How to query dynamic fields from mongoDB

Question

I have a mongoDb collection with following data:

{
 "material_name": "david",
 "material_unit": "87",
 "version": "1.0"
}

I am using following query field filter to fetch all material related fields which is working alright.

Query query = new Query();
query.fields().include("material_name");
query.fields().include("material_unit");

I have almost 100+ fields names which start with material. Is it possible to query fields with some kind of regex or any alternative approach?.

E.g.

Query query = new Query();
query.fields().include("material*");

Wernfried Domscheit · Accepted Answer · 2022-11-29 08:21:31Z

2

I think the more efficient way is this one:

db.collection.aggregate([
   { $set: { data: { $objectToArray: "$$ROOT" } } },
   {
      $set: {
         data: {
            $filter: {
               input: "$data",
               cond: { $regexMatch: { input: "$$this.k", regex: "^material" } }
            }
         }
      }
   },
   { $replaceWith: { $arrayToObject: "$data" } }
])

You can also filter one the values like cond: { $eq: [ "$$this.v", "david" ] }

answered Nov 29, 2022 at 8:21

Wernfried Domscheit

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