指定要在VoyageMongo中返回的字段

时间:2017-05-05 09:42:18

标签: mongodb pharo

我正在寻找限制VoyageMongo查询的返回字段的可能性。 假设我有db.persons字段(personId,firstName,lastName)。 在Mongo我可以通过
查询 db.persons.find( { }, {'personId' : 1} )
在VoyageMongo中,似乎发送到JSON查询的所有字典条目都被整理成$和查询。 MongoQuery中的字段有一个instVar和Accessors,但我不知道如何设置它们。 有没有办法在VoyageMongo中指定返回字段?

此致

最高

1 个答案:

答案 0 :(得分:0)

在搜索了一段时间后,我找到的唯一选项是扩展Class,VOMongoRepository,VOMongoRepositoryResolver和MongoCollection。 我添加了一个带有
的消息链 Class>>selectMany: aBlock options: someOptions ^self voyageRepository selectMany: self where: aBlock options: someOptions VOMongoRepository>>selectMany: aClass where: aDictionary options: someOptions | selected | selected := resolver selectMany: aClass where: aDictionary options: someOptions. ^aClass = aClass persistentClass ifTrue: [ selected ] ifFalse: [ selected select: [ :each | each isKindOf: aClass ] ] VOMongoRepositoryResolver>>selectMany: aClass where: aDictionary options: someOptions self execute: [ ^self basicSelectMany: aClass where: aDictionary options: someOptions ] VOMongoRepositoryResolver>>basicSelectMany: aClass where: aDictionary options: someOptions "Selecting instances of aClass should be done in the mongo query, not here" self flag: #todo. ^((self basicRawSelectMany: aClass where: aDictionary options: someOptions) collect: [ :each | self retrieveObjectOf: aClass json: each ] as: repository collectionClass) select: [ :each | each isKindOf: aClass ] VOMongoRepositoryResolver>>basicRawSelectMany: aClass where: aDictionary options: someOptions ^self pool withDatabase: [ :db | (self collectionAt: aClass inDatabase: db) select: aDictionary options: someOptions ] MongoCollection>>select: aDictionary options: someOptions ^ self query: [:query | query where: aDictionary; limit: (someOptions at: 'limit' ifAbsent: nil); offset: (someOptions at: 'offset' ifAbsent: nil); fields: (someOptions at: 'fields' ifAbsent: nil) ]

这解决了这个问题。 消息以这种方式发送:

options := { 'fields' -> { 'personId' -> 1 } asDictionary } asDictionary.
^ self selectMany: [ :each |
    (each at: 'name') = 'Max' ]
    options: options

还可以在options目录中添加限制和偏移量。 由于我有许多字段的对象,因此仅获取其中几个字段时的性能已从48000毫秒变为229毫秒 我创建了一个包含扩展名的包。