fix(i): Aggregate json filter (#3150)

## Relevant issue(s)

Resolves #3149

## Description

This PR fixes an issue with aggregate JSON filtering.

## Tasks

- [x] I made sure the code is well commented, particularly
hard-to-understand areas.
- [x] I made sure the repository-held documentation is changed
accordingly.
- [x] I made sure the pull request title adheres to the conventional
commit style (the subset used in the project can be found in
[tools/configs/chglog/config.yml](tools/configs/chglog/config.yml)).
- [x] I made sure to discuss its limitations such as threats to
validity, vulnerability to mistake and misuse, robustness to
invalidation of assumptions, resource requirements, ...

## How has this been tested?

Added integration test.

Specify the platform(s) on which this was tested:
- MacOS

internal/planner/mapper/mapper.go

@@ -439,6 +439,7 @@ func resolveAggregates(
 				if err != nil {
 					return nil, err
 				}
+				removeJSONSubFields(childMapping, hostSelectRequest)
 
 				childFields, _, err := getRequestables(
 					ctx,
@@ -569,6 +570,32 @@ func resolveAggregates(
 	return fields, nil
 }
 
+// removeJSONSubFields ensures that selections of
+// JSON objects are not interpreted as joins.
+//
+// This can happen when an aggregate contains a filter
+// on a JSON object, but we can't tell if it is a relation
+// until the child mapping is created.
+func removeJSONSubFields(
+	mapping *core.DocumentMapping,
+	hostSelectRequest *request.Select,
+) {
+	var fields []request.Selection
+	for _, field := range hostSelectRequest.Fields {
+		switch f := field.(type) {
+		case *request.Select:
+			_, isMapped := mapping.IndexesByName[f.Name]
+			if !isMapped {
+				fields = append(fields, field)
+			}
+
+		default:
+			fields = append(fields, field)
+		}
+	}
+	hostSelectRequest.Fields = fields
+}
+
 func mapAggregateNestedTargets(
 	target *aggregateRequestTarget,
 	hostSelectRequest *request.Select,

tests/integration/query/json/with_aggregate_test.go

@@ -0,0 +1,65 @@
+// Copyright 2024 Democratized Data Foundation
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package json
+
+import (
+	"testing"
+
+	testUtils "github.com/sourcenetwork/defradb/tests/integration"
+)
+
+func TestQueryJSON_WithAggregateFilter_Succeeds(t *testing.T) {
+	test := testUtils.TestCase{
+		Description: "Simple JSON, aggregate with filter",
+		Actions: []any{
+			testUtils.SchemaUpdate{
+				Schema: `type Users {
+					name: String
+					custom: JSON
+				}`,
+			},
+			testUtils.CreateDoc{
+				Doc: `{
+					"name": "John",
+					"custom": {
+						"tree": "maple",
+						"age": 250
+					}
+				}`,
+			},
+			testUtils.CreateDoc{
+				Doc: `{
+					"name": "Andy",
+					"custom": {
+						"tree": "oak",
+						"age": 450
+					}
+				}`,
+			},
+			testUtils.CreateDoc{
+				Doc: `{
+					"name": "Shahzad",
+					"custom": null
+				}`,
+			},
+			testUtils.Request{
+				Request: `query {
+					_count(Users: {filter: {custom: {tree: {_eq: "oak"}}}})
+				}`,
+				Results: map[string]any{
+					"_count": 1,
+				},
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}

tests/integration/query/one_to_many/with_count_filter_test.go

@@ -178,3 +178,86 @@ func TestQueryOneToManyWithCountWithFilterAndChildFilter(t *testing.T) {
 
 	executeTestCase(t, test)
 }
+
+func TestQueryOneToMany_WithCountWithJSONFilterAndChildFilter_Succeeds(t *testing.T) {
+	test := testUtils.TestCase{
+		Description: "One-to-many relation query from many side with count with JSON filter",
+		Actions: []any{
+			testUtils.SchemaUpdate{
+				Schema: `
+				type Book {
+					name: String
+					rating: Float
+					author: Author
+				}
+
+				type Author {
+					name: String
+					age: Int
+					verified: Boolean
+					published: [Book]
+					metadata: JSON
+				}`,
+			},
+			testUtils.CreateDoc{
+				CollectionID: 1,
+				Doc: `{
+					"name": "John Grisham",
+					"age": 65,
+					"verified": true,
+					"metadata": {
+						"yearOfBirth": 1955
+					}
+				}`,
+			},
+			testUtils.CreateDoc{
+				CollectionID: 1,
+				Doc: `{
+					"name": "Cornelia Funke",
+					"age": 62,
+					"verified": false,
+					"metadata": {
+						"yearOfBirth": 1958
+					}
+				}`,
+			},
+			testUtils.CreateDoc{
+				CollectionID: 0,
+				DocMap: map[string]any{
+					"name":      "Painted House",
+					"rating":    4.9,
+					"author_id": testUtils.NewDocIndex(1, 0),
+				},
+			},
+			testUtils.CreateDoc{
+				CollectionID: 0,
+				DocMap: map[string]any{
+					"name":      "A Time for Mercy",
+					"rating":    4.5,
+					"author_id": testUtils.NewDocIndex(1, 0),
+				},
+			},
+			testUtils.CreateDoc{
+				CollectionID: 0,
+				DocMap: map[string]any{
+					"name":      "Theif Lord",
+					"rating":    4.8,
+					"author_id": testUtils.NewDocIndex(1, 1),
+				},
+			},
+			testUtils.Request{
+				Request: `query {
+					_count(Author: {filter: {
+						metadata: {yearOfBirth: {_eq: 1958}},
+						published: {name: {_ilike: "%lord%"}}
+					}})
+				}`,
+				Results: map[string]any{
+					"_count": 1,
+				},
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}