如何根据特定条件在猫鼬验证中创建错误数组？

Question

i'm trying to generate array of errors based on certain conditions , how can i achieve that , postman arrises this : "Cannot read properties of undefined (reading 'push')"

  username: {
    type: String,
    required: [true, "username is required"],
    // minlength: 6,
    unique: true,
    // match: [
    //   /^(?=.{3,20}$)(?![_.])(?!.*[_.]{2})[a-zA-Z0-9._]+(?<![_.])$/,
    //   "username shouldn't include . or _ and at least 3 letters and at maximum 20 letters",
    // ],
    validate: {
      errors: [],
      validator: function (username) {
        if (username.length < 10) {
          this.errors.push("username cannot be less than 3 characters");
        }
        if (username.match(/(?![_.])(?!.*[_.]{2})[a-zA-Z0-9._]+(?<![_.])$/)) {
          this.errors.push(`username shouldn't begin or end with . or _ `);
        }
      },
      message: this.errors,
    },
  },

Answer 1

Create an array in the validator function and throw this array as new Error() . Then use this array in the callback of the save() function.

validate

validate: {
        validator: function (username) {
            let errors = []
            if (username.length < 3)
                errors.push("username cannot be less than 3 characters")

            if (username.match(/(?![_.])(?!.*[_.]{2})[a-zA-Z0-9._]+(?<![_.])$/))
                errors.push("username shouldn't begin or end with . or _ ")

            if (errors.length > 0)
                throw new Error(errors)
        }
    }

save

newUser.save((err, user) => {
    if (err) {
        let errors = Object.values(err.errors)[0].properties.message.split(',')
        return res.status(400).json({
            success: false,
            err: errors.length > 1 ? errors : errors[0]
        })
    }
    else ...
})