BOSS

Environment Setup
boss module create -m <module1> <pkg1>
boss bo create -bo Inv -t ap_invoices_all -m module1 pkg1
boss bo create -bo InvLine -t ap_invoice_lines_all -m module1 pkg1
boss bo addrelation -m module1 -bo Inv -tbo InvLine -fm invoiceId:invoiceId -c OneToMany -acc lines -macc invoice pkg1
boss view create default -m module1 -bo Inv pkg1
boss view create -m moduleName -bo BusinessObjectName -v viewName <app-package-name>
Create transient atributes, mark attributes as sortable, searchable.
Deploying
cd pkg1/sources
vi app-package.json5
{
name: "pkg1",
version: "1.0.0",
description: "ERPM spectra training app",
dependencies: { }
}
cd $BOSS_MODEL_HOME/config
vi application.json
[
{
"id": "ora_erp_expenses",
"name": "ERPM spectra training app",
"version": "1.0.0",
"description": "ERPM spectra training app",
"repositories": {
"factory": "file:///factory"
},
"appPackages": {
"ora_erp_expenses": {
"repository": "factory",
"version": "=1.0.0"
}
},
"services": {
"boss": {
"version": ">=1.0.0"
}
}
}
]
boss metadata package -a pkg1
curl -vLk --noproxy "*" -u jack:password -X POST 'http://localhost:8000/api/rwdinfra/apm/v1/applications?force=Enabled' -d @$BOSS_MODEL_HOME/config/application.json

Testing

curl --location --request GET 'http://<host>:<port>/api/boss/data/objects/oraErpExpenses/v1:<deployment_id>/$openapi/expenses' --header 'Authorization: Basic c3VwZXJfdXNlcjp3ZWxjb21lMQ=='
http://mumbai242698.bom2.fusionappsdbom1.oraclevcn.com:8000/api/boss/data/objects/module1/v1:1/$openapi/inv

curl --location --request GET 'http://<host>:<port>/api/boss/data/objects/oraErpExpenses/v1:<deployment_id>/expenses' --header 'Authorization: Basic c3VwZXJfdXNlcjp3ZWxjb21lMQ=='
http://mumbai242698.bom2.fusionappsdbom1.oraclevcn.com:8000/api/boss/data/objects/module1/v1:1/inv

package oraErpExpenses.expense.triggers;

import oracle.boss.script.BeforeReadContext;
import oracle.boss.script.annotation.BeforeRead;

public final class ExpenseBeforeReadTrigger {

    @BeforeRead
    public static void beforeRead(final BeforeReadContext context) {
        context.logger().info("In expense.ExpenseBeforeReadTrigger::beforeRead:START");
        context.logger().info("In expense.ExpenseBeforeReadTrigger::beforeRead:END");
    }
}
expenseTypeName : { type : "string", accessModifier : "public", readable : "public", nullable : true, creatable : "module", updatable : "module", fieldSecurityEnabled : false },

Query over POST is technique through which any fetch request with a complicated filter, sort , paging or shaping criteria including parent & child objects can be formulated as json request body over a POST request, provided we use $query endpoint. The json structure used for QueryOverPost to define the fields/filter/sort/pagination criteria is very similar to how we define Business views . But these are not saved with the rest of the BO metadata.
Initialise Parameters For NamedViews
    "expenseId",
    "expenseTypeId",
    "description",
    "location",
    "receiptAmount",
    "receiptCurrencyCode",
    "reimbursableAmount",
    "reimbursementCurrencyCode",
    "expenseDate"
  ],
  accessors: {
    expenseType: {
      fields: [
        "expenseTypeId",
        "name"
      ]
    },
  },
  parameters: {
    formOfPaymentsParam: {
      type: "string"
    },
    expSourceParam: {
      type: "string"
    }
  },
  collection: {
    sortBy: [
      { "reimbursableAmount" : "desc" } ,
      { "expenseDate" : "asc" },
      { "expenseCategoryCodeOrder": "asc"},
      { "timeCreated" : "desc" }
    ],
    filter : "personId != NULL AND expenseReportId = NULL AND (validationStatusCode=NULL OR validationStatusCode in ('CLEAN')) AND expenseSource='CASH'"
  }
}
fields :

Define FND Lookup Based LOVs With Translations
Uptake Fndlookup Based References For flightclass, flighttype & formOfPayments LOV
Enum Based Lists