$text¶

Phrases短语¶

To match on a phrase, as opposed to individual terms, enclose the phrase in escaped double quotes (\"), as in:要匹配短语，而不是单个术语，请将短语括在转义双引号（\"）中，如下所示：

"\"ssl certificate\""

If the $search string includes a phrase and individual terms, text search will only match the documents that include the phrase.如果$search字符串包含短语和单个术语，则文本搜索将仅匹配包含该短语的文档。

For example, passed a $search string:例如，传递了$search字符串：

"\"ssl certificate\" authority key"

The $text operator searches for the phrase "ssl certificate".$text运算符搜索短语"ssl certificate"。

Negations否定¶

Prefixing a word with a hyphen-minus (-) negates a word:在单词前面加上连字符减号（-）将否定单词：

• The negated word excludes documents that contain the negated word from the result set.否定词从结果集中排除包含否定词的文档。
• When passed a search string that only contains negated words, text search will not match any documents.当传递的搜索字符串仅包含否定词时，文本搜索将不匹配任何文档。
• A hyphenated word, such as pre-market, is not a negation. 带连字符的单词（如pre-market）不是否定词。If used in a hyphenated word, $text operator treats the hyphen-minus (-) as a delimiter. 如果在带连字符的单词中使用，$text运算符将连字符减号（-）视为分隔符。To negate the word market in this instance, include a space between pre and -market, i.e., pre -market.在这种情况下，要否定单词market，请在pre和-market之间加一个空格，即pre -market。

The $text operator adds all negations to the query with the logical AND operator.$text运算符使用逻辑AND运算符将所有否定添加到查询中。

Stop Words停止文字¶

The $text operator ignores language-specific stop words, such as the and and in English.$text运算符忽略特定语言的停止词，例如英语中的the和and。

Stemmed Words词干词¶

For case insensitive and diacritic insensitive text searches, the $text operator matches on the complete stemmed word. 对于不区分大小写和不区分重音的文本搜索，$text运算符匹配完整的词干单词。So if a document field contains the word blueberry, a search on the term blue will not match. 因此，如果文档字段包含blueberry一词，则对blue一词的搜索将不匹配。However, blueberry or blueberries will match.然而，blueberry或blueberrys会相配。

$caseSensitive Option选项¶

To support case sensitive search where the text index is case insensitive, specify $caseSensitive: true.若要在text索引不区分大小写的情况下支持区分大小写的搜索，请指定$caseSensitive:true。

Case Sensitive Search Process区分大小写的搜索过程¶

When performing a case sensitive search ($caseSensitive: true) where the text index is case insensitive, the $text operator:在text索引不区分大小写的情况下执行区分大小写的搜索（$caseSensitive: true）时，$text运算符：

• First searches the text index for case insensitive and diacritic matches.首先在text索引中搜索不区分大小写和区分重音的匹配项。
• Then, to return just the documents that match the case of the search terms, the $text query operation includes an additional stage to filter out the documents that do not match the specified case.然后，为了只返回与搜索词大小写匹配的文档，$text查询操作还包括一个额外的阶段，以筛选出与指定大小写不匹配的文档。

For case sensitive search (i.e. $caseSensitive: true), if the suffix stem contains uppercase letters, the $text operator matches on the exact word.对于区分大小写的搜索（即$caseSensitive: true），如果后缀词干包含大写字母，则$text运算符将匹配确切的单词。

Specifying $caseSensitive: true may impact performance.指定$caseSensitive: true可能会影响性能。

$diacriticSensitive Option选项¶

To support diacritic sensitive text search against the version 3 text index, specify $diacriticSensitive: true.要支持对版本3文本索引进行区分重音的text搜索，请指定$diacriticSensitive:true。

Text searches against earlier versions of the text index are inherently diacritic sensitive and cannot be diacritic insensitive. 针对早期版本的text索引的文本搜索本质上是区分重音的，不能不区分重音。As such, the $diacriticSensitive option for the $text operator has no effect with earlier versions of the text index.因此，$text运算符的$diacriticSensitive选项对早期版本的text索引没有影响。

Diacritic Sensitive Search Process变音敏感搜索过程¶

To perform a diacritic sensitive text search ($diacriticSensitive: true) against a version 3 text index, the $text operator:要对版本3文本索引执行区分重音的text搜索（$diacriticSensitive : true），请使用$text运算符：

• First searches the text index, which is diacritic insensitive.首先搜索不区分重音的text索引。
• Then, to return just the documents that match the diacritic marked characters of the search terms, the $text query operation includes an additional stage to filter out the documents that do not match.然后，为了只返回与搜索词的带变音符号的字符匹配的文档，$text查询操作还包括一个额外的阶段来筛选不匹配的文档。

Specifying $diacriticSensitive: true may impact performance.指定$diacriticSensitive :true可能会影响性能。

To perform a diacritic sensitive search against an earlier version of the text index, the $text operator searches the text index which is diacritic sensitive.要对早期版本的text索引执行区分重音的搜索，$text运算符将搜索区分重音的text索引。

For diacritic sensitive search, if the suffix stem contains the diacritic mark or marks, the $text operator matches on the exact word.对于区分变音符号的搜索，如果后缀词干包含一个或多个变音符号，则$text运算符将匹配确切的单词。

Case Sensitive Search for a Term对术语进行区分大小写的搜索¶

The following query performs a case sensitive search for the term Coffee:以下查询对术语Coffee执行区分大小写的搜索：

db.articles.find( { $text: { $search: "Coffee", $caseSensitive: true } } )

The search matches just the document:搜索仅与文档匹配：

{ "_id" : 2, "subject" : "Coffee Shopping", "author" : "efg", "views" : 5 }

Case Sensitive Search for a Phrase区分大小写搜索短语¶

The following query performs a case sensitive search for the phrase Café Con Leche:以下查询对短语Café Con Leche执行区分大小写的搜索：

db.articles.find( {
   $text: { $search: "\"Café Con Leche\"", $caseSensitive: true }
} )

The search matches just the document:搜索仅与文档匹配：

{ "_id" : 5, "subject" : "Café Con Leche", "author" : "abc", "views" : 200 }

Case Sensitivity with Negated Term带否定项的大小写敏感度¶

A negated term is a term that is prefixed by a minus sign -. 否定项是以减号-为前缀的项。If you negate a term, the $text operator will exclude the documents that contain those terms from the results. 如果对某个术语取反，则$text运算符将从结果中排除包含这些术语的文档。You can also specify case sensitivity for negated terms.还可以为否定项指定大小写敏感度。

The following example performs a case sensitive search for documents that contain the word Coffee but do not contain the lower-case term shop, or more precisely the stemmed version of the words:以下示例对包含单词Coffee但不包含小写术语shop的文档执行区分大小写的搜索，更确切地说，不包含单词的词干版本：

db.articles.find( { $text: { $search: "Coffee -shop", $caseSensitive: true } } )

The query matches the following document:查询与以下文档匹配：

{ "_id" : 2, "subject" : "Coffee Shopping", "author" : "efg" }

Diacritic Sensitive Search for a Term对术语进行区分重音的搜索¶

The following query performs a diacritic sensitive text search on the term CAFÉ, or more precisely the stemmed version of the word:以下查询对术语CAFÉ或更准确地说是单词的词干版本执行区分重音的文本搜索：

db.articles.find( { $text: { $search: "CAFÉ", $diacriticSensitive: true } } )

The query only matches the following document:查询仅与以下文档匹配：

{ "_id" : 5, "subject" : "Café Con Leche", "author" : "abc" }

Diacritic Sensitivity with Negated Term带否定项的变音敏感度¶

The $diacriticSensitive option applies also to negated terms. $diacriticSensitive选项也适用于否定条款。A negated term is a term that is prefixed by a minus sign -. 否定项是以减号-为前缀的项。If you negate a term, the $text operator will exclude the documents that contain those terms from the results.如果对某个术语取反，则$text运算符将从结果中排除包含这些术语的文档。

The following query performs a diacritic sensitive text search for document that contains the term leches but not the term cafés, or more precisely the stemmed version of the words:以下查询对包含术语leches但不包含术语cafés的文档执行区分重音的文本搜索，或者更准确地说，搜索词干版本的文档：

db.articles.find(
  { $text: { $search: "leches -cafés", $diacriticSensitive: true } }
)

The query matches the following document:查询与以下文档匹配：

{ "_id" : 8, "subject" : "Cafe con Leche", "author" : "xyz" }

Return the Text Search Score返回文本搜索分数¶

The following query performs a text search for the term cake and uses the $meta operator in the projection document to append the relevance score to each matching document:以下查询对术语cake执行文本搜索，并在投影文档中使用$meta运算符将相关性得分附加到每个匹配文档中：

db.articles.find(
   { $text: { $search: "cake" } },
   { score: { $meta: "textScore" } }
)

The returned document includes an additional field score that contains the document’s relevance score:返回的文档包括一个额外的字段score，该分数包含文档的相关性分数：

{ "_id" : 3, "subject" : "Baking a cake", "author" : "abc", "views" : 90, "score" : 0.75 }

Sort by Text Search Score按文本搜索分数排序¶

• Starting in MongoDB 4.4, you can specify the { $meta: "textScore" } expression in the sort() without also specifying the expression in the projection. 从MongoDB 4.4开始，您可以在sort()中指定{ $meta: "textScore" }表达式，而无需在投影中指定表达式。For example,例如

  db.articles.find(
     { $text: { $search: "cake" } }
  ).sort( { score: { $meta: "textScore" } } )

  As a result, you can sort the resulting documents by their search relevance without projecting the textScore.因此，您可以根据搜索相关性对结果文档进行排序，而无需投影textScore。

  In earlier versions, to include { $meta: "textScore" } expression in the sort(), you must also include the same expression in the projection.在早期版本中，要在sort()中包含{ $meta: "textScore" }表达式，还必须在投影中包含相同的表达式。
• Starting in MongoDB 4.4, if you include the { $meta: "textScore" } expression in both the projection and sort(), the projection and sort documents can have different field names for the expression.从MongoDB 4.4开始，如果在projection和sort()中都包含{ $meta: "textScore" }表达式，那么投影文档和排序文档可以有不同的表达式字段名。
  For example, in the following operation, the projection uses a field named score for the expression and the sort() uses the field named ignoredName.例如，在以下操作中，投影使用名为score的字段作为表达式，而sort()使用名为ignoredName的字段。

  db.articles.find(
     { $text: { $search: "cake" } } ,
     { score: { $meta: "textScore" } }
  ).sort( { ignoredName: { $meta: "textScore" } } )

  In previous versions of MongoDB, if { $meta: "textScore" } is included in both the projection and sort, you must specify the same field name for the expression.在MongoDB的早期版本中，如果投影和排序中都包含{ $meta: "textScore" }，则必须为表达式指定相同的字段名。

• In MongoDB 4.2 and earlier, to sort by the text score, include the same $meta expression in both the projection document and the sort expression. 在MongoDB 4.2及更早版本中，为了按文本分数排序，在投影文档和排序表达式中都包含相同的$meta表达式。The following query searches for the term coffee and sorts the results by the descending score:以下查询将搜索coffee一词，并按递减分数对结果进行排序：

  db.articles.find(
     { $text: { $search: "coffee" } },
     { score: { $meta: "textScore" } }
  ).sort( { score: { $meta: "textScore" } } )

  The query returns the matching documents sorted by descending score.查询返回按分数降序排序的匹配文档。

Return Top 2 Matching Documents返回前2个匹配文档¶

Use the limit() method in conjunction with a sort() to return the top n matching documents.结合使用limit()方法和sort()返回前n个匹配文档。

The following query searches for the term coffee and sorts the results by the descending score, limiting the results to the top two matching documents:以下查询将搜索coffee一词，并按递减分数对结果进行排序，将结果限制在前两个匹配的文档中：

db.articles.find(
   { $text: { $search: "coffee" } },
   { score: { $meta: "textScore" } }
).sort( { score: { $meta: "textScore" } } ).limit(2)

Text Search with Additional Query and Sort Expressions使用其他查询和排序表达式进行文本搜索¶

The following query searches for documents where the author equals "xyz" and the indexed field subject contains the terms coffee or bake. 下面的查询搜索author等于"xyz"且索引字段subject包含术语coffee或bake的文档。The operation also specifies a sort order of ascending date, then descending text search score:该操作还指定了date升序、文本搜索分数降序的排序顺序：

db.articles.find(
   { author: "xyz", $text: { $search: "coffee bake" } },
   { score: { $meta: "textScore" } }
).sort( { date: 1, score: { $meta: "textScore" } } )