Question

我完全被难过了！

我在名为“Gene”的集合中有以下文档结构，我感兴趣的子文档是“DrugDBI”。我希望返回的字段是“drug_name”而没有别的;这里是“AAA”和“LLL”。

{
 "ADR": [
{
  "adverse_type": "YYY",
}
],
"DrugDBI": [
{
  "cancer_type": "XXX",
  "drug_name": "AAAA",
},
{
  "cancer_type": "1405-87-4",
  "drug_name": "LLL",
}
]
"_id": "A2M",
"ts": { "$date": 1395239463625 }
}

和

我需要从子文档中提取一个字段（即“drug_name”），同时通过id查询;

例如;

我的查询ID是@gene_v;这是“A2M”

@gened = DB['Gene'].find({_id:@gene_v,fields:[{"DrugDBI" => {"$elemMatch" => {"$in" => "drug_name" } }}]}).to_a

puts "Drugs related to genes -> <#{@gened}>"

这显然不会返回任何价值。我感谢任何帮助。

当前输出为;

Drugs related to genes -> <[]>

Answer 1

MongoDB只提供＆＃34;文件＆＃34;而不是任意单个字段值，也不是字段值数组。因此，您始终必须按键从文档中提取单个值。但是，MongoDB和文档的主要优势是与编程语言结构相匹配，因此授权您使用您的编程语言。您应该将编程语言视为首选工具。

MongoDB查找查询仅允许简单地投影/选择顶级字段。您可以使用聚合框架进行更复杂的提取和转换，但我建议你先用你的编程语言。我希望以下测试能够为您说明所有这些。

test.rb

require 'mongo'
require 'json'
require 'test/unit'

class MyTest < Test::Unit::TestCase
  def setup
    @coll = Mongo::MongoClient.new['test']['Gene']
    doc = JSON.parse <<-EOT
    { "ADR" : [{"adverse_type" : "YYY"}],
      "DrugDBI" : [{"cancer_type" : "XXX", "drug_name" : "AAAA"}, {"cancer_type" : "1405-87-4", "drug_name" : "LLL"}],
      "_id" : "A2M",
      "ts" : {"$date" : 1395239463625}
    }
    EOT
    @coll.remove
    @coll.insert(doc)
  end

  test "extract cancer drugs" do
    @gene_v = "A2M"

    doc = @coll.find({_id:@gene_v},fields:["DrugDBI"]).to_a.first
    @gened = doc["DrugDBI"].collect{|cancer_drug| cancer_drug["drug_name"]}
    assert_equal(["AAAA", "LLL"], @gened)
    puts "Drugs related to genes -> <#{@gened}>"

    doc = @coll.aggregate([
      {"$match" => {"_id" => @gene_v}},
      {"$unwind" => "$DrugDBI"},
      {"$project" => {"drug_name" => "$DrugDBI.drug_name"}},
      {"$group" => {"_id" => "$_id", "drug_name" => {"$push" => "$drug_name"}}}
    ]).to_a.first
    @gened = doc["drug_name"]
    assert_equal(["AAAA", "LLL"], @gened)
    puts "Drugs related to genes -> <#{@gened}>"
  end
end

$ ruby test.rb

Loaded suite test
Started
Drugs related to genes -> <["AAAA", "LLL"]>
Drugs related to genes -> <["AAAA", "LLL"]>
.

Finished in 0.010455 seconds.

1 tests, 2 assertions, 0 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications

查询嵌套文件mongodb ruby

1 个答案: