您可以使用 returnScope 选项设立查询上下文,并将对象数组作为单个文档返回。
要求
要使用 returnScope 将嵌套对象作为独立文档检索,您必须:
将对象数组索引为 embeddedDocuments 类型。
为要检索的嵌套字段定义 storedSource。MongoDB 搜索仅返回在
storedSource中定义的字段。在查询中将 returnStoredSource 选项设置为
true。
语法
returnScope 查询中包含以下语法:
要了解有关查询语法的更多信息,请参阅$search 。
行为
returnScope 选项设置查询的检索上下文。如果您在查询中指定 returnScope,MongoDB Search 就会像处理单个文档一样对每个嵌入式文档进行评分、排序和计数。
Considerations
当您使用 returnScope 选项时,MongoDB Search 仅返回您在 embeddedDocument 中配置为 storedSource 的字段。embeddedDocument 路径之外的字段(例如根级字段)和未配置为 storedSource 的字段不会被返回。
在操作符规范中,必须指定要查询的字段的完整路径。使用 returnScope 选项时,必须确保所有操作符规范路径都嵌套在 returnScope.path 下。要查询returnScope.path 之外的字段,必须使用 hasAncestor 或 hasRoot操作符。要学习;了解详情,请参阅:
检索根文档 ID
在查询中使用 returnScope 时,MongoDB Search 会填充 searchRootDocumentId 元数据字段。您可以在运行 MongoDB 8.3 或更高版本的集群上使用 searchRootDocumentId 元数据字段。此字段包含每个返回的嵌入式文档所在的根文档的标识符。要预计此值,请将 $meta 表达式与 searchRootDocumentId 关键字一起使用。
MongoDB Search 仅当您的查询同时设置 returnStoredSource: true 和 returnScope.path 时才填充 searchRootDocumentId。如果您在查询中引用 searchRootDocumentId,但查询未指定 returnScope,则查询将失败并显示以下错误:
query requires $search root document id metadata, but it is not available
如果您想进行以下操作,请使用 searchRootDocumentId:
在对子文档进行过滤后,从父文档中获取字段。
按父文档对子文档进行分组。
如果出现以下情况,请勿使用 searchRootDocumentId:
您只需要匹配的子文档中的字段。
您希望返回结果集中每个子文档的父文档,因为这可能会很耗时。
示例
以下示例演示了如何在查询中使用 returnScope 选项。这些示例使用 sample_training.companies 示例数据集。如果您在集群上加载数据并在集合的字段上创建示例索引,则可以针对示例数据运行以下查询。
样本索引
1 { 2 "mappings": { 3 "dynamic": false, 4 "fields": { 5 "funding_rounds": { 6 "type": "embeddedDocuments", 7 "dynamic": true, 8 "fields": { 9 "investments": { 10 "type": "embeddedDocuments", 11 "dynamic": true 12 } 13 }, 14 "storedSource": { 15 "include": [ 16 "round_code", 17 "raised_currency_code", 18 "raised_amount", 19 "investments.person", 20 "investments.financial_org" 21 ] 22 } 23 } 24 } 25 } 26 }
前面的索引定义将MongoDB 搜索配置为:
将
funding_rounds和funding_rounds.investments字段作为embeddedDocuments类型进行索引。为嵌套在
funding_rounds和funding_rounds.investments对象数组中的所有可动态索引的字段建立索引。将以下字段存储在
mongot上:funding_rounds.round_codefunding_rounds.raised_currency_codefunding_rounds.raised_amountfunding_rounds.investments.personfunding_rounds.investments.financial_org
您可以使用embeddedDocument 操作符对 funding_rounds 和 funding_rounds.investments 字段进行逐元素查询。以下章节展示了一些使用 returnScope 选项将 embeddedDocuments 字段作为单独文档检索的示例查询。
{ ..., "funding_rounds": [ { "id": <integer>, "round_code": "<string>", "source_url": "<string>", "source_description": "<string>", "raised_amount": <integer>, "raised_currency_code": "<string>", "funded_year": <integer>, "funded_month": "<string>", "funded_day": "<string>", "investments": [ { "company": "<string>", "financial_org": { "name": "<string>", "permalink": "<string>" }, "person": { "first_name": "<string>", "last_name": "<string>", "permalink": "<string>" } }, ... ] }, ... ], ... }
样本查询
以下各节演示了使用 returnScope 选项检索存储在 mongot 上的 embeddedDocuments 类型字段的示例查询。
以下查询使用 range(MongoDB搜索操作符) 在 funding_rounds.raised_amount 字段中查询大于和等于 5000000 且小于和等于 10000000 的金额。它使用 returnScope 选项查询范围设置为 funding_rounds字段。它返回 funding_rounds 对象数组中存储的所有字段,包括使用 returnStoredSource 选项存储的 funding_rounds.investments 对象数组中的字段。它将结果数量限制为仅包含 5 个 funding_rounds 文档。
1 db.companies.aggregate( 2 { 3 "$search": { 4 "range": { 5 "path": "funding_rounds.raised_amount", 6 "gte": 5000000, 7 "lte": 10000000 8 }, 9 "returnStoredSource": true, 10 "returnScope": { 11 "path": "funding_rounds" 12 } 13 } 14 }, 15 { 16 "$limit": 5 17 } 18 )
[ { round_code: 'a', raised_amount: 5250000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Frazier Technology Ventures', permalink: 'frazier-technology-ventures' }, person: null }, { financial_org: { name: 'Trinity Ventures', permalink: 'trinity-ventures' }, person: null } ] }, { round_code: 'b', raised_amount: 9500000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Accel Partners', permalink: 'accel-partners' }, person: null }, { financial_org: { name: 'Frazier Technology Ventures', permalink: 'frazier-technology-ventures' }, person: null }, { financial_org: { name: 'Trinity Ventures', permalink: 'trinity-ventures' }, person: null } ] }, { round_code: 'a', raised_amount: 5000000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Charles River Ventures', permalink: 'charles-river-ventures' }, person: null }, { financial_org: { name: 'Union Square Ventures', permalink: 'union-square-ventures' }, person: null }, { financial_org: null, person: { first_name: 'Marc', last_name: 'Andreessen', permalink: 'marc-andreessen' } }, { financial_org: null, person: { first_name: 'Dick', last_name: 'Costolo', permalink: 'dick-costolo' } }, { financial_org: null, person: { first_name: 'Naval', last_name: 'Ravikant', permalink: 'naval-ravikant' } }, { financial_org: null, person: { first_name: 'Ron', last_name: 'Conway', permalink: 'ron-conway' } }, { financial_org: null, person: { first_name: 'Chris', last_name: 'Sacca', permalink: 'chris-sacca' } }, { financial_org: null, person: { first_name: 'Greg', last_name: 'Yaitanes', permalink: 'greg-yaitanes' } }, { financial_org: null, person: { first_name: 'Brian', last_name: 'Pokorny', permalink: 'brian-pokorny' } }, { financial_org: { name: 'SV Angel', permalink: 'sv-angel' }, person: null } ] }, { round_code: 'e', raised_amount: 5166511, raised_currency_code: 'USD', investments: [] }, { round_code: 'b', raised_amount: 9000000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Charles River Ventures', permalink: 'charles-river-ventures' }, person: null }, { financial_org: { name: 'Redpoint Ventures', permalink: 'redpoint-ventures' }, person: null }, { financial_org: { name: 'The Kinsey Hills Group', permalink: 'kinsey-hills-group' }, person: null } ] } ]
以下查询使用 compound 操作符在同一查询中搜索多层嵌套 embeddedDocuments 字段:
必须与 ``funding_rounds.raised_currency_code`` 匹配与
USD应将
funding_rounds.investments.financial_org.name与Trinity Ventures匹配
它会返回 funding_rounds 对象数组内存储的所有字段,包括 funding_rounds.investments 中的字段。它将结果数量限制为 5 funding_rounds 文档。
1 db.companies.aggregate( 2 { 3 "$search": { 4 "compound": { 5 "must": [{ 6 "text": { 7 "path": "funding_rounds.raised_currency_code", 8 "query": "usd" 9 } 10 }], 11 "should": [{ 12 "phrase": { 13 "path": "funding_rounds.investments.financial_org", 14 "query": "Trinity Ventures", 15 } 16 }] 17 }, 18 "returnStoredSource": true, 19 "returnScope": { 20 "path": "funding_rounds" 21 } 22 } 23 }, 24 { 25 "$limit": 5 26 } 27 )
[ { round_code: 'a', raised_amount: 5250000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Frazier Technology Ventures', permalink: 'frazier-technology-ventures' }, person: null }, { financial_org: { name: 'Trinity Ventures', permalink: 'trinity-ventures' }, person: null } ] }, { round_code: 'b', raised_amount: 9500000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Accel Partners', permalink: 'accel-partners' }, person: null }, { financial_org: { name: 'Frazier Technology Ventures', permalink: 'frazier-technology-ventures' }, person: null }, { financial_org: { name: 'Trinity Ventures', permalink: 'trinity-ventures' }, person: null } ] }, { round_code: 'c', raised_amount: 25000000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'DAG Ventures', permalink: 'dag-ventures' }, person: null }, { financial_org: { name: 'Accel Partners', permalink: 'accel-partners' }, person: null }, { financial_org: { name: 'Trinity Ventures', permalink: 'trinity-ventures' }, person: null }, { financial_org: { name: 'Frazier Technology Ventures', permalink: 'frazier-technology-ventures' }, person: null } ] }, { round_code: 'angel', raised_amount: 500000, raised_currency_code: 'USD', investments: [ { financial_org: null, person: { first_name: 'Peter', last_name: 'Thiel', permalink: 'peter-thiel' } }, { financial_org: null, person: { first_name: 'Reid', last_name: 'Hoffman', permalink: 'reid-hoffman' } } ] }, { round_code: 'a', raised_amount: 12700000, raised_currency_code: 'USD', investments: [ { financial_org: { name: 'Accel Partners', permalink: 'accel-partners' }, person: null }, { financial_org: null, person: { first_name: 'Mark', last_name: 'Pincus', permalink: 'mark-pincus' } }, { financial_org: null, person: { first_name: 'Reid', last_name: 'Hoffman', permalink: 'reid-hoffman' } } ] } ]
以下查询使用 range (MongoDB Search 操作符) 查询 funding_rounds.raised_amount 字段中大于或等于 5000000 且小于或等于 10000000 的金额。它使用 returnScope 选项将查询范围设置为 funding_rounds 字段。它使用 searchRootDocumentId 元字段作为分组密钥,将每个母公司下的匹配 funding_rounds 分组在一起,并计算 avgRaisedAmount 字段中每家公司的平均 raised_amount。它按 avgRaisedAmount 降序排序结果,并将结果数限制为 10 家公司。
1 db.companies.aggregate([ 2 { 3 "$search": { 4 "returnStoredSource": true, 5 "returnScope": { 6 "path": "funding_rounds" 7 }, 8 "range": { 9 "path": "funding_rounds.raised_amount", 10 "gte": 5000000, 11 "lte": 10000000 12 } 13 } 14 }, 15 { 16 "$group": { 17 "_id": { "$meta": "searchRootDocumentId" }, 18 "funding_rounds": { 19 "$push": { 20 "round_code": "$round_code", 21 "raised_amount": "$raised_amount", 22 "raised_currency_code": "$raised_currency_code" 23 } 24 }, 25 "avgRaisedAmount": { "$avg": "$raised_amount" } 26 } 27 }, 28 { "$sort": { "avgRaisedAmount": -1 } }, 29 { "$limit": 10 } 30 ])
[ { _id: ObjectId('52cdef7d4bab8bd675298f82'), funding_rounds: [ { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7e4bab8bd67529af80'), funding_rounds: [ { round_code: 'b', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7f4bab8bd67529be3d'), funding_rounds: [ { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7f4bab8bd67529c52d'), funding_rounds: [ { round_code: 'unattributed', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7e4bab8bd67529ab31'), funding_rounds: [ { round_code: 'c', raised_amount: 10000000, raised_currency_code: 'USD' }, { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7e4bab8bd67529aa94'), funding_rounds: [ { round_code: 'b', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7f4bab8bd67529be6f'), funding_rounds: [ { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7c4bab8bd6752985cb'), funding_rounds: [ { round_code: 'd', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7d4bab8bd675299fd1'), funding_rounds: [ { round_code: 'c', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 }, { _id: ObjectId('52cdef7f4bab8bd67529c2c8'), funding_rounds: [ { round_code: 'debt_round', raised_amount: 10000000, raised_currency_code: 'USD' } ], avgRaisedAmount: 10000000 } ]
以下查询使用 range (MongoDB Search Operator) 查询 funding_rounds.raised_amount 字段中大于等于 5000000 且小于等于 10000000 的金额。它使用 returnScope 选项将查询范围设置为 funding_rounds 字段。它按 raised_amount 降序排序匹配的 funding_rounds ,并将结果限制为前 10 轮融资。然后,它使用 searchRootDocumentId 元字段将每轮融资连接回 companies 集合中的母公司,并返回公司的 name 以及融资轮的 round_code、raised_amount 和 raised_currency_code 字段。
1 db.companies.aggregate([ 2 { 3 "$search": { 4 "returnStoredSource": true, 5 "returnScope": { 6 "path": "funding_rounds" 7 }, 8 "range": { 9 "path": "funding_rounds.raised_amount", 10 "gte": 5000000, 11 "lte": 10000000 12 } 13 } 14 }, 15 { "$sort": { "raised_amount": -1 } }, 16 { "$limit": 10 }, 17 { "$addFields": { "root_id": { "$meta": "searchRootDocumentId" } } }, 18 { 19 "$lookup": { 20 "from": "companies", 21 "localField": "root_id", 22 "foreignField": "_id", 23 "as": "company" 24 } 25 }, 26 { "$unwind": "$company" }, 27 { 28 "$project": { 29 "_id": 0, 30 "round_code": 1, 31 "raised_amount": 1, 32 "raised_currency_code": 1, 33 "company.name": 1 34 } 35 } 36 ])
[ { round_code: 'partial', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'WeFi' } }, { round_code: 'b', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'LinkedIn' } }, { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'Lotame' } }, { round_code: 'c', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'OpenX' } }, { round_code: 'b', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'AddThis' } }, { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'Terabitz' } }, { round_code: 'b', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'Six Apart' } }, { round_code: 'a', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'Snocap' } }, { round_code: 'b', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'Wikia' } }, { round_code: 'unattributed', raised_amount: 10000000, raised_currency_code: 'USD', company: { name: 'Mashery' } } ]