mongodb - Filter by referenced property in the mongoose -

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• querying after populate in mongoose 5 answers

i'm having hard times trying discovery right way query in mongoose when have relationship.

basically have 1 document objectid relating document (as can see bellow).

but when try filter property of reference, nothing works anymore. basically, problem line ".where({ "recipe.title": new regexp("*") })"

// const configs const config = require('./config');  // mongodb setup const mongoose = require('mongoose'); mongoose.connect(config.database); var schema = mongoose.schema  // recipe schema const recipeschema = mongoose.schema({   title: { type: string },   description: { type: string },   complaints: [{ type: mongoose.schema.types.objectid, ref: 'complaint' }], });  const recipe = mongoose.model('recipe', recipeschema);  // complaint schema const complaintschema = mongoose.schema({   recipe  : { type: mongoose.schema.types.objectid, ref: 'recipe' },   message: { type: string } }); const complaint = mongoose.model('complaint', complaintschema);  /*     after inserting items */  complaint     .find()     .populate("recipe")     .where({ "recipe.title": new regexp("*") }) // not working!     .exec((error, items) => {         items.map((item) => {             console.log(item);         });     }); 

does have correct way solve it?

(1) new regexp("*") not seem valid regular expression because * special , means repeat 0 or more times whatever before in e.g. a* means 0 or more a's.

if trying use *, need escape it: new regexp('\\*')

(2) think you're better off using match (see query conditions , other options).

complaint.find().populate({     path: "recipe"     match: {         title: new regexp('\\*')     } }).exec(...); 

though believe complaints , populate recipes match regular expression.

if want complaints recipes matching regular expression, you're better off doing other way around.

recipe.find({ title: new regexp('\\*') }).populate('complaints').exec(...) 

or using aggregation use $lookup join recipes collection , $match filter documents.

edit: believe like

complaint.aggregate([     // join recipes collection     {         $lookup: {             from: 'recipes',             localfield: 'recipe',             foreignfield: '_id',             as: 'recipe'         }     },     // convert array of recipe object     {         $unwind: '$recipe'     },     // filter     {         $match: {             'recipe.title': new regexp('\\*')         }     } ]).exec(...)