Question

当我尝试重塑我的集合中的日期字段时，我收到错误。

这是架构，我想重塑保存日期的sent字段：

> db.complaints.findOne()
{
    "_id" : ObjectId("55e5990d991312e2c9b266e3"),
    "complaintID" : 1388734,
    "product" : "mortgage",
    "subProduct" : "conventional adjustable mortgage (arm)",
    "issue" : "loan servicing, payments, escrow account",
    "subIssue" : "",
    "state" : "va",
    "ZIP" : 22204,
    "submitted" : "web",
    "received" : "2015-05-22",
    "sent" : "2015-05-22",
    "company" : "green tree servicing, llc",
    "response" : "closed with explanation",
    "timely" : "yes",
    "disputed" : ""
}

这是我收到的查询和错误消息：

db.complaints.aggregate([
{$project:
    {_id:0, 
    sent: 1, 
    Year:{$year:"$sent"},
    Month: {$month:"$sent"}, 
    Day: {$dayOfMonth: "$sent"}, 
    product : 1}},

])
> db.complaints.aggregate([
... {$project:
... {_id:0,
... sent: 1,
... Year:{$year:"$sent"},
... Month: {$month:"$sent"},
... Day: {$dayOfMonth: "$sent"},
... product : 1}},
...
... ])
assert: command failed: {
    "errmsg" : "exception: can't convert from BSON type String to Date",
    "code" : 16006,
    "ok" : 0
} : aggregate failed
Error: command failed: {
    "errmsg" : "exception: can't convert from BSON type String to Date",
    "code" : 16006,
    "ok" : 0
} : aggregate failed
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at Function.assert.commandWorked (src/mongo/shell/assert.js:254:5)
at DBCollection.aggregate (src/mongo/shell/collection.js:1278:12)
at (shell):1:15
2015-09-12T13:16:22.876+0100 E QUERY    Error: command failed: {
    "errmsg" : "exception: can't convert from BSON type String to Date",
    "code" : 16006,
    "ok" : 0
} : aggregate failed
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at Function.assert.commandWorked (src/mongo/shell/assert.js:254:5)
at DBCollection.aggregate (src/mongo/shell/collection.js:1278:12)
at (shell):1:15 at src/mongo/shell/assert.js:13
> db.complaints.aggregate([
... {$project:
... {_id:0,
... sent: 1,
... Year:{$year:"$sent"},
... Month: {$month:"$sent"},
... Day: {$dayOfMonth: "$sent"},
... product : 1}},
...
... ])
assert: command failed: {
    "errmsg" : "exception: can't convert from BSON type String to Date",
    "code" : 16006,
    "ok" : 0
} : aggregate failed
Error: command failed: {
    "errmsg" : "exception: can't convert from BSON type String to Date",
    "code" : 16006,
    "ok" : 0
} : aggregate failed
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at Function.assert.commandWorked (src/mongo/shell/assert.js:254:5)
at DBCollection.aggregate (src/mongo/shell/collection.js:1278:12)
at (shell):1:15
2015-09-12T13:21:08.767+0100 E QUERY    Error: command failed: {
    "errmsg" : "exception: can't convert from BSON type String to Date",
    "code" : 16006,
    "ok" : 0
} : aggregate failed
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at Function.assert.commandWorked (src/mongo/shell/assert.js:254:5)
at DBCollection.aggregate (src/mongo/shell/collection.js:1278:12)
at (shell):1:15 at src/mongo/shell/assert.js:13
>

Answer 1

您只能将$year之类的日期运算符用于具有BSON日期数据类型的值。您的sent字段的值是一个字符串，因此您需要使用$substr来按位置拆分日期字符串：

db.complaints.aggregate([
{$project:
    {_id: 0, 
    sent: 1, 
    Year: {$substr: ["$sent", 0, 4]},
    Month: {$substr: ["$sent", 5, 2]}, 
    Day: {$substr: ["$sent", 8, 2]}, 
    product: 1}}
])

结果：

{
"product" : "mortgage",
"sent" : "2015-05-22",
"Year" : "2015",
"Month" : "05",
"Day" : "22"
}

使用MongoDB中的$ project转换日期

1 个答案: