How to $match a field conditionally in mongo DB-CodePudding

I have the following schema:

User: {
...otherFields,
isDumb: false,
type: "A" // could be "A", "B", or "C"
}

I want to fetch all dumb users by default and fetch by type only if the type is passed through the parameters.

    static async getUsers(req: any, res: Response) {
        const { type = "" } = req.params;
        const queryPipeline = [
            {
                $match: {
                    isDumb: true,
                    type: // I want to only filter by type if the param is passed in
                }
            }
         ]
         const users = await User.aggregate(queryPipeline);

So if my data was:

[
  {
    ...otherFields,
    isDumb: false,
    type: "A"
  },
  {
    ...otherFields,
    isDumb: true,
    type: "B"
  },
  {
    ...otherFields,
    isDumb: true,
    type: "C"
  }
]

and req.params.type was "B", I should get back:

[
  {
    ...otherFields,
    isDumb: true,
    type: "B"
  }
],

if req.params.type was undefined, I should get all dumb users

[
  {
    ...otherFields,
    isDumb: true,
    type: "B"
  },
  {
    ...otherFields,
    isDumb: true,
    type: "C"
  }
]

CodePudding user response：

you just have to build an object and pass it to match

const matchParams = req.params.type ? {isDumb:true,type:req.params.type } : {isDumb:true }

CodePudding user response：

You can create the object using JS:

const params = "A" // get req.params as you want
let query = {$match:{isDumb:true}}
if(params) query.$match.type = params

console.log(query)

CodePudding user response：

First, you don't need to use Aggregation Framework for simple find query. You can use find method instead.

Second, consider approach where you initialize the filter with isDumb: true, and add new type property only if req.params.type exists.

let filter = { isDumb: true };
if(req.params.type) filter.type = req.params.type;

const users = await User.find(filter);