fix: Treat assoc-like calculated elements as unmanaged assocs (#830)

Association like calculated elements have been re-written by the
compiler they essentially behave like unmanaged associations as their
calculations have been incorporated into an on-condition which is
handled elsewhere

→ We don't need to treat them any different than a regular unmanaged
association.

db-service/lib/cqn4sql.js

@@ -4,7 +4,7 @@ const cds = require('@sap/cds')
 
 const infer = require('./infer')
 const { computeColumnsToBeSearched } = require('./search')
-const { prettyPrintRef } = require('./utils')
+const { prettyPrintRef, isCalculatedOnRead } = require('./utils')
 
 /**
  * For operators of <eqOps>, this is replaced by comparing all leaf elements with null, combined with and.
@@ -317,10 +317,6 @@ function cqn4sql(originalQuery, model) {
     }
   }
 
-  function isCalculatedOnRead(def) {
-    return def?.value && !def.value.stored
-  }
-
   /**
    * Walks over a list of columns (ref's, xpr, subqueries, val), applies flattening on structured types and expands wildcards.
    *

db-service/lib/infer/index.js

@@ -4,6 +4,7 @@ const cds = require('@sap/cds')
 
 const JoinTree = require('./join-tree')
 const { pseudos } = require('./pseudos')
+const { isCalculatedOnRead } = require('../utils')
 const cdsTypes = cds.linked({
   definitions: {
     Timestamp: { type: 'cds.Timestamp' },
@@ -746,7 +747,7 @@ function infer(originalQuery, model) {
           joinTree.mergeColumn(colWithBase, originalQuery.outerQueries)
         }
       }
-      if (leafArt.value && !leafArt.value.stored) {
+      if (isCalculatedOnRead(leafArt)) {
         linkCalculatedElement(column, $baseLink, baseColumn)
       }
 
@@ -1054,7 +1055,7 @@ function infer(originalQuery, model) {
             if (element.type !== 'cds.LargeBinary') {
               queryElements[k] = element
             }
-            if (element.value) {
+            if (isCalculatedOnRead(element)) {
               linkCalculatedElement(element)
             }
           }
@@ -1071,7 +1072,7 @@ function infer(originalQuery, model) {
         if (exclude(name) || name in queryElements) return true
         const element = tableAliases[0].tableAlias.elements[name]
         if (element.type !== 'cds.LargeBinary') queryElements[name] = element
-        if (element.value) {
+        if (isCalculatedOnRead(element)) {
           linkCalculatedElement(element)
         }
       })

db-service/lib/utils.js

@@ -21,7 +21,22 @@ function prettyPrintRef(ref, model = null) {
   }, '')
 }
 
+/**
+ * Determines if a definition is calculated on read.
+ * - Stored calculated elements are not unfolded
+ * - Association like calculated elements have been re-written by the compiler
+ *   they essentially behave like unmanaged associations as their calculations
+ *   have been incorporated into an on-condition which is handled elsewhere
+ *
+ * @param {Object} def - The definition to check.
+ * @returns {boolean} - Returns true if the definition is calculated on read, otherwise false.
+ */
+function isCalculatedOnRead(def) {
+  return def?.value && !def.value.stored && !def.on
+}
+
 // export the function to be used in other modules
 module.exports = {
   prettyPrintRef,
+  isCalculatedOnRead
 }

db-service/test/bookshop/db/booksWithExpr.cds

@@ -79,7 +79,7 @@ entity LBooks {
   key ID : Integer;
 
   title : localized String;
-  ctitle = substring(title, 3, 3);  // requires compiler 4.1
+  ctitle = substring(title, 3, 3);
 
   length : Decimal;
   width : Decimal;
@@ -92,3 +92,10 @@ entity Simple {
   my: Association to Simple;
   myName: String = my.name;
 }
+
+entity VariableReplacements {
+  key ID: Integer;
+  author: Association to Authors;
+  // with variable replacements
+  authorAlive = author[dateOfBirth <= $now and dateOfDeath >= $now];
+}

db-service/test/cqn4sql/calculated-elements.test.js

@@ -968,6 +968,26 @@ describe('Unfolding calculated elements in other places', () => {
     }`
     expect(query).to.deep.equal(expected)
   })
+  it('variable replacements are left untouched in calc element navigation', () => {
+    const q = CQL`SELECT from booksCalc.VariableReplacements { ID, authorAlive.firstName }`
+    const expected = CQL`SELECT from booksCalc.VariableReplacements as VariableReplacements
+    left join booksCalc.Authors as authorAlive on ( authorAlive.ID = VariableReplacements.author_ID )
+    and ( authorAlive.dateOfBirth <= $now and authorAlive.dateOfDeath >= $now )
+    {
+        VariableReplacements.ID,
+        authorAlive.firstName as authorAlive_firstName
+    }`
+    expect(cqn4sql(q, model)).to.deep.equal(expected)
+  })
+  it('variable replacements are left untouched in calc elements via wildcard', () => {
+    const q = CQL`SELECT from booksCalc.VariableReplacements { * }`
+    const expected = CQL`SELECT from booksCalc.VariableReplacements as VariableReplacements
+    {
+        VariableReplacements.ID,
+        VariableReplacements.author_ID
+    }`
+    expect(cqn4sql(q, model)).to.deep.equal(expected)
+  })
 })
 
 describe('Unfolding calculated elements ... misc', () => {
@@ -1002,7 +1022,6 @@ describe('Unfolding calculated elements and localized', () => {
     expect(query).to.deep.equal(expected)
   })
 
-  // enable once cds-compiler v4.1 is released
   it('calculated element refers to localized element', () => {
     const q = CQL`SELECT from booksCalc.LBooks { ID, title, ctitle }`
     q.SELECT.localized = true