CODEWITHSUNDEEP
node.jsmongodbmongodb-queryaggregation-framework
Eric Pezzulo
Eric Pezzulo

Reputation: 399

MongoDB aggregation failing because "pipeline stage specification object must contain exactly one field"

I have the following aggregation stage that I'd like to add to my pipeline, but it keeps failing. When I use the MongoDB Compass Aggregation GUI, everything works as it should. I even exported that pipeline from the GUI and am using It the same way In my project but I keep getting this error: MongoServerError: A pipeline stage specification object must contain exactly one field.

I even tried to hard-coded a productId in the $match value (the same way I did in the GUI), but still nothing.

What am I doing wrong here?

Aggregation stage:

const formatIncludedInBomStage = ({ includedInBom }) => {
  const includedInBomStage = {
    $unwind: {
      path: '$finale.bomItems',
    },
    $match: {
      'finale.bomItems.productId': includedInBom,
    },
  }
  return includedInBomStage
}

Upvotes: 0

Views: 709

Answers (2)

Eric Pezzulo
Eric Pezzulo

Reputation: 399

Solution:

const formatIncludedInBomStage = ({ includedInBom }) => {
  const filters = {}
  if (includedInBom) {
    const unwindStage = {
      $unwind: {
        path: '$finale.bomItems',
      },
    }
    const matchStage = {
      $match: {
        'finale.bomItems.productId': includedInBom,
        ...filters,
      },
    }
    const bomStages = [unwindStage, matchStage]
    return bomStages
  } else return []
}

const includedInBomStage = formatIncludedInBomStage({
    includedInBom,
})

const cursor = products.aggregate([stage1,stage2,...includedInBomStage])

Upvotes: 0

Steven Spungin
Steven Spungin

Reputation: 29109

Pipeline stages are an array, you are using multiple object properties instead. unwind should be one stage object in the array, and match another object in the array.

const stages = [
      {
        $unwind: {
          path: '$finale.bomItems',
        },
      {
        $match: {
          'finale.bomItems.productId': includedInBom,
        }
      }
]

Upvotes: 1

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