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Fix Query sorting of DateTimes and Decimals #392

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Fix Query sorting of DateTimes and Decimals #392

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c019c2f
Use comparison functions for Query sorting
dehall Oct 22, 2026
7f58f87
Explicitly order less-precise DateTimes first
dehall Oct 22, 2026
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56 changes: 33 additions & 23 deletions src/elm/query.ts
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import { Context } from '../runtime/context';
import { equals, greaterThan, lessThan } from '../util/comparison';
import { allTrue, asyncMergeSort, Direction, typeIsArray } from '../util/util';
import { build } from './builder';
import { Expression, UnimplementedExpression } from './expression';
Expand Down Expand Up @@ -62,6 +63,36 @@ export class Without extends With {
// ELM-only, not a product of CQL
export class Sort extends UnimplementedExpression {}

function order(a: any, b: any, low_order: number, high_order: number): number {
if (a == null || b == null) {
if (a == null && b == null) {
return 0;
}
// "When the data being sorted includes nulls, they are sorted first, meaning they will appear at the beginning of the list when the data is sorted ascending,
// and at the end of the list when the data is sorted descending."
return a == null ? low_order : high_order;
} else if (equals(a, b)) {
return 0;
} else if (lessThan(a, b)) {
return low_order;
} else if (greaterThan(a, b)) {
return high_order;
} else {
// Indeterminate, for example comparing DateTimes of different precision.
// The spec doesn't clearly say what to do here (see https://github.com/cqframework/cql-tests/issues/168 ) so the heuristics below are an implementation decision.

if (typeof a.getPrecisionValue === 'function' && typeof b.getPrecisionValue === 'function') {
// Order DateTimes with lower precision first.
// Comparison functions above internally convert DateTimes to the same timezone, so if we get here, we know any timezone difference doesn't impact the result
return order(a.getPrecisionValue(), b.getPrecisionValue(), low_order, high_order);
}

// Fallback to the plain JS operators, which coerce objects to primitives, likely strings: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Less_than
// This is imperfect but at least sorts symmetrically (a < b is always true or false, and a < b always implies b > a)
return a < b ? low_order : high_order;
}
}

export class ByDirection extends Expression {
direction: Direction;
low_order: number;
Expand All @@ -76,19 +107,7 @@ export class ByDirection extends Expression {

// @ts-ignore
async exec(ctx: Context, a: any, b: any) {
if (a === b) {
return 0;
} else if (a.isQuantity && b.isQuantity) {
if (a.before(b)) {
return this.low_order;
} else {
return this.high_order;
}
} else if (a < b) {
return this.low_order;
} else {
return this.high_order;
}
return order(a, b, this.low_order, this.high_order);
}
}

Expand All @@ -112,16 +131,7 @@ export class ByExpression extends Expression {
const a_val = await this.expression.execute(sctx);
sctx = ctx.childContext(b);
const b_val = await this.expression.execute(sctx);

if (a_val === b_val || (a_val == null && b_val == null)) {
return 0;
} else if (a_val == null || b_val == null) {
return a_val == null ? this.low_order : this.high_order;
} else if (a_val.isQuantity && b_val.isQuantity) {
return a_val.before(b_val) ? this.low_order : this.high_order;
} else {
return a_val < b_val ? this.low_order : this.high_order;
}
return order(a_val, b_val, this.low_order, this.high_order);
}
}

Expand Down
33 changes: 33 additions & 0 deletions test/elm/query/data.cql
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Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,39 @@ define sortByExpressionWithNullResults: ({8, null, 7}) N return Tuple{N: N} sort
define sortWithAscendingKeyword: ({8, 6, 7, 5, 3, 0, 9}) N sort ascending
define sortWithDescendingKeyword: ({8, 6, 7, 5, 3, 0, 9}) N return N sort descending

define Newest: Last(({ Tuple { id: 'older 05:00Z', d: @2025-01-02T05:00:00.000Z }, Tuple { id: 'newer 06:00Z', d: @2025-01-01T20:00:00.000-10:00 } }) X sort by d).id
define NewestReversedInput: Last(({ Tuple { id: 'newer 06:00Z', d: @2025-01-01T20:00:00.000-10:00 }, Tuple { id: 'older 05:00Z', d: @2025-01-02T05:00:00.000Z } }) X sort by d).id
define DateTimeDirectionAsc: ({ @2025-01-02T05:00:00.000Z, @2025-01-01T20:00:00.000-10:00 }) X sort asc
define DateTimeDirectionDesc: ({ @2025-01-02T05:00:00.000Z, @2025-01-01T20:00:00.000-10:00 }) X sort desc
define DateTimeColumnAsc: ({ Tuple { value: @2025-01-02T05:00:00.000Z }, Tuple { value: @2025-01-01T20:00:00.000-10:00 } }) X sort by value asc
define DateTimeColumnDesc: ({ Tuple { value: @2025-01-02T05:00:00.000Z }, Tuple { value: @2025-01-01T20:00:00.000-10:00 } }) X sort by value desc
define DateTimeExpressionAsc: ({ Tuple { value: @2025-01-02T05:00:00.000Z }, Tuple { value: @2025-01-01T20:00:00.000-10:00 } }) X sort by (value + 0 days) asc
define DateTimeExpressionDesc: ({ Tuple { value: @2025-01-02T05:00:00.000Z }, Tuple { value: @2025-01-01T20:00:00.000-10:00 } }) X sort by (value + 0 days) desc
define DateTimeDirectionAscReversed: ({ @2025-01-01T20:00:00.000-10:00, @2025-01-02T05:00:00.000Z }) X sort asc
define DateTimeDirectionDescReversed: ({ @2025-01-01T20:00:00.000-10:00, @2025-01-02T05:00:00.000Z }) X sort desc
define DateTimeColumnAscReversed: ({ Tuple { value: @2025-01-01T20:00:00.000-10:00 }, Tuple { value: @2025-01-02T05:00:00.000Z } }) X sort by value asc
define DateTimeColumnDescReversed: ({ Tuple { value: @2025-01-01T20:00:00.000-10:00 }, Tuple { value: @2025-01-02T05:00:00.000Z } }) X sort by value desc
define DateTimeExpressionAscReversed: ({ Tuple { value: @2025-01-01T20:00:00.000-10:00 }, Tuple { value: @2025-01-02T05:00:00.000Z } }) X sort by (value + 0 days) asc
define DateTimeExpressionDescReversed: ({ Tuple { value: @2025-01-01T20:00:00.000-10:00 }, Tuple { value: @2025-01-02T05:00:00.000Z } }) X sort by (value + 0 days) desc
// The hour-precision value spans 07:00Z–07:59:59.999Z, entirely after 05:30Z.
define DateTimeMixedPrecisionAsc: ({ @2025-01-02T05:30:00.000Z, @2025-01-02T05-02:00 }) X sort asc
define DateTimeMixedPrecisionAscReversed: ({ @2025-01-02T05-02:00, @2025-01-02T05:30:00.000Z }) X sort asc
// 05-02:00 spans 07:00Z–07:59:59.999Z and overlaps the precise 07:30Z instant.
define DateTimeIndeterminatePrecisionAsc: ({ @2025-01-02T07:30:00.000Z, @2025-01-02T05-02:00 }) X sort asc
define DateTimeIndeterminatePrecisionAscReversed: ({ @2025-01-02T05-02:00, @2025-01-02T07:30:00.000Z }) X sort asc
define DecimalDirectionAsc: ({ 2.5, 10.25 }) X sort asc
define DecimalDirectionDesc: ({ 2.5, 10.25 }) X sort desc
define DecimalColumnAsc: ({ Tuple { value: 2.5 }, Tuple { value: 10.25 } }) X sort by value asc
define DecimalColumnDesc: ({ Tuple { value: 2.5 }, Tuple { value: 10.25 } }) X sort by value desc
define DecimalExpressionAsc: ({ Tuple { value: 2.5 }, Tuple { value: 10.25 } }) X sort by (value + 0.0) asc
define DecimalExpressionDesc: ({ Tuple { value: 2.5 }, Tuple { value: 10.25 } }) X sort by (value + 0.0) desc
define DecimalDirectionAscReversed: ({ 10.25, 2.5 }) X sort asc
define DecimalDirectionDescReversed: ({ 10.25, 2.5 }) X sort desc
define DecimalColumnAscReversed: ({ Tuple { value: 10.25 }, Tuple { value: 2.5 } }) X sort by value asc
define DecimalColumnDescReversed: ({ Tuple { value: 10.25 }, Tuple { value: 2.5 } }) X sort by value desc
define DecimalExpressionAscReversed: ({ Tuple { value: 10.25 }, Tuple { value: 2.5 } }) X sort by (value + 0.0) asc
define DecimalExpressionDescReversed: ({ Tuple { value: 10.25 }, Tuple { value: 2.5 } }) X sort by (value + 0.0) desc

// @Test: Distinct
define defaultNumbers: ({1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 3, 3, 3, 2, 2, 1}) N return N
define defaultStrings: ({'foo', 'bar', 'baz', 'bar'}) S return S
Expand Down
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