在 casbah 的 find() 查询中使用 $in
我正在尝试在 find() 中使用 casbah 的流体查询。
我的数据是这样的：
{ "_id" : ObjectId("4d7b26efc58bf2b18f14d9cd"), "srcID" : [ "/m/05zppz" ], "relation" : [ "/location/location/people_born_here" ], "dstID" : [ "/m/06sfnt9" ] }
{ "_id" : ObjectId("4d7b26efc58bf2b19014d9cd"), "srcID" : [ "/m/05zppz" ], "relation" : [ "/location/location/people_born_here" ], "dstID" : [ "/m/06fqp8" ] }
{ "_id" : ObjectId("4d7b26efc58bf2b19114d9cd"), "srcID" : [ "/m/05zppz" ], "relation" : [ "/location/location/people_born_here" ], "dstID" : [ "/m/06_7xfd" ] }
我写了下面的代码来查询这个：
val srcIDs:List[String] = List("/m/05zppz", "/m/06sfnt9")
val query = "srcID" $in srcIDs
代码段没有编译并报告这个错误：
error: value $in is not a member of java.lang.String
query = ("srcID" $in srcIDs)
casbah文档有$in的上述语法，但它似乎不起作用。 如何使 $in 查询工作？事实上，我无法使用 Casbah 的 DSL 进行任何流畅的查询，并且它们无法给出相同的错误消息。请帮忙！
I'm trying to use casbah's fluid querying in find().
My data is like this:
{ "_id" : ObjectId("4d7b26efc58bf2b18f14d9cd"), "srcID" : [ "/m/05zppz" ], "relation" : [ "/location/location/people_born_here" ], "dstID" : [ "/m/06sfnt9" ] }
{ "_id" : ObjectId("4d7b26efc58bf2b19014d9cd"), "srcID" : [ "/m/05zppz" ], "relation" : [ "/location/location/people_born_here" ], "dstID" : [ "/m/06fqp8" ] }
{ "_id" : ObjectId("4d7b26efc58bf2b19114d9cd"), "srcID" : [ "/m/05zppz" ], "relation" : [ "/location/location/people_born_here" ], "dstID" : [ "/m/06_7xfd" ] }
I wrote the following code to query this:
val srcIDs:List[String] = List("/m/05zppz", "/m/06sfnt9")
val query = "srcID" $in srcIDs
the code segment does not compile and reports this error:
error: value $in is not a member of java.lang.String
query = ("srcID" $in srcIDs)
The casbah documentation has the above syntax for $in, but it doesn't seem to work.
How to make the $in query work? As a matter of fact, I could not get any fluid query with Casbah's DSL to work and they fail giving the same error msg. Please help!
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评论（2）
问题是
$in不是在字符串上定义的方法。 Casbah 很可能定义了从String对象到包含方法$in的类实例的隐式转换。隐式转换需要先导入到作用域中，然后才能使用。您能给我们指出介绍
$in方法的 Casbah 文档吗？我们将在那里找到需要导入的内容。（对于专家来说：
$不应该保留给编译器生成的字段吗？）The problem is that
$inis not a method defined on strings. Most likely Casbah defines an implicit conversion fromStringobjects to instances of a class that contain the method$in. The implicit conversion needs to beimported into scope before it can be used.Could you point us to the Casbah documentation that introduces the
$inmethod? That's where we will find what needs to be imported.(For the experts: isn't
$supposed to be reserved for compiler generated fields?)我修好了！你的回复非常有帮助。我错过了隐式转换所需的导入语句，因此它将其视为字符串。
我添加了
import com.mongodb.casbah.Imports._，它现在就像一个魅力。谢谢你的提示！I fixed it! You reply was very helpful. I had missed the import statement needed for implicit conversion and hence it was treating it as a String.
I included
import com.mongodb.casbah.Imports._and it works like a charm now. Thanks for the hint!