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feat: query modifiers on expand ref are propagated to subquery #1049

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merged 1 commit into from
Feb 27, 2025
Merged

feat: query modifiers on expand ref are propagated to subquery #1049

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16 changes: 8 additions & 8 deletions db-service/lib/cqn4sql.js
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Original file line number Diff line number Diff line change
Expand Up @@ -807,11 +807,13 @@ function cqn4sql(originalQuery, model) {
// `SELECT from Authors { books.genre as genreOfBooks { name } } becomes `SELECT from Books:genre as genreOfBooks`
const from = { ref: subqueryFromRef, as: uniqueSubqueryAlias }
const subqueryBase = {}
for (const [key, value] of Object.entries(column)) {
if (!(key in { ref: true, expand: true })) {
subqueryBase[key] = value
}
const queryModifiers = { ...column, ...ref.at(-1) }
for (const [key, value] of Object.entries(queryModifiers)) {
if (key in { limit: 1, orderBy: 1, groupBy: 1, excluding: 1, where: 1, having: 1 }) subqueryBase[key] = value
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everything covered?

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compared with cqn2sql and lgtm.

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👍 but you can take out excluding → that is always next to expand or inline. Also in CQL syntax as supported by the compiler, and hence the CQN produced by it:

cds.ql `SELECT from Authors { ID, name, books[order by title desc limit 1] {*} excluding { descr } }`
⇒ cds.ql {
  SELECT: {
    from: { ref: [ 'Authors' ] },
    columns: [
      { ref: [ 'ID' ] },
      { ref: [ 'name' ] },
      {
        ref: [
          {
            id: 'books',
            orderBy: [ { ref: [ 'title' ], sort: 'desc' } ],
            limit: { rows: { val: 1 } }
          }
        ],
        expand: [ '*' ],
        excluding: [ 'descr' ]
      }
    ]
  }
}

}
// where at leaf already part of subqueryBase
if (from.ref.at(-1).where) from.ref[from.ref.length - 1] = [from.ref.at(-1).id]

const subquery = {
SELECT: {
...subqueryBase,
Expand Down Expand Up @@ -1225,8 +1227,7 @@ function cqn4sql(originalQuery, model) {
if (flattenThisForeignKey) {
const fkElement = getElementForRef(k.ref, getDefinition(element.target))
let fkBaseName
if (!leafAssoc || leafAssoc.onlyForeignKeyAccess)
fkBaseName = `${baseName}_${k.as || k.ref.at(-1)}`
if (!leafAssoc || leafAssoc.onlyForeignKeyAccess) fkBaseName = `${baseName}_${k.as || k.ref.at(-1)}`
// e.g. if foreign key is accessed via infix filter - use join alias to access key in target
else fkBaseName = k.ref.at(-1)
const fkPath = [...csnPath, k.ref.at(-1)]
Expand Down Expand Up @@ -1478,8 +1479,7 @@ function cqn4sql(originalQuery, model) {
// reject associations in expression, except if we are in an infix filter -> $baseLink is set
assertNoStructInXpr(token, $baseLink)
// reject virtual elements in expressions as they will lead to a sql error down the line
if(definition?.virtual)
throw new Error(`Virtual elements are not allowed in expressions`)
if (definition?.virtual) throw new Error(`Virtual elements are not allowed in expressions`)

let result = is_regexp(token?.val) ? token : copy(token) // REVISIT: too expensive! //
if (token.ref) {
Expand Down
64 changes: 64 additions & 0 deletions db-service/test/cqn4sql/expand.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,70 @@ describe('Unfold expands on associations to special subselects', () => {
expect(JSON.parse(JSON.stringify(res))).to.deep.equal(expected)
})

it('do not loose additional properties on expand column if defined in ref', () => {
const q = cds.ql`SELECT from bookshop.Authors { books[order by price] { title } }`
const res = cqn4sql(q)
const expected = CQL`SELECT from bookshop.Authors as Authors {
(
SELECT from bookshop.Books as books {
books.title
}
where Authors.ID = books.author_ID
order by books.price
) as books
}`
expect(JSON.parse(JSON.stringify(res))).to.deep.equal(expected)
})

it('query modifiers in ref have precedence over expand siblings', () => {
const q = {
SELECT: {
from: {
ref: ['bookshop.Books'],
},
columns: [
{
ref: [{id: 'author', orderBy: [{ref:['dateOfBirth'], sort: 'desc'}]}],
expand: [
{
ref: ['name'],
},
],
limit: {
offset: {
val: 1,
},
rows: {
val: 1,
},
},
// this order by is overwritten by the one in the ref
orderBy: [
{
ref: ['name'],
sort: 'asc',
},
],
},
],
},
}

const res = cqn4sql(q)
const expected = CQL`SELECT from bookshop.Books as Books {
(
SELECT from bookshop.Authors as author {
author.name
}
where Books.author_ID = author.ID
order by author.dateOfBirth desc
limit 1
offset 1
) as author
}`
expect(JSON.parse(JSON.stringify(res))).to.deep.equal(expected)
})

it('add where exists <assoc> shortcut to expand subquery where condition', () => {
const q = {
SELECT: {
Expand Down