CODEWITHSUNDEEP
javamongodbaggregation-framework
venkat
venkat

Reputation: 69

Aggregation $cond if condition implementation in Java

I nedded to implement 'if condition'in java i don't know how to do that,So give some suggestion to that

db.test.aggregate(
       [
          {
             $project:
               {
                 data: 1,
                 result:
                   {
                     $cond: { if: { $cond: [ "$salary", 250000 ] }, then: 30, else: 20 }
                   }
               }
          }
       ]
    )

Upvotes: 0

Views: 3245

Answers (1)

Neil Lunn
Neil Lunn

Reputation: 151112

Just Documents and Lists

List<Document> pipeline = Arrays.asList(
  new Document("$project",
    new Document("data1", 1)
      .append("result", new Document(
        "$cond", new Document(
          "if", new Document("$eq", Arrays.asList("$salary", 250000) )
        )
        .append("then", 30)
        .append("else", 20) 
      ))
  )
);

Serializes as:

[
  { "$project": {
    "data1": 1,
    "result": {
      "$cond": {
        "if": { "$eq": [ "$salary", 250000 ] },
        "then": 30,
        "else": 20
      }
    }
  }}
]

Or alternately using the "list" form of $cond:

List<Document> pipeline = Arrays.asList(
  new Document("$project",
    new Document("data1", 1)
      .append("result", new Document(
        "$cond", Arrays.asList(
          new Document("$eq", Arrays.asList("$salary", 250000) ),
          30,
          20
        )
      ))
  )
);

Serializes as:

[
  { "$project": {
    "data1": 1,
    "result": {
      "$cond": [
        { "$eq": [ "$salary", 250000 ] },
        30,
        20
      }
    }
  }}
]

Both are valid usages of $cond.

Also noting the error in your question, you might mean $eq or you might mean $gt or other logical operator on the condition. $cond expects it's "if" to return a boolean.

Depending on the driver you might interchange Document with BasicDBObject instead.

Upvotes: 2

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