Filtering documents by length of an array of objects-CodePudding

I have the following schema:

const RecipeSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true,
        trim: true
    },
    ingredients: [
        {
            name: {
                type: String,
                required: true,
                trim: true
            },
            amount: {
                type: Number,
                required: true
            }
        }
    ]
});

const Recipe = mongoose.model('Recipe',RecipeSchema);
export {Recipe as default}

I am stuck on filtering the recipes by providing two numbers: min and max, and return the list of recipes that have the number of ingredients ( length of ingredients array ) greater than min and less than max. Can you help me on this one?

CodePudding user response：

here I have used the $expr operator to filter out all those documents which have sizes greater than or equal to min and less than or equal to max.

   let min = 1
   let max  = 2

RecipeModel.find({"$expr":{$gte:[{$size:"$ingredients"},min], $lte:[{$size:"$ingredients"},max]}})

CodePudding user response：

This sequence finally did it

{$where: "this.ingredients.length >= "   min   " && this.ingredients.length <= "   max}