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Fix query on size of a single link over links #6918

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merged 2 commits into from
Aug 24, 2023
Merged

Fix query on size of a single link over links #6918

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a6a84f1
Fix query on size of a single link over links
jedelbo Aug 23, 2023
912c73a
Rephrase release note
jedelbo Aug 23, 2023
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2 changes: 1 addition & 1 deletion CHANGELOG.md
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Expand Up @@ -6,7 +6,7 @@

### Fixed
* <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)
* None.
* Crash when querying the size of a Object property through a link chain ([#6915](https://github.com/realm/realm-core/issues/6915), since v13.17.2)

### Breaking changes
* None.
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7 changes: 6 additions & 1 deletion src/realm/query_expression.cpp
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Expand Up @@ -519,11 +519,16 @@ void LinkCount::evaluate(size_t index, ValueBase& destination)
const Obj obj = m_link_map.get_target_table()->get_object(links[i]);
auto val = obj._get<int64_t>(m_column_key.get_index());
size_t s;
if (val & 1) {
if (m_column_key.get_type() == col_type_Link && !m_column_key.is_collection()) {
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Do I read this correctly? You are trying to avoid to deal with collections of links? Right?

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Yes. We must handle single link columns separately. That was the problem.

// It is a single link column
s = (val == 0) ? 0 : 1;
}
else if (val & 1) {
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How can you be sure that, at this point, we are dealing with a simple backlink column that points to one value? I guess what I am trying to say, is that... the logic behind val == 0 vs val == 1 is a little bit obscure, does val represents a simple boolean flag?....

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Maybe a bit obscure. The only case where we can have a tagged value here is when we are dealing with a backlink column with a single link. All other cases we have a ref to bplustree of links.

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OK maybe we can use a comment here. Describing this.

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There is actually a comment

// It is a backlink column with just one value
s = 1;
}
else {
// This is some kind of collection or backlink column
s = _impl::get_collection_size_from_ref(to_ref(val), alloc);
}
destination.set(i, int64_t(s));
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13 changes: 12 additions & 1 deletion test/test_query.cpp
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Expand Up @@ -5640,6 +5640,7 @@ TEST(Query_NestedLinkCount)
table->add_column_list(*table, "children");
table->add_column_dictionary(*table, "dictionary");
table->add_column_list(*table, "list");
table->add_column(*table, "Object");

Obj o1 = table->create_object_with_primary_key(1);
Obj o2 = table->create_object_with_primary_key(2);
Expand All @@ -5650,6 +5651,10 @@ TEST(Query_NestedLinkCount)
dict.insert("key", o3);
o3.get_linklist("children").add(o2.get_key());

o1.set("Object", o1.get_key());
o2.set("Object", o2.get_key());
o3.set("Object", o2.get_key());

auto q = table->query("children.list.@size == 0");
CHECK_EQUAL(q.count(), 2);

Expand All @@ -5676,7 +5681,13 @@ TEST(Query_NestedLinkCount)
dict.insert("key4", o3);
q = table->query("@links.TestClass.children.dictionary.@size == 5");
CHECK_EQUAL(q.count(), 1); // Only o2
}

q = table->query("@links.TestClass.Object.@size > 0");
CHECK_EQUAL(q.count(), 2);
q = table->query("@links.TestClass.Object.Object.@size > 0");
CHECK_EQUAL(q.count(), 2);
q = table->query("Object.@links.TestClass.Object.@size > 0");
CHECK_EQUAL(q.count(), 3);
}

#endif // TEST_QUERY