[Question] How to only update if email dosn't exist in table

[sp90]

Hey,

Im searching for a solution to a problem:

How to only update an item, but only if the email dosn't exist in the whole table?

[cdhowie]

I would need to see your schema as well as some example data to be able to answer this question.

[sp90]

This is my model:

// Users V2
exports.UsersV2 = dynogels.define('Users', {
  // Settings
  tableName: 'Users-v2',
  hashKey: 'user_id',
  timestamps : true,

  // Schema
  schema: {
    user_id: dynogels.types.uuid(),

    // items of interest
    org_id: Joi.string(),
    email: Joi.string().email(),
    phone_number: Joi.string(),

    // Rest
    code: Joi.string(),
    department_id: Joi.string(),
    internal_user_name: Joi.string(),
    job_title: Joi.string(),
    lang: Joi.string(),
    password: Joi.string(),
    linkedin_id: Joi.string(),
    image_key: Joi.string(),
    user_name: Joi.string(),
    user_role: Joi.string(),
  },

  // Index
  indexes: [{
    hashKey: 'org_id',
    rangeKey: 'email',
    name: 'email-index',
    type: 'global'
  }, {
    hashKey: 'org_id',
    rangeKey: 'phone_number',
    name: 'phone_number-index',
    type: 'global'
  }, {
    hashKey: 'email',
    name: 'just-email-index',
    type: 'global'
  }]
});

And then i try to update the email, but only if it dosn't exist in the table column called email

This is how i try to do it:

UsersV2.update({
  user_id: 'SOME_ID',
  email: 'example@example.com'
}, { 
  expected: { 
    email: { 
      Exists: false 
    } 
  } 
}, function(err, resultData) {
  // Result
});

[jkav77]

I think what you need is to use the expected parameter. There is an example in the readme under Updating.

On December 18, 2017 at 00:51:16, Simon Dragsbæk Petersen (notifications@github.com(mailto:notifications@github.com)) wrote:

This is my model:

// Users V2 exports.UsersV2 = dynogels.define('Users', { // Settings tableName: 'Users-v2', hashKey: 'user_id', timestamps : true, // Schema schema: { user_id: dynogels.types.uuid(), // items of interest org_id: Joi.string(), email: Joi.string().email(), phone_number: Joi.string(), // Rest code: Joi.string(), department_id: Joi.string(), internal_user_name: Joi.string(), job_title: Joi.string(), lang: Joi.string(), password: Joi.string(), linkedin_id: Joi.string(), image_key: Joi.string(), user_name: Joi.string(), user_role: Joi.string(), }, // Index indexes: [{ hashKey: 'org_id', rangeKey: 'email', name: 'email-index', type: 'global' }, { hashKey: 'org_id', rangeKey: 'phone_number', name: 'phone_number-index', type: 'global' }, { hashKey: 'email', name: 'just-email-index', type: 'global' }] });

And then i try to update the email, but only if it dosn't exist in the table column called email

This is how i try to do it:

UsersV2.update({ user_id: 'SOME_ID', email: 'example@example.com' }, { expected: { email: { Exists: false } } }, function(err, resultData) { // Result });

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[sp90]

@dangerginger in the given example thats what im doing, but it dosn't work as expected :/

[cdhowie]

@sp90 It sounds like you want to update the user with ID SOME_ID to have the given email address, only if that email address isn't present in any other record? DynamoDB cannot do that. The expected attribute applies only to the record being updated.

[jkav77]

Oh yeah there is no way to enforce uniqueness in dynamodb that I know of except for the hash key without a range key. Your options as I see them are:

• Query first to see if the email exists in the table, then conditionally write as you like. This is the easiest to implement.
• Use the email as a hash key for the model (and don't use a range key). This might not be possible for you if you need the uuid.
• Use a separate table for email addresses where the email address is the hash key. The record for each email could be a uuid for the use that owns it.

But anyways this is a dynamodb limitation and nothing we can really fix with dynogels.