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$regexMatch (aggregation)

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Definition定义

$regexMatch

New in version 4.2. 4.2版新增。

Performs a regular expression (regex) pattern matching and returns:执行正则表达式（regex）模式匹配并返回：

  • true if a match exists.如果存在匹配，则为true。
  • false if a match doesn't exist.如果不存在匹配项，则为false。

Prior to MongoDB 4.2, aggregation pipeline can only use the query operator $regex in the $match stage. 在MongoDB 4.2之前，聚合管道只能在$match阶段使用查询运算符$regex。For more information on using regex in a query, see $regex.有关在查询中使用regex的更多信息，请参阅$regex。

Syntax语法

The $regexMatch operator has the following syntax:$regexMatch运算符具有以下语法：

{ $regexMatch: { input: <expression> , regex: <expression>, options: <expression> } }
Field字段Description描述
inputThe string on which you wish to apply the regex pattern. 要应用正则表达式模式的字符串。Can be a string or any valid expression that resolves to a string. 可以是字符串，也可以是解析为字符串的任何有效表达式。
regexThe regex pattern to apply. 要应用的正则表达式模式。Can be any valid expression that resolves to either a string or regex pattern /<pattern>/. 可以是解析为字符串或正则表达式模式/<pattern>/的任何有效表达式。When using the regex /<pattern>/, you can also specify the regex options i and m (but not the s or x options): 使用模式/<pattern>/时，还可以指定正则表达式选项i和m（但不能指定s或x选项）：
  • "pattern"
  • /<pattern>/
  • /<pattern>/<options>
Alternatively, you can also specify the regex options with the options field. 或者，您也可以使用options字段指定regex选项。To specify the s or x options, you must use the options field.若要指定s或x选项，必须使用options字段。
You cannot specify options in both the regex and the options field. 不能在regex和options字段中都指定选项。
optionsOptional. 可选的。The following <options> are available for use with regular expression. 以下<options>可用于正则表达式。
Note
You cannot specify options in both the regex and the options field. 不能在regex和options字段中都指定选项。
Option选项Description描述
iCase insensitivity to match both upper and lower cases. 区分大小写以匹配大小写。You can specify the option in the options field or as part of the regex field.您可以在options字段中指定该选项，也可以将其作为regex字段的一部分。
mFor patterns that include anchors (i.e. ^ for the start, $ for the end), match at the beginning or end of each line for strings with multiline values. 对于包含锚点的模式（例如，^表示开始，$表示结束），对于具有多行值的字符串，请在每行的开头或末尾进行匹配。Without this option, these anchors match at beginning or end of the string.如果没有此选项，这些锚点将在字符串的开头或末尾匹配。
If the pattern contains no anchors or if the string value has no newline characters (e.g. \n), the m option has no effect. 如果模式不包含锚，或者字符串值没有换行符（例如\n），则m选项无效。
x"Extended" capability to ignore all white space characters in the pattern unless escaped or included in a character class.“扩展”功能可以忽略模式中的所有空白字符，除非转义或包含在字符类中。
Additionally, it ignores characters in-between and including an un-escaped hash/pound (#) character and the next new line, so that you may include comments in complicated patterns. 此外，它会忽略介于之间的字符，并包括一个未转义的hash/pund（#）字符和下一个新行，这样您就可以以复杂的模式包含注释。This only applies to data characters; white space characters may never appear within special character sequences in a pattern.这仅适用于数据字符；空白字符可能永远不会出现在模式中的特殊字符序列中。
The x option does not affect the handling of the VT character (i.e. code 11).x选项不影响VT字符（即代码11）的处理。
You can specify the option only in the options field. 只能在options字段中指定选项。
sAllows the dot character (i.e. .) to match all characters including newline characters.允许点字符（即.）与包括换行符在内的所有字符匹配。
You can specify the option only in the options field.只能在options字段中指定选项。

Returns返回值

The operator returns a boolean:运算符返回布尔值：

  • true if a match exists.如果存在匹配，则为true。
  • false if a match doesn't exist.如果不存在匹配项，则为false。
Tip

See also: 另请参阅：

Behavior行为

PCRE LibraryPCRE库

Starting in version 6.1, MongoDB uses the PCRE2 (Perl Compatible Regular Expressions) library to implement regular expression pattern matching. 从6.1版本开始，MongoDB使用PCRE2(PerlCompatibleRegularExpressions)库来实现正则表达式模式匹配。To learn more about PCRE2, see the PCRE Documentation.要了解有关PCRE2的更多信息，请参阅PCRE文档。

$regexMatch and Collation和排序规则

$regexMatch ignores the collation specified for the collection, db.collection.aggregate(), and the index, if used.忽略为集合、db.collection.aggregate()和索引（如果用了的话）指定的排序规则。

For example, the create a sample collection with collation strength 1 (i.e. compare base character only and ignore other differences such as case and diacritics):例如，创建排序规则强度为1的示例集合（即，仅比较基本字符，忽略其他差异，如大小写和变音符号）：

db.createCollection( "myColl", { collation: { locale: "fr", strength: 1 } } )

Insert the following documents:插入以下文件：

db.myColl.insertMany([
   { _id: 1, category: "café" },
   { _id: 2, category: "cafe" },
   { _id: 3, category: "cafE" }
])

Using the collection's collation, the following operation performs a case-insensitive and diacritic-insensitive match:使用集合的排序规则，以下操作执行不区分大小写和不区分重音符号的匹配：

db.myColl.aggregate( [ { $match: { category: "cafe" } } ] )

The operation returns the following 3 documents:该操作返回以下3个文档：

{ "_id" : 1, "category" : "café" }
{ "_id" : 2, "category" : "cafe" }
{ "_id" : 3, "category" : "cafE" }

However, the aggregation expression $regexMatch ignores collation; that is, the following regular expression pattern matching examples are case-sensitive and diacritic sensitive:但是，聚合表达式$regexMatch忽略排序规则；也就是说，以下正则表达式模式匹配示例区分大小写和变音符号：

db.myColl.aggregate( [ { $addFields: { results: { $regexMatch: { input: "$category", regex: /cafe/ }  } } } ] )
db.myColl.aggregate(
   [ { $addFields: { results: { $regexMatch: { input: "$category", regex: /cafe/ }  } } } ],
   { collation: { locale: "fr", strength: 1 } }       // Ignored in the $regexMatch
)

Both operations return the following:两个操作都返回以下内容：

{ "_id" : 1, "category" : "café", "results" : false }
{ "_id" : 2, "category" : "cafe", "results" : true }
{ "_id" : 3, "category" : "cafE", "results" : false }

To perform a case-insensitive regex pattern matching, use the i Option instead. 要执行不区分大小写的regex模式匹配，请改用i选项。See i Option for an example.有关示例，请参阅i选项。

Examples实例

$regexMatch and Its Options及其选项

To illustrate the behavior of the $regexMatch operator as discussed in this example, create a sample collection products with the following documents:为了说明本例中讨论的$regexMatch运算符的行为，请使用以下文档创建一个示例集合products：

db.products.insertMany([
   { _id: 1, description: "Single LINE description." },
   { _id: 2, description: "First lines\nsecond line" },
   { _id: 3, description: "Many spaces before     line" },
   { _id: 4, description: "Multiple\nline descriptions" },
   { _id: 5, description: "anchors, links and hyperlinks" },
   { _id: 6, description: "métier work vocation" }
])

By default, $regexMatch performs a case-sensitive match. For example, the following aggregation performs a case-sensitive $regexMatch on the description field. The regex pattern /line/ does not specify any grouping:默认情况下，$regexMatch执行区分大小写的匹配。例如，以下聚合对description字段执行区分大小写的$regexMatch。正则表达式模式/line/未指定任何分组：

db.products.aggregate([
   { $addFields: { result: { $regexMatch: { input: "$description", regex: /line/ } } } }
])

The operation returns the following:该操作返回以下内容：

{ "_id" : 1, "description" : "Single LINE description.", "result" : false }
{ "_id" : 2, "description" : "First lines\nsecond line", "result" : true }
{ "_id" : 3, "description" : "Many spaces before     line", "result" : true }
{ "_id" : 4, "description" : "Multiple\nline descriptions", "result" : true }
{ "_id" : 5, "description" : "anchors, links and hyperlinks", "result" : false }
{ "_id" : 6, "description" : "métier work vocation", "result" : false }

The following regex pattern /lin(e|k)/ specifies a grouping (e|k) in the pattern:以下regex模式/lin(e|k)/指定模式中的分组(e|k)：

db.products.aggregate([
   { $addFields: { result: { $regexMatch: { input: "$description", regex: /lin(e|k)/ } } } }
])

The operation returns the following:该操作返回以下内容：

{ "_id" : 1, "description" : "Single LINE description.", "result" : false }
{ "_id" : 2, "description" : "First lines\nsecond line", "result" : true }
{ "_id" : 3, "description" : "Many spaces before     line", "result" : true }
{ "_id" : 4, "description" : "Multiple\nline descriptions", "result" : true }
{ "_id" : 5, "description" : "anchors, links and hyperlinks", "result" : true }
{ "_id" : 6, "description" : "métier work vocation", "result" : false }

i Option选项

Note

You cannot specify options in both the regex and the options field.不能在regex和options字段中都指定选项。

To perform case-insensitive pattern matching, include the i option as part of the regex field or in the options field:要执行不区分大小写的模式匹配，请将i选项作为regex字段或options字段的一部分：

// Specify i as part of the regex field
{ $regexMatch: { input: "$description", regex: /line/i } }

// Specify i in the options field
{ $regexMatch: { input: "$description", regex: /line/, options: "i" } }
{ $regexMatch: { input: "$description", regex: "line", options: "i" } }

For example, the following aggregation performs a case-insensitive $regexMatch on the description field. 例如，以下聚合对description字段执行不区分大小写的$regexMatch。The regex pattern /line/ does not specify any grouping:正则表达式模式/line/未指定任何分组：

db.products.aggregate([
   { $addFields: { result: { $regexMatch: { input: "$description", regex: /line/i } } } }
])

The operation returns the following documents:该操作返回以下文档：

{ "_id" : 1, "description" : "Single LINE description.", "result" : true }
{ "_id" : 2, "description" : "First lines\nsecond line", "result" : true }
{ "_id" : 3, "description" : "Many spaces before     line", "result" : true }
{ "_id" : 4, "description" : "Multiple\nline descriptions", "result" : true }
{ "_id" : 5, "description" : "anchors, links and hyperlinks", "result" : false }
{ "_id" : 6, "description" : "métier work vocation", "result" : false }

m Option

Note

You cannot specify options in both the regex and the options field.不能在regex和options字段中都指定选项。

To match the specified anchors (e.g. ^, $) for each line of a multiline string, include the m option as part of the regex field or in the options field:要为多行字符串的每一行匹配指定的锚点（例如^、$），请将m选项作为regex字段或options字段的一部分：

// Specify m as part of the regex field
{ $regexMatch: { input: "$description", regex: /line/m } }

// Specify m in the options field
{ $regexMatch: { input: "$description", regex: /line/, options: "m" } }
{ $regexMatch: { input: "$description", regex: "line", options: "m" } }

The following example includes both the i and the m options to match lines starting with either the letter s or S for multiline strings:以下示例包括i和m选项，用于匹配多行字符串中以字母s或S开头的行：

db.products.aggregate([
   { $addFields: { result: { $regexMatch: { input: "$description", regex: /^s/im } } } }
])

The operation returns the following:该操作返回以下内容：

{ "_id" : 1, "description" : "Single LINE description.", "result" : true }
{ "_id" : 2, "description" : "First lines\nsecond line", "result" : true }
{ "_id" : 3, "description" : "Many spaces before     line", "result" : false }
{ "_id" : 4, "description" : "Multiple\nline descriptions", "result" : false }
{ "_id" : 5, "description" : "anchors, links and hyperlinks", "result" : false }
{ "_id" : 6, "description" : "métier work vocation", "result" : false }

x Option选项

Note

You cannot specify options in both the regex and the options field.不能在regex和options字段中都指定选项。

To ignore all unescaped white space characters and comments (denoted by the un-escaped hash # character and the next new-line character) in the pattern, include the s option in the options field:要忽略模式中所有未转义的空白字符和注释（由未转义的hash#字符和下一个换行符表示），请在options字段中包含s选项：

// Specify x in the options field
{ $regexMatch: { input: "$description", regex: /line/, options: "x" } }
{ $regexMatch: { input: "$description", regex: "line", options: "x" } }

The following example includes the x option to skip unescaped white spaces and comments:以下示例包括用于跳过未跳过的空白和注释的x选项：

db.products.aggregate([
   { $addFields: { returns: { $regexMatch: { input: "$description", regex: /lin(e|k) # matches line or link/, options:"x" } } } }
])

The operation returns the following:该操作返回以下内容：

{ "_id" : 1, "description" : "Single LINE description.", "returns" : false }
{ "_id" : 2, "description" : "First lines\nsecond line", "returns" : true }
{ "_id" : 3, "description" : "Many spaces before     line", "returns" : true }
{ "_id" : 4, "description" : "Multiple\nline descriptions", "returns" : true }
{ "_id" : 5, "description" : "anchors, links and hyperlinks", "returns" : true }
{ "_id" : 6, "description" : "métier work vocation", "returns" : false }

s Option

Note

You cannot specify options in both the regex and the options field.不能在regex和options字段中都指定选项。

To allow the dot character (i.e. .) in the pattern to match all characters including the new line character, include the s option in the options field:要允许模式中的点字符（即.）与包括换行符在内的所有字符匹配，请在options字段中包含s选项：

// Specify s in the options field
{ $regexMatch: { input: "$description", regex: /m.*line/, options: "s" } }
{ $regexMatch: { input: "$description", regex: "m.*line", options: "s" } }

The following example includes the s option to allow the dot character (i.e. .) to match all characters including new line as well as the i option to perform a case-insensitive match:以下示例包括允许点字符（即.）匹配包括新行在内的所有字符的s选项，以及执行不区分大小写匹配的i选项：

db.products.aggregate([
   { $addFields: { returns: { $regexMatch: { input: "$description", regex:/m.*line/, options: "si"  } } } }
])

The operation returns the following:该操作返回以下内容：

{ "_id" : 1, "description" : "Single LINE description.", "returns" : false }
{ "_id" : 2, "description" : "First lines\nsecond line", "returns" : false }
{ "_id" : 3, "description" : "Many spaces before     line", "returns" : true }
{ "_id" : 4, "description" : "Multiple\nline descriptions", "returns" : true }
{ "_id" : 5, "description" : "anchors, links and hyperlinks", "returns" : false }
{ "_id" : 6, "description" : "métier work vocation", "returns" : false }

Use $regexMatch to Check Email Address使用$regexMatch检查电子邮件地址

Create a sample collection feedback with the following documents:使用以下文档创建示例集合feedback：

db.feedback.insertMany([
   { "_id" : 1, comment: "Hi, I'm just reading about MongoDB -- aunt.arc.tica@example.com"  },
   { "_id" : 2, comment: "I wanted to concatenate a string" },
   { "_id" : 3, comment: "How do I convert a date to string? Contact me at either cam@mongodb.com or c.dia@mongodb.com" },
   { "_id" : 4, comment: "It's just me. I'm testing.  fred@MongoDB.com" }
])

The following aggregation uses the $regexMatch to check if the comment field contains an email address with @mongodb.com and categorize the feedback as Employee or External.以下聚合使用$regexMatch检查comment字段是否包含@mongodb.com的电子邮件地址，并将反馈分类为Employee或External。

db.feedback.aggregate( [
    { $addFields: {
       "category": { $cond: { if:  { $regexMatch: { input: "$comment", regex: /[a-z0-9_.+-]+@mongodb.com/i } },
                              then: "Employee",
                              else: "External" } }
    } },

The operation returns the following documents:该操作返回以下文档：

{ "_id" : 1, "comment" : "Hi, I'm just reading about MongoDB -- aunt.arc.tica@example.com", "category" : "External" }
{ "_id" : 2, "comment" : "I wanted to concatenate a string", "category" : "External" }
{ "_id" : 3, "comment" : "How do I convert a date to string? Contact me at either cam@mongodb.com or c.dia@mongodb.com", "category" : "Employee" }
{ "_id" : 4, "comment" : "It's just me. I'm testing.  fred@MongoDB.com", "category" : "Employee" }