The think.model.mongo class inherit from think.model.base。
export default class extends think.model.mongo {
  getList(){
  }
}module.exports = think.model('mongo', {
  getList: function(){
  }
})Set indexes of field, before operate data it will set index automatically.
export default class extends think.model.mongo {
  init(...args){
    super.init(...args);
    // set indexes
    this.indexes = { 
    }
  }
}export default class extends think.model.mongo {
  init(...args){
    super.init(...args);
    // set index
    this.indexes = { 
      name: 1
    }
  }
}With $unique to set unique index, like:
export default class extends think.model.mongo {
  init(...args){
    super.init(...args);
    // set index 
    this.indexes = { 
      name: {$unique: 1}
    }
  }
}Multi-field index, like:
export default class extends think.model.mongo {
  init(...args){
    super.init(...args);
    // set index
    this.indexes = { 
      email: 1
      test: {
        name: 1,
        title: 1,
        $unique: 1
      }
    }
  }
}Primary key name, default is _id, get it with this.getPk.
Where condition in mongo model is different from relational database.
export default class extends think.model.mongo {
  where1(){
    return this.where({ type: "snacks" }).select();
  }
}export default class extends think.model.mongo {
  where1(){
    return this.where({ type: 'food', price: { $lt: 9.95 } }).select();
  }
}export default class extends think.model.mongo {
  where1(){
    return this.where({
     $or: [ { qty: { $gt: 100 } }, { price: { $lt: 9.95 } } ]
    }).select();
  }
  where2(){
    return this.where({
     type: 'food',
     $or: [ { qty: { $gt: 100 } }, { price: { $lt: 9.95 } } ]
   }).select();
  }
}export default class extends think.model.mongo {
  where1(){
    return this.where( {
      producer:
        {
          company: 'ABC123',
          address: '123 Street'
        }
    }).select();
  }
  where2(){
    return this.where({ 'producer.company': 'ABC123' } ).select();
  }
}export default class extends think.model.mongo {
  where1(){
    return this.where({ type: { $in: [ 'food', 'snacks' ] } }).select();
  }
}More details in https://docs.mongodb.org/manual/reference/operator/query/#query-selectors。
return {Promise}Get handler which operate current table.
export default class extends think.model.mongo {
  async getIndexes(){
    let collection = await this.collection();
    return collection.indexes();
  }
}Aggregate query, more details in https://docs.mongodb.org/manual/core/aggregation-introduction/。
mapReduce operate, more details in https://docs.mongodb.org/manual/core/map-reduce/。
indexes {Object} index optionsoptions {Object}Create indexes.
return {Promise}Get indexes.