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fix(firestore): ensure limit(0) is properly serialized in query requests #8076

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fix(firestore): ensure limit(0) is properly serialized in query requests #8076

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e7f1b6f
fix(firestore): ensure limit(0) is properly serialized in query requests
liu-husong Dec 16, 2025
d8aecde
test(firestore): add regression test for limit(0) serialization
liu-husong Dec 16, 2025
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2 changes: 1 addition & 1 deletion handwritten/firestore/dev/src/reference/query-util.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -344,7 +344,7 @@ export class QueryUtil<
// call to `requestStream()` will backoff should the restart
// fail before delivering any results.
let newQuery: Query<AppModelType, DbModelType>;
if (!this._queryOptions.limit) {
if (this._queryOptions.limit === undefined) {
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@gemini-code-assist gemini-code-assist Bot Apr 20, 2026

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medium

The check this._queryOptions.limit === undefined correctly allows 0 to be processed in the else block, but it changes the behavior for null values. Previously, null was treated as "no limit" (entering the if block), but now it will proceed to the else block. To maintain the existing behavior for null while fixing it for 0, consider using a nullish check (== null), which is the recommended way to check for both null and undefined in the Google TypeScript Style Guide.

Suggested change
if (this._queryOptions.limit === undefined) {
if (this._queryOptions.limit == null) {
References
  1. The Google TypeScript Style Guide recommends using == null to check for both null and undefined. (link)

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@liu-husong liu-husong Apr 20, 2026

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limit is typed as number | undefined. So null shouldn't be a valid value.

newQuery = query;
} else {
const newLimit =
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2 changes: 1 addition & 1 deletion handwritten/firestore/dev/src/reference/query.ts
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Expand Up @@ -1608,7 +1608,7 @@ export class Query<
structuredQuery.startAt = this.toCursor(this._queryOptions.startAt);
structuredQuery.endAt = this.toCursor(this._queryOptions.endAt);

if (this._queryOptions.limit) {
if (this._queryOptions.limit !== undefined) {
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@gemini-code-assist gemini-code-assist Bot Apr 20, 2026

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medium

Using !== undefined here will cause null values to be serialized as {value: null}, which may lead to errors during proto serialization if the field expects a numeric value. Using != null ensures that only non-nullish values (including 0) are serialized, preserving the original behavior for null while fixing the issue for 0. This aligns with the Google TypeScript Style Guide's recommendation for nullish checks.

Suggested change
if (this._queryOptions.limit !== undefined) {
if (this._queryOptions.limit != null) {
References
  1. The Google TypeScript Style Guide recommends using != null to check for both null and undefined. (link)

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@liu-husong liu-husong Apr 20, 2026

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limit is typed as number | undefined. So null shouldn't be a valid value.

structuredQuery.limit = {value: this._queryOptions.limit};
}

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14 changes: 14 additions & 0 deletions handwritten/firestore/dev/test/query.ts
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Expand Up @@ -1957,6 +1957,20 @@ describe('limit() interface', () => {
query = query.limit(1).limit(2).limit(3);
await query.get();
});

it('handles limit(0) correctly', async () => {
const overrides: ApiOverride = {
runQuery: request => {
queryEquals(request, limit(0));
return emptyQueryStream();
},
};

firestore = await createInstance(overrides);
let query: Query = firestore.collection('collectionId');
query = query.limit(0);
await query.get();
});
});

describe('limitToLast() interface', () => {
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