blocks|key|2284726|text|您需要操作符$in来执行此操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2284727|db.prova.find({+"composition.mol_fraction":+{+$in:+[+0,+1+]+}})|code-block|syntax|javascript|2284728|编辑：(按特定顺序搜索)|style|BOLD|2284729|我不知道MongoDB是否像你在对这个答案的评论中所说的那样提供了“过滤优先级”，但是，如果你需要根据数组中按预定顺序出现的值进行过滤，你可以这样做：|2284730|db.prova.find({+
++++"composition.0.mol_fraction":+0,
++++"composition.1.mol_fraction":+1,
})|2284731|这里的缺点是，如果需要查找序列0,1,2+(或更长)，则需要根据值列表的大小动态构建查询。|2284732|同样，这是可行的，但我不知道是否有更复杂的方法来做到这一点。|2284733|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.mongodb.com/manual/reference/operator/query/in/^0|6|3|0|0|0|0|C|0|0|0|F|5|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@$A|13|B|14|1|15]]|C|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|17|8|@$A|18|B|19|K|L]]|9|@]|C|$]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|C|$]]|$1|O|3|P|5|F|7|1B|8|@]|9|@]|C|$G|H]]|$1|Q|3|R|5|6|7|1C|8|@$A|1D|B|1E|K|L]]|9|@]|C|$]]|$1|S|3|T|5|6|7|1F|8|@]|9|@]|C|$]]|$1|U|3|-4|5|6|7|1G|8|@]|9|@]|C|$]]]|V|$W|$5|X|Y|Z|C|$10|11]]]]

You need the operator <a href="https://docs.mongodb.com/manual/reference/operator/query/in/" rel="nofollow noreferrer">$in</a> to do that:

<pre><code>db.prova.find({ "composition.mol_fraction": { $in: [ 0, 1 ] }})
</code></pre>

Edit: (searching by specific order)

I don't know if MongoDB offers a 'filter precedence' like you said in the comment to this answer but, if you need to filter by values that occur in a predetermined sequence in your array you can do:

<pre><code>db.prova.find({ 
 "composition.0.mol_fraction": 0,
 "composition.1.mol_fraction": 1,
})
</code></pre>

The downside here is that, if you need to find the sequence 0,1,2 (or longer), you will need to build your query dynamically, depending on the size of the list of values.

Again, this will work, but I don't know if there are more sophisticated ways to do it.

blocks|key|2497487|text|设计此查询的方法应该是可以动态传递组合数组。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2497488|假设我们在DB中有以下数据：|2497489|{
++++"_id"+:+ObjectId("5d4b2039cbfa696dcd9924a5"),
++++"T_K"+:+750,
++++"P_Pa"+:+2026500,
++++"phi"+:+1,
++++"composition"+:+[
++++++++{
++++++++++++"species"+:+"NC10H22",
++++++++++++"mol_fraction"+:+0
++++++++},
++++++++{
++++++++++++"species"+:+"NC12H26",
++++++++++++"mol_fraction"+:+1
++++++++}
++++]
}
{
++++"_id"+:+ObjectId("5d4b20eecbfa696dcd9924a6"),
++++"T_K"+:+712,
++++"P_Pa"+:+2026501,
++++"phi"+:+2,
++++"composition"+:+[
++++++++{
++++++++++++"species"+:+"H2",
++++++++++++"mol_fraction"+:+0
++++++++},
++++++++{
++++++++++++"species"+:+"O",
++++++++++++"mol_fraction"+:+1
++++++++}
++++]
}
{
++++"_id"+:+ObjectId("5d4b20eecbfa696dcd9924a7"),
++++"T_K"+:+713,
++++"P_Pa"+:+2026502,
++++"phi"+:+2,
++++"composition"+:+[
++++++++{
++++++++++++"species"+:+"Na",
++++++++++++"mol_fraction"+:+2
++++++++},
++++++++{
++++++++++++"species"+:+"H",
++++++++++++"mol_fraction"+:+1
++++++++},
++++++++{
++++++++++++"species"+:+"CO3",
++++++++++++"mol_fraction"+:+4
++++++++}
++++]
}|code-block|syntax|javascript|2497490|现在，我们需要搜索：2,1,4|offset|length|style|BOLD|2497491|下面的查询可以得到预期的结果：|2497492|db.prova.aggregate([
++++{
++++++++$match:{
++++++++++++$expr:{
++++++++++++++++$eq:[
++++++++++++++++++++[2,1,4],
++++++++++++++++++++{
++++++++++++++++++++++++$map:{
++++++++++++++++++++++++++++input:"$composition",
++++++++++++++++++++++++++++as:"composition",
++++++++++++++++++++++++++++in:{
++++++++++++++++++++++++++++++++$trunc:+"$$composition.mol_fraction"
++++++++++++++++++++++++++++}
++++++++++++++++++++++++}
++++++++++++++++++++}
++++++++++++++++]
++++++++++++}
++++++++}
++++}
]).pretty()|2497493|输出：|2497494|{
++++"_id"+:+ObjectId("5d4b20eecbfa696dcd9924a7"),
++++"T_K"+:+713,
++++"P_Pa"+:+2026502,
++++"phi"+:+2,
++++"composition"+:+[
++++++++{
++++++++++++"species"+:+"Na",
++++++++++++"mol_fraction"+:+2
++++++++},
++++++++{
++++++++++++"species"+:+"H",
++++++++++++"mol_fraction"+:+1
++++++++},
++++++++{
++++++++++++"species"+:+"CO3",
++++++++++++"mol_fraction"+:+4
++++++++}
++++]
}|2497495|我们做了什么？|2497496|2497497|匹配该组合以根据准备的组合进行搜索。该组合物是使用$map聚合器从摩尔分数(按相同顺序)制备的。|unordered-list-item|2497498|2497499|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.mongodb.com/manual/reference/operator/aggregation/map/^0|0|0|0|9|6|0|0|0|0|0|0|7|0|0|P|4|0|0|0^^$0|@$1|2|3|4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1C|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1D|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|1E|8|@$K|1F|L|1G|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1H|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|1I|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1J|8|@]|9|@]|A|$]]|$1|U|3|V|5|F|7|1K|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|1L|8|@$K|1M|L|1N|M|N]]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]|$1|Z|3|10|5|11|7|1P|8|@]|9|@$K|1Q|L|1R|1|1S]]|A|$]]|$1|12|3|-4|5|6|7|1T|8|@]|9|@]|A|$]]|$1|13|3|-4|5|6|7|1U|8|@]|9|@]|A|$]]]|14|$15|$5|16|17|18|A|$19|1A]]]]

The way to design this query should be in a way that the array of composition can be passed dynamically. 

Let's say, we have the following data in DB:

<pre><code>{
 "_id" : ObjectId("5d4b2039cbfa696dcd9924a5"),
 "T_K" : 750,
 "P_Pa" : 2026500,
 "phi" : 1,
 "composition" : [
 {
 "species" : "NC10H22",
 "mol_fraction" : 0
 },
 {
 "species" : "NC12H26",
 "mol_fraction" : 1
 }
 ]
}
{
 "_id" : ObjectId("5d4b20eecbfa696dcd9924a6"),
 "T_K" : 712,
 "P_Pa" : 2026501,
 "phi" : 2,
 "composition" : [
 {
 "species" : "H2",
 "mol_fraction" : 0
 },
 {
 "species" : "O",
 "mol_fraction" : 1
 }
 ]
}
{
 "_id" : ObjectId("5d4b20eecbfa696dcd9924a7"),
 "T_K" : 713,
 "P_Pa" : 2026502,
 "phi" : 2,
 "composition" : [
 {
 "species" : "Na",
 "mol_fraction" : 2
 },
 {
 "species" : "H",
 "mol_fraction" : 1
 },
 {
 "species" : "CO3",
 "mol_fraction" : 4
 }
 ]
}
</code></pre>

Now, we need to search for composition: [2,1,4]

The following query can get us the expected result:

<pre><code>db.prova.aggregate([
 {
 $match:{
 $expr:{
 $eq:[
 [2,1,4],
 {
 $map:{
 input:"$composition",
 as:"composition",
 in:{
 $trunc: "$$composition.mol_fraction"
 }
 }
 }
 ]
 }
 }
 }
]).pretty()
</code></pre>

Output:

<pre><code>{
 "_id" : ObjectId("5d4b20eecbfa696dcd9924a7"),
 "T_K" : 713,
 "P_Pa" : 2026502,
 "phi" : 2,
 "composition" : [
 {
 "species" : "Na",
 "mol_fraction" : 2
 },
 {
 "species" : "H",
 "mol_fraction" : 1
 },
 {
 "species" : "CO3",
 "mol_fraction" : 4
 }
 ]
}
</code></pre>

What we did?

<ul>
<li>Matched the composition to search against the prepared composition. The composition is prepared from the mole fractions(in the same sequence) using the <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/map/" rel="nofollow noreferrer">$map</a> aggregator.</li>
</ul>

I have a database with such a structure:

<pre><code>{
 "_id" : ObjectId("x"),
 "T_K" : 750,
 "P_Pa" : 2026500,
 "phi" : 1,
 "composition" : [
 {
 "species" : "NC10H22",
 "mol_fraction" : 0
 },
 {
 "species" : "NC12H26",
 "mol_fraction" : 1
 }
 ],
</code></pre>

And my goal is to find the objects with a certain composition (given by the field "mol_fraction"), let's say [0,1].
But if I try the following command:

<pre><code>db.prova.find({"composition.mol_fraction":[0,1]})
</code></pre>

It doesn't find anything. How can I do that?

Note that if I use instead:

<pre><code>db.prova.find({"composition.mol_fraction":0})
</code></pre>

It finds all the objects with one of the "mol_fraction" field equal to 0.

Query a field in a nested document "as an array"

数据库

MongoDB

我有一个数据库，它具有这样的结构：{    "_id" : ObjectId("x"),    "T_K" : 750,    "P_Pa" : 2026500,    "phi" : 1,    "composition" : [        {            "species" : "NC10H22", ...

问查询嵌套文档中的字段“作为数组”
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