mongo db text search with mongoose

You have to add the plugin to the schema before registering the schema as a model.

UPDATED

Likewise, you need to define the index on the schema before registering the model. So re-order that section of your code like this:

var textSearch = require("mongoose-text-search");
Items.plugin(textSearch);
Items.index({
    type            :"text",
    color           :"text",
    category_A      :"text",
    category_B      :"text",
    category_C      :"text"
}, {
    name: "best_match_index",
    weights: {
        type: 5,  
        color: 4
    }
});
var ItemModel = mongoose.model('Item', Items);

Note that you also need to connect mongoose to the database via a mongoose.connect call which I don't see anywhere, but I'm assuming you're doing that outside of the scope of this code. Here's the full code I used to confirm this works:

var mongoose = require("mongoose");
var Schema  = mongoose.Schema;
var ObjectId = Schema.ObjectId;
var Items = new Schema({
    type            : { type : String , default:""},
    color           : { type : [String] , default:""},
    category_A      : { type : String , default:""},
    category_B      : { type : String , default:""},
    category_C      : { type : String , default:""},
});
var textSearch = require("mongoose-text-search");
Items.plugin(textSearch);
Items.index({
    type            :"text",
    color           :"text",
    category_A      :"text",
    category_B      :"text",
    category_C      :"text"
}, {
    name: "best_match_index",
    weights: {
        type: 5,
        color: 4,
    }
});
var ItemModel = mongoose.model('Item', Items);

mongoose.connect('mongodb://localhost/test', function (err) {
  ItemModel.textSearch('D', function (err, output) {
    if (err)
      console.log(err);
    else
      console.log(output);
    mongoose.disconnect();
  });
});

The created text search index looks like this in the shell:

test> db.items.getIndexes()
[
  {
    "v": 1,
    "key": {
      "_id": 1
    },
    "ns": "test.items",
    "name": "_id_"
  },
  {
    "v": 1,
    "key": {
      "_fts": "text",
      "_ftsx": 1
    },
    "ns": "test.items",
    "name": "best_match_index",
    "weights": {
      "category_A": 1,
      "category_B": 1,
      "category_C": 1,
      "color": 4,
      "type": 5
    },
    "background": true,
    "safe": null,
    "default_language": "english",
    "language_override": "language",
    "textIndexVersion": 1
  }
]