What is the best way to include a MongoDB match argument when it is received from the frontend, and to exclude it if it is not provided?

Question

What is the best way to include a MongoDB match argument when it is received from the frontend, and to exclude it if it is not provided?

I'm currently working on creating an aggregation in MongoDB using NodeJS. The goal is to add an argument to the MongoDB match function if it exists when the resolver function is called. However, I'm encountering an issue where if no addition is made, no results are returned. On the flip side, if there is an addition, the query doesn't come out as expected. Currently, it looks like this:

phaseMatch = 'phase': { $in: CAT,MOD }

. How can I make it look like

phaseMatch = 'phase': { $in: ['CAT','MOD'] }

? Is there a way to handle this condition solely within the MongoDB aggregation without involving additional JS code?

async WeeklyTable(_, { batchSize, phase }) {
    let res = [];
    let phaseMatch = "";
    if(phase) phaseMatch = "'phase': { $in: " + phase + " }";
    return await collection.aggregate([{ 
        $match: {
            "segment": { 
                $exists: true, 
                $ne: null 
            },
            phaseMatch
        }    
    }];
}

javascript mongodb

Answer 1

Answer №1

If you're looking to dynamically construct a query condition, there are various methods you can use. Here's a simple example:

async WeeklyTable(_, { batchSize, phase }) {
    const res = [];
    const matchCond = {
        "segment": {
            $exists: true,
            $ne: null
        },
    }
    if(phase) {
        matchCond.phase = {$in: phase}
    };
    return await collection.aggregate([{
        $match: matchCond
    }];
}

If you're considering creating the condition as a string, keep in mind that the Mongo driver does not interpret string arguments as query conditions.

EDIT

If you prefer to avoid using javascript for this task, you could try the following approach:

db.collection.aggregate([
  {
    $match: {
      "segment": {
        $exists: true,
        $ne: null
      },
      $expr: {
        "$setIsSubset": [
          [
            "$phase"
          ],
          {
            $ifNull: [
              phase,
              [
                "$phase"
              ]
            ]
          }
        ]
      }
    }
  }
])

Answer 2

If you're looking to dynamically construct a query condition, there are various methods you can use. Here's a simple example:

async WeeklyTable(_, { batchSize, phase }) {
    const res = [];
    const matchCond = {
        "segment": {
            $exists: true,
            $ne: null
        },
    }
    if(phase) {
        matchCond.phase = {$in: phase}
    };
    return await collection.aggregate([{
        $match: matchCond
    }];
}

If you're considering creating the condition as a string, keep in mind that the Mongo driver does not interpret string arguments as query conditions.

EDIT

If you prefer to avoid using javascript for this task, you could try the following approach:

db.collection.aggregate([
  {
    $match: {
      "segment": {
        $exists: true,
        $ne: null
      },
      $expr: {
        "$setIsSubset": [
          [
            "$phase"
          ],
          {
            $ifNull: [
              phase,
              [
                "$phase"
              ]
            ]
          }
        ]
      }
    }
  }
])

What is the best way to include a MongoDB match argument when it is received from the frontend, and to exclude it if it is not provided?

Answer №1

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