Currency.Currency
 {
  key travel_id,
     agency_id,
     customer_id,
     begin_date,
     end_date,
     @Semantics.amount.currencyCode: 'currency_code'
     booking_fee,
     @Semantics.amount.currencyCode: 'currency_code'
     total_price,
     @Semantics.currencyCode: true
     currency_code,
     description,

/*-- Admin data --*/
     @Semantics.user.createdBy: true
     created_by,
     @Semantics.systemDateTime.createdAt: true
     created_at,
     @Semantics.user.lastChangedBy: true
     last_changed_by,
     @Semantics.systemDateTime.lastChangedAt: true
     last_changed_at,

     /* Public associations */
     _Agency,
     _Customer,
     _Currency
}

然後建立一個projection view，將該view的欄位有選擇性地暴露出來。

@EndUserText.label: 'Travel projection view - Processor'
@AccessControl.authorizationCheck: #NOT_REQUIRED

@UI: {
 headerInfo: { typeName: 'Travel', typeNamePlural: 'Travels', title: { type: #STANDARD, value: 'TravelID' } } }

@Search.searchable: true

define root view entity ZC_TRAVEL_JERRY as projection on ZI_TRAVEL_JERRY {
 @UI.facet: [ { id:              'Travel',
                purpose:         #STANDARD,
                type:            #IDENTIFICATION_REFERENCE,
                label:           'Travel',
                position:        10 } ]

 @UI: {
     lineItem:       [ { position: 10, importance: #HIGH } ],
     identification: [ { position: 10, label: 'Travel ID [1,...,99999999]' } ] }
 @Search.defaultSearchElement: true
 key travel_id          as TravelID,

 @UI: {
     lineItem:       [ { position: 20, importance: #HIGH } ],
     identification: [ { position: 20 } ],
     selectionField: [ { position: 20 } ] }
 @Consumption.valueHelpDefinition: [{ entity : {name: '/DMO/I_Agency', element: 'AgencyID'  } }]

 @ObjectModel.text.element: ['AgencyName'] ----meaning?
 @Search.defaultSearchElement: true
 agency_id          as AgencyID, _Agency.Name       as AgencyName,

 @UI: {
     lineItem:       [ { position: 30, importance: #HIGH } ],
     identification: [ { position: 30 } ],
     selectionField: [ { position: 30 } ] }
 @Consumption.valueHelpDefinition: [{ entity : {name: '/DMO/I_Customer', element: 'CustomerID'  } }]

 @ObjectModel.text.element: ['CustomerName']
 @Search.defaultSearchElement: true
 customer_id        as CustomerID,

 @UI.hidden: true
 _Customer.LastName as CustomerName,

 @UI: {
     lineItem:       [ { position: 40, importance: #MEDIUM } ],
     identification: [ { position: 40 } ] }
 begin_date         as BeginDate,

 @UI: {
     lineItem:       [ { position: 41, importance: #MEDIUM } ],
     identification: [ { position: 41 } ] }
 end_date           as EndDate,

 @UI: {
     lineItem:       [ { position: 50, importance: #MEDIUM } ],
     identification: [ { position: 50, label: 'Total Price' } ] }
 @Semantics.amount.currencyCode: 'CurrencyCode'
 total_price        as TotalPrice,

 @Consumption.valueHelpDefinition: [{entity: {name: 'I_Currency', element: 'Currency' }}]
 currency_code      as CurrencyCode,

 @UI.identification: [ { position: 60, label: 'Remarks' } ]
 description as Description,

 @UI.hidden: true
 last_changed_at    as LastChangedAt

 }

大家可以注意到，這個projection view裡包含了很多@UI註解，作用和Fiori Elements一樣，作為元資料，告訴對應的渲染框架，執行時這些欄位應該以什麼樣的方式渲染在Fiori UI上。

(3) 現在三大支柱之一的Core Data Service已經就位了，接下來我們基於前一步得到的projection view建立Business Service. 選中projection view，右鍵選擇New Service Definition：

這個服務定義的第一條記錄，就是通過ABAP expose關鍵字把projection view ZC_TRAVEL_JERRY暴露出來，模型名稱為TravelProcessor：

@EndUserText.label: 'Service Defintion for ZC_Travel_JERRY'
define service ZUI_C_TRAVEL_JERRY {
  expose ZC_TRAVEL_JERRY as TravelProcessor;
  expose /DMO/I_Customer as Passenger;
  expose /DMO/I_Agency as TravelAgency;
  expose /DMO/I_Airport as Airport;
  expose I_Currency as Currency;
  expose I_Country as Country;
}

然後基於這個Service Definition建立一個Service Binding，可以簡單把Service Binding理解成Service Definition的一個例項：

Service Binding建立完畢後，點選Activate啟用：

之前Service Definition裡用expose關鍵字暴露並指定成的模型TravelProcessor此時就可見了，雙擊：

雙擊後會自動開啟一個連結，一個Fiori應用就呈現在我們眼前了。我們沒有進行一行的JavaScript web程式設計，就得到了一個專業的支援高階搜尋的Fiori應用，能檢視底層資料庫表ZTRAVEL_JERRY的內容。

(4) 至此我們已經瞭解了Restful ABAP Programming模型的前兩大支柱，還剩下Behavior Definition. 既然RAP的口號是打造具有Restful特性的應用，但到目前為止我們還沒有感受到RAP對Restful的支援，這有待Behavior Definition來完成。

選中之前建立的CDS view，建立一個新的Behavior Definition：