如何在Mongoose中按指定分类顺序对Product模型数据排序？

Got it, so you need to sort your Product documents in that specific custom category order: ['Clothes', 'Accessories', 'Footwears']? Regular Mongoose sort() won't cut it here because it only handles alphabetical or numerical ordering. Instead, we'll use MongoDB's aggregation framework to assign a custom priority value to each category, then sort by that value.

Here's the step-by-step solution: #

• First, define your desired custom order array.
• Use the $addFields stage to add a temporary sortPriority field, which uses $indexOfArray to get the position of each document's Category in your custom order.
• Sort the results by this sortPriority field.
• Optional: Remove the temporary sortPriority field with $project if you don't want it in your final results.

Full Code Example: #

const Product = require('./path/to/your/ProductModel');

// Define your desired category order
const customCategoryOrder = ['Clothes', 'Accessories', 'Footwears'];

Product.aggregate([
  // Add a temporary priority field based on custom order
  {
    $addFields: {
      sortPriority: { $indexOfArray: [customCategoryOrder, '$Category'] }
    }
  },
  // Sort by the priority (ascending = your custom order)
  {
    $sort: { sortPriority: 1 }
  },
  // Optional: Remove the temporary sortPriority field from results
  {
    $project: { sortPriority: 0 }
  }
])
.then(sortedProducts => {
  console.log('Products sorted by custom category order:', sortedProducts);
})
.catch(error => {
  console.error('Error sorting products:', error);
});

Handling Categories Outside Your Custom List: #

If you have products with categories not in your customCategoryOrder array, $indexOfArray will return -1, which will make them appear first in the results. If you want those to appear last instead, adjust the sortPriority logic with $cond to assign them a priority higher than your last custom category:

sortPriority: {
  $cond: {
    if: { $in: ['$Category', customCategoryOrder] },
    then: { $indexOfArray: [customCategoryOrder, '$Category'] },
    else: customCategoryOrder.length // Assigns a value higher than all custom indices
  }
}

Bonus: Encapsulate as a Model Static Method #

To make this reusable, add a static method directly to your Mongoose model so you can call it anywhere easily:

// In your Product model file
const mongoose = require('mongoose')
const { Schema } = mongoose
const schema = new Schema({
  Name: { type: String },
  Category: { type: String },
  Price: { type: Number }
})

// Add custom sorting static method
schema.statics.findSortedByCustomCategory = function() {
  const customOrder = ['Clothes', 'Accessories', 'Footwears'];
  return this.aggregate([
    {
      $addFields: {
        sortPriority: {
          $cond: {
            if: { $in: ['$Category', customOrder] },
            then: { $indexOfArray: [customOrder, '$Category'] },
            else: customOrder.length
          }
        }
      }
    },
    { $sort: { sortPriority: 1 } },
    { $project: { sortPriority: 0 } }
  ]);
};

module.exports = mongoose.model('Product', schema);

Now you can call it with just:

Product.findSortedByCustomCategory().then(sortedProducts => {
  // Use your sorted products
});

内容的提问来源于stack exchange，提问作者Petr Vasilev