$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，请将短语用转义双引号（\"）括起来，如：

"\"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，则文本搜索将只匹配包含该短语的文档。

For example, passed a $search string:例如，传递了一个$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（-）会否定单词：

• The negated word excludes documents that contain the negated word from the result set.否定词将包含否定词的文档从结果集中排除。
• When passed a search string that only contains negated words, text search will not match any documents.当传递一个只包含否定单词的搜索字符串时，文本搜索将不匹配任何文档。
• A hyphenated word, such as pre-market, is not a negation. If used in a hyphenated word, $text operator treats the hyphen-minus (-) as a delimiter. 连字符的单词，例如pre-market，不是否定词。如果在连字符单词中使用，$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market这个词，需要在pre和-market之间留出一个空间，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运算符将所有否定项添加到查询中。

Stop Words停止文字

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

Stemmed Words词干单词

For case insensitive and diacritic insensitive text searches, the $text operator matches on the complete stemmed word. 对于不区分大小写和不区分重音符号的文本搜索，$text运算符会在完整词干上匹配。So if a document field contains the word blueberry, a search on the term blue will not match. 因此，如果文档字段包含单词blueberry，则对单词蓝色的搜索将不匹配。However, blueberry or blueberries will match.然而，blueberry或blueberries会匹配。

$caseSensitive Option选项

To support case sensitive search where the text index is case insensitive, specify $caseSensitive: true.若要支持text索引不区分大小写的区分大小写搜索，请指定$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变音符号的匹配项。
• 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查询操作包括一个额外的阶段，用于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，$text运算符将与确切的单词匹配。

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 text index, specify $diacriticSensitive: true.若要支持对text索引进行区分重音符号的文本搜索，请指定$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符号的，不能不区分重音符号。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 ProcessDiacritic敏感搜索过程

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

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

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 $text operator searches the text index, which is diacritic sensitive.若要对早期版本的text索引执行区分重音符号的搜索，$text运算符将搜索区分重音字符的文本索引。

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

Case Sensitive Search for a Term区分大小写搜索术语

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:搜索仅匹配文档：

{ "_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:搜索仅匹配文档：

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

Case Sensitivity with Negated Term带负项的区分大小写

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 $text operator will exclude the documents that contain those terms from the results. 如果否定术语，$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.您还可以为否定项指定区分大小写。

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但不包含小写单词shop的文档执行区分大小写的搜索，或者更准确地说，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术语的变音敏感搜索

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变音敏感文本搜索：

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具有否定项的偏转词敏感性

The $diacriticSensitive option applies also to negated terms. $diacriticSensitive选项也适用于否定项。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 $text operator will exclude the documents that contain those terms from the results.如果否定术语，$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:以下查询对包含单词leches但不包含单词cafés的文档执行区分重音符号的文本搜索，或者更准确地说，搜索单词的词干版本：

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 $meta operator in the projection document to append the relevance score to each matching document:以下查询对术语cake执行文本搜索，并使用投影文档中的$meta运算符将相关性分数附加到每个匹配文档：

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，则投影和排序文档可以为该表达式使用不同的字段名。
  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，在下面的操作中，投影使用名为score的字段作为表达式，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, to sort by the text score, include the same $meta expression in both the projection document and the sort expression. The following query searches for the term coffee and sorts the results by the descending score:在MongoDB 4.2中，要根据文本得分进行排序，请在投影文档和排序表达式中都包含相同的$meta表达式。以下查询搜索术语coffee，并按降序对结果进行排序：

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

  The query returns the matching documents sorted by descending score.查询返回按降序排列的匹配文档。

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.将limit()方法与sort()结合使用可以返回前n个匹配的文档。

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:以下查询搜索术语coffee，并按降序对结果进行排序，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带有附加查询和排序表达式的文本搜索

The following query searches for documents where the author equals "xyz" and the indexed field subject contains the terms coffee or bake. 以下查询搜索author等于"xyz"并且索引字段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:该操作还指定了按date升序，然后按文本搜索分数降序排列的排序顺序：

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