feat(firestore): [PQ] add consistency selector

[bhshkh]

Add consistency selector similar to existing requests

Existing code for reference:

client.go :

google-cloud-go/firestore/client.go

Lines 405 to 412 in 66cc9bb

	// WithReadOptions specifies constraints for accessing documents from the database,
	// e.g. at what time snapshot to read the documents.
	func (c *Client) WithReadOptions(opts ...ReadOption) *Client {
	for _, ro := range opts {
	ro.apply(c.readSettings)
	}
	return c
	}

google-cloud-go/firestore/client.go

Lines 308 to 317 in 66cc9bb

	// Note that transaction ID and other consistency selectors are mutually exclusive.
	// We respect the transaction first, any read options passed by the caller second,
	// and any read options stored in the client third.
	if rt, hasOpts := parseReadTime(c, rs); hasOpts {
	req.ConsistencySelector = &pb.BatchGetDocumentsRequest_ReadTime{ReadTime: rt}
	}
	if tid != nil {
	req.ConsistencySelector = &pb.BatchGetDocumentsRequest_Transaction{Transaction: tid}
	}

google-cloud-go/firestore/client.go

Lines 490 to 504 in 66cc9bb

	// ReadTime specifies a time-specific snapshot of the database to read.
	func ReadTime(t time.Time) ReadOption {
	return readTime(t)
	}
	type readTime time.Time
	func (rt readTime) apply(rs *readSettings) {
	rs.readTime = time.Time(rt)
	}
	// ReadOption interface allows for abstraction of computing read time settings.
	type ReadOption interface {
	apply(*readSettings)
	}

query.go :

google-cloud-go/firestore/query.go

Lines 1406 to 1412 in 66cc9bb

	// Respect transactions first and read options (read time) second
	if rt, hasOpts := parseReadTime(client, it.readSettings); hasOpts {
	req.ConsistencySelector = &pb.RunQueryRequest_ReadTime{ReadTime: rt}
	}
	if it.tid != nil {
	req.ConsistencySelector = &pb.RunQueryRequest_Transaction{Transaction: it.tid}
	}

google-cloud-go/firestore/query.go

Lines 1551 to 1561 in 66cc9bb

	// WithReadOptions specifies constraints for accessing documents from the database,
	// e.g. at what time snapshot to read the documents.
	func (q *Query) WithReadOptions(opts ...ReadOption) *Query {
	if q.readSettings == nil {
	q.readSettings = &readSettings{}
	}
	for _, ro := range opts {
	ro.apply(q.readSettings)
	}
	return q
	}

list_documents.go :

google-cloud-go/firestore/list_documents.go

Lines 48 to 55 in 66cc9bb

	// Transactions and ReadTime are mutually exclusive; Transactions should be
	// respected before read time.
	if rt, hasOpts := parseReadTime(client, rs); hasOpts {
	req.ConsistencySelector = &pb.ListDocumentsRequest_ReadTime{ReadTime: rt}
	}
	if tid != nil {
	req.ConsistencySelector = &pb.ListDocumentsRequest_Transaction{Transaction: tid}
	}

Previous pull requests

• feat(firestore): [PQ] add pipeline queries #12217
• feat(firestore): [PQ] Add rest of the input stages #12425
• feat(firestore): [PQ] Add pipeline expressions basic structure #12538
• feat(firestore): [PQ] add all the remaining arithmetic and comparison functions #13147
• test(firestore): [PQ] Modify integration test to run on enterprise db #13199
• feat(firestore): [PQ] add all the remaining private preview stages #13218
• feat(firestore): [PQ] Add all Aggregation and Timestamp functions #13194
• feat(firestore): [PQ] add all array, string and vector functions #13245
• test(firestore): [PQ] move tests and resolve build failures #13270
• refactor(firestore): [PQ] Combine FieldOf and FieldOfPath #13271
• refactor(firestore): [PQ] Remove types functions #13279
• feat(firestore): [PQ] add raw stage #13280
• feat(firestore): [PQ] add collection stage options #13281

[bhshkh]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds support for consistency selectors to Firestore pipelines, including WithReadOptions and execution within transactions. The changes are logical and include necessary integration tests. I have a couple of suggestions for firestore/pipeline.go to improve code clarity and remove a redundant check.