Querying with complex aggregations in MongoDB for sorting operations

Question

Querying with complex aggregations in MongoDB for sorting operations

Can anyone help me with sorting a list of accommodations based on price and number of amenities they offer? The main challenges are converting the price (which is in string format starting with $) to an integer for proper sorting, and determining the count of attributes for each amenity.

This JSON structure provides relevant information about the accommodations. It includes details such as pricing, address, amenities, and reviews for each lodging option.

I attempted to use the MongoDB aggregate function to achieve this, but my limited experience with MongoDB is posing challenges. Here's a snippet of what I tried:

db.lodging.aggregate(
[
{$project: {"substring": {$substr: ["lodging.price", 1,-1 ]}} }, // Convert price from string to substring.
{$project: {intfield: {$toInt: substring}}}, // Convert substring to integer for sorting.
{$project: {}} // TO-DO: Calculate the number of amenities.
{$sort: {intfield: -1, numamenities: -1}}
]
);

javascript mongodb sorting aggregate

Answer 1

Answer №1

Here is an effective aggregation method:

db.lodging.aggregate([
  {
    $addFields: {
      "intfield": {
        $toInt: {
          $substr: ["$lodging.price", 1, -1]
        }
      },
      "numamenities": {
        $size: {
          $objectToArray: "$lodging.amenities"
        }
      }
    }
  },
  {
    $sort: {
      intfield: -1,
      numamenities: -1
    }
  }
])

To start off the process, I used $addFields. Instead of $project, I opted for $addFields because it allows all fields in the document to be passed onto the next stage. If you had used $project with

{$project: {"substring": {$substr: ["lodging.price", 1,-1 ]}} }

, only substring would have been available in the following stage. Hence, $addFields was a better choice.

When dealing with intfield, note that I specified $lodging.price with a $ before lodging. This signifies to MongoDB that the value required is from the field lodging.price and not just the text "lodging.price".

For numamenities, I utilized $objectToArray to transform the lodging.amenities into an array, enabling the use of $size to determine the number of elements.

With intfield and numamenities now included in each document, the final step is to apply $sort.

Answer 2

Here is an effective aggregation method:

db.lodging.aggregate([
  {
    $addFields: {
      "intfield": {
        $toInt: {
          $substr: ["$lodging.price", 1, -1]
        }
      },
      "numamenities": {
        $size: {
          $objectToArray: "$lodging.amenities"
        }
      }
    }
  },
  {
    $sort: {
      intfield: -1,
      numamenities: -1
    }
  }
])

To start off the process, I used $addFields. Instead of $project, I opted for $addFields because it allows all fields in the document to be passed onto the next stage. If you had used $project with

{$project: {"substring": {$substr: ["lodging.price", 1,-1 ]}} }

, only substring would have been available in the following stage. Hence, $addFields was a better choice.

When dealing with intfield, note that I specified $lodging.price with a $ before lodging. This signifies to MongoDB that the value required is from the field lodging.price and not just the text "lodging.price".

For numamenities, I utilized $objectToArray to transform the lodging.amenities into an array, enabling the use of $size to determine the number of elements.

With intfield and numamenities now included in each document, the final step is to apply $sort.

Querying with complex aggregations in MongoDB for sorting operations

Answer №1

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