Shulou(Shulou.com)06/01 Report--

$type operator

Detection type

Category code alias

Double 1 "double"

String 2 "string"

Object 3 "object"

Array 4 "array"

Binary data 5 "binData"

Undefined 6 "undefined" Deprecated.

ObjectId 7 "objectId"

Boolean 8 "bool"

Date 9 "date"

Null 10 "null"

Regular Expression 11 "regex"

DBPointer 12 "dbPointer"

JavaScript 13 "javascript"

Symbol 14 "symbol"

JavaScript (with scope) 15 "javascriptWithScope"

32-bit integer 16 "int"

Timestamp 17 "timestamp"

64-bit integer 18 "long"

Min key-1 "minKey"

Max key 127 "maxKey

Db.article.find ({data: {$type:2}) / / find a document whose data field is string

ForEach function

Use the js function for each document in the query result collection

Cursor.forEach (function) Iterates the cursor to apply a JavaScript function to each document from the cursor.

Use examples

Convert the string in the data.tagList array to int32,x representing the iterated incoming document

Db.article.find ({"data.tagList.0": {$type:2}}) .forEach (function (x) {var iTuno / var length=x.data.tagList.length; for

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