Set

Introduction

Set represents DynamoDB's "SS", "NS", "BS" data types. With DynamoQL Every Set type must be defined with its items type.
items can be String, Number, Date or Buffer.

Define an Set

DynamoQL

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
  id: {
    type: String,
    primaryIndex: true,
    default: randomUUID
  },
  friendId: {
    type: Set,
    items: String
  }
} as const);

produced type

interface IUserSchema {
    id: string,
    friendId?: Set<string>
}

warning

items can not be a union type.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
  id: {
    type: String,
    primaryIndex: true,
    default: randomUUID
  },
  friendId: {
    type: Set,
    items: [String, Number]
  }
} as const);

However you can use union type for the entier Set type

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
  id: {
    type: String,
    primaryIndex: true,
    default: randomUUID
  },
  friendId: [
    {
      type: Set,
      items: String
    },
    {
      type: Set,
      items: Number
    },
  ]
  
} as const);

Options

- required

boolean which makes attribute as required or optionnal, default is false.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
  id: {
    type: String,
    primaryIndex: true,
    default: randomUUID
  },
  friendId: {
    type: Set,
    items: String,
    required: true
  }
} as const);

- default

To set a default value for an attribute use default option.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
  id: {
    type: String,
    primaryIndex: true,
    default: randomUUID
  },
  friendId: {
    type: Set,
    items: String,
    default: new Set(["steve", "john"])
  }
} as const);

default value's type must match defined Set's type.
Otherwise it will throw an error during dev time and runtime.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
 id: {
   type: String,
   primaryIndex: true,
   default: randomUUID
 },
 friendId: {
   type: Set,
   items: String,
   default: new Set([1, 2, 9]) // DynamoQLInvalidTypeException: "friendId[0]" expected to be "SS" received "NS".
 }
} as const);

default can also be a (async) function which accepts one argument (put Item value) and must return a Set of defined type.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
id: {
  type: String,
  primaryIndex: true,
  default: randomUUID
},
moderator: Boolean,
friendId: {
  type: Set,
  items: String,
  default: (item: Record<string, any>)=> {
      if(item.moderator) {
          return ["admin-id"]
      }
      return []
  }
}
} as const);

- validate

validate option allows you to manually validate provided value in put and update commands.
To return an error you should return a string which explains value invalidity. Any other returned value is considered as valid.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
id: {
  type: String,
  primaryIndex: true,
  default: randomUUID
},
moderator: Boolean,
friendId: {
  type: Set,
  items: String,
  validate: (self: Set<string>)=> {
      if(self.length > 10) {
          return "Error: Can not have more than 10 friends."
      }
  }
}
} as const);

- set

To modify a value before storing it use set option.
set (async) function accepts 3 arguments:

1. self provided value.
2. item entier put Item object.
3. setterInfo an optionnal value provided inside in put, batchPut, batchWrite, transactWrite command's options.

set will not be called if attribute doesn't exists in put Item object.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
id: {
  type: String,
  primaryIndex: true,
  default: randomUUID
},
moderator: Boolean,
friendId: {
  type: Set,
  items: String,
  set: (self: Set<string>, item: Record<string, any>, setterInfo?: any)=> {

      if(item.moderator && setterInfo?.someCondition) {
       return new Set(["admin"])
      }

      return self
  }
}
} as const);

- get

When reteving an Item we can transform field's value with get option.

get (async) function accepts 3 arguments:

1. self retrieved value.
2. item entier retrieved Item object.
3. getterInfo an optionnal value provided inside get, batchGet, transactGet, query, scan command's options.

get can return anything.
get will not be called if attribute doesn't exists in stored Item.

import { Schema } from "dynamoql";
import { randomUUID } from "crypto";

const userSchema = new Schema({
id: {
  type: String,
  primaryIndex: true,
  default: randomUUID
},
moderator: Boolean,
friendId: {
  type: Set,
  items: String,
  get: (self: Set<string>, item: Record<string, any>, getterInfo?: any)=> {
       return Array.from(self.values()).map(x=> doSomething(x))
  }
}
} as const);

info

get returned value's type affects Item type when retriving Item(s) from DynamoDB.

- description

add any information to the Schema for your personal usage.

Condition expression

Condition expression are not part of Schema but they are based on your defined Schema.
They are used in various DynamoDB operations to check for some condition(s).
DynamoQL supports all DynamoDB Condition expression.

- equals

{
  friendId: new Set(["user-1"])
}

or

{
  friendId: {
    $eq: new Set(["user-1"])
  }
}

- not equals

{
  friendId: {
    $neq: new Set(["user-1"])
  }
}

- attribute exists

$exists can be true or false.

{
  friendId: {
    $exists: true
  }
}

- includes

Checks if stored Set contains provided value.

{
  friendId: {
    $includes: "user-1"
  }
}

- Set length

Checks for stored Set's length.

{
  friendId: {
    $size: 1
  }
}

$size can also be any valid numeric comparison operator.

{
  friendId: {
    $size: {
      $gt: 0
    }
  }
}

Possible operators are $eq, $neq, $gt, $gte, $lt, $lte, $in, $between.

- attribute type

Checks for stored attribute type.

{
  friendId: {
    $type: {
      type: Set,
      items: String
    }
  }
}

$type can be String, Number, Boolean, Null, Buffer, Object, Array, or {type: Set, items: String | Number | Buffer }

- in

Checks if provided array includes stored Set.

{
  friendId: {
    $in: ["Steve", 214, "Sara", false, "John", "Mike", null, new Set(["user-1"])]
  }
}

- AND

Checks for multiple conditions. Condition is valid if ALL specified conditions are satisfied.

{
  friendId: {
    $and: [
      {
        $size: 6
      },
      {
        $includes: "user-1"
      }
    ]
  }
}

shorthand style

{
  friendId: {
    $size: 6,
    $includes: "user-1"
  }
}

- OR

Checks for multiple conditions. Condition is valid if at least one of specified conditions is satisfied.

{
  friendId: {
    $or: [
      {
        $size: 6
      },
      {
        $includes: "user-1"
      }
    ]
  }
}

- NOT

Condition is valid if specified condition is NOT satisfied.

{
  friendId: {
    $not: {
      $includes: "user-1"
    }
  }
}

$not accepts any Condition expression.

When multiple conditions are provided inside $not: {} they are considered as $and condition.

{
  friendId: {
    $not: {
      $size: 6,
      $includes: "user-1"
    }
  }
}

longhand equivalent is:

{
  friendId: {
    $not: {
      $and: [
        {
          $size: 6
        },
        {
          $includes: "user-1"
        }
      ]
    }
  }
}

Update expressions

Like Condition expression, Update expressions are not part of Schema, but they are based on defined Schema.

Update expressions are used in update, transactUpdate and transactWrite operations.

DynamoQL supports all DynamoDB update operations.

- set

$set replaces stored Set by provided Set.

{
  friendId: {
    $set: new Set(["user-1"])
  }
}

shorthand version is

{
  friendId: new Set(["user-1"])
}

- if not exists

$ifNotExists sets provided Set if attribute do not exists in stored item.
$ifNotExists dont affects Condition expression and is attribute specific.
If attribute exists, stored value stays unchanged.

{
  friendId: {
    $ifNotExists: new Set(["user-1"])
  }
}

- add

Adds value(s) to stored Set.

{
  friendId: {
    $add: "user-1"
  }
}

Add multiple values.

{
  friendId: {
    $add: ["user-1", "user-2"]
  }
}

- delete

Deletes value(s) from stored Set.

{
  friendId: {
    $delete: "user-1"
  }
}

Delete multiple values.

{
  friendId: {
    $delete: ["user-1", "user-2"]
  }
}