ConditionalExpression DynamoDb Insert - amazon-dynamodb

I have the below data schema for my DynamoDb table. I am trying to append list subscribers on the condition if input = name (ex: input = my-topic2). There can be many maps in the “topics” list and I need to search for the map where the name = input and from there add the subscriber to that topic.
{
“server-id”: “123345678”,
“server-name”: “my-server”
“topics”: [
{
“name”: “my-topic”,
“subscribers”: []
},
{
“name”: “my-topic2”,
“subscribers”: [] //This is what I need to append on a condition that the input = “my-topic2”
}
]
}
I have the current following paeans I am using which appends “my-topic” subscribers.
params = {
ExpressionAttributeNames: {
"#T": "topics",
"#S": "subscribers"
},
ExpressionAttributeValues: {
":vals": [
message.author.id
]
},
Key: {
'server-id': serverID
},
ReturnValues: "ALL_NEW",
TableName: tableName,
UpdateExpression: "SET #T[0].#S = list_append(#T[0].#S, :vals)"
};

Related

when Updating items in DynamoDB giving error Invalid UpdateExpression using NodeJS

This is my handler function.
const updateOrder = (request) => {
const id = request.pathParams.id;
const orderObject = request.body;
if(!id || !orderObject)
throw new Error ('Please provide required id and object in order to update the order')
const params = {
TableName: "pizza-order",
Key: {
"orderId": id
},
UpdateExpression: "SET #n = :n, #a = :a ",
ExpressionAttributeNames: {
"#n": "pizza",
"#a": "address"
},
ConditionExpression: '' ,
ExpressionAttributeValues: {
":n": orderObject.pizza,
":a": orderObject.address,
},
};
return docClient.update(params).promise()
}
And the order Object is:
{
"pizza":"THe outstanding pizza",
"Address": "feni"
}
And it returns error like this. I don't know why it is happening. Very new to serverless development. anyone know the solution?
It was a very silly mistake. First in the order Object there is a typo:
{
"pizza":"THe outstanding pizza",
"address": "feni" //previously it was Address: "feni
}
And the second reason is ConditionExpression Can not be empty.
const updateOrder = (request) => {
const id = request.pathParams.id;
const orderObject = request.body;
if(!id || !orderObject)
throw new Error ('Please provide required id and object in order to update the order')
const params = {
TableName: "pizza-order",
Key: {
"orderId": id
},
UpdateExpression: "SET #n = :n, #a = :a ",
ExpressionAttributeNames: {
"#n": "pizza",
"#a": "address"
},
ConditionExpression: '' , // this can not be empty
ExpressionAttributeValues: {
":n": orderObject.pizza,
":a": orderObject.address,
},
};
return docClient.update(params).promise()
}

DynamoDb Nested Map Update

After working a bit with DynamoDb I’ve run into an issue that from what I’ve read so far is not really ideal for DynamoDb. So before I make the switch to RDS, I’d like to see if there’s anyway I can achieve what I need with DynamoDb. I’ve also thought about breaking this out into multiple tables for DynamoDb
Below of my Data schema. There is a list nested inside the item. I need to be able to append strings to the list.
{
“server-id”: “123345678”,
“server-name”: “my-server”
“topics”: [
{
“name”: “my-topic”,
“subscribers”: [] //This is what I need to append
}
]
}
Yes, this is possible.
var AWS = require('aws-sdk');
AWS.config.update({region: 'us-east-1'});
var ddb = new AWS.DynamoDB({apiVersion: '2012-08-10'});
var params = {
ExpressionAttributeNames: {
"#T": "topics",
"#S": "subscribers"
},
ExpressionAttributeValues: {
":vals": {
L: [
{ N: "123" },
{ N: "456" }
]
}
},
Key: {
'server-id': { S: '123345678' }
},
ReturnValues: "ALL_NEW",
TableName: 'dummy-table',
UpdateExpression: "SET #T[0].#S = list_append(#T[0].#S, :vals)"
};
ddb.updateItem(params, function(err, data) {
if (err) {
console.log("Error", err);
} else {
console.log("Success", data);
}
});

How to add items to a map in DynamoDB

I'm using the AWS.DynamoDB.DocumentClient with nodejs (lambda functions on AWS)
I've to a db called Translations, primary key Term, sort key Category.
Basically I'm trying to write data in like this:
{
Term: 'hello_there',
Category: 'common_phrases',
Translations: {
en-ca: 'Hello There!'
}
}
and I want to update Translations Map to perhaps add another language, or just modify the en-ca portion of the object.
I've tried the following:
let params = {
TableName: 'Translations',
Key: {
Term: 'hello_there',
Category: 'common_phrases',
},
UpdateExpression:
'SET Translations.#lang = list_append(Translations, :term)',
ExpressionAttributeValues: {
':term': 'french version',
},
ExpressionAttributeNames: {
'#lang': 'fr-ca',
},
}
But I get an error about the wrong operand type.
I've tried:
UpdateExpression:
'SET Translations.#lang = :term',
ExpressionAttributeValues: {
':term': 'french version',
},
ExpressionAttributeNames: {
'#lang': 'fr-ca',
},
But this overwrites the entire contents of the Translations field. Meaning that if I already had en-ca in there, now I would only have fr-ca.
I tried this as well, but also get an operand error:
{
UpdateExpression: 'ADD Translations :term',
ExpressionAttributeValues: {
':term': { 'fr-ff': 'frenchterm' },
},
Any suggestions on how to add/update items to the Translations Map?
Your SET expression was close, try something like this:
UpdateExpression:
'SET #trans.#lang = :term',
ExpressionAttributeValues: {
':term': 'french version',
},
ExpressionAttributeNames: {
'#trans': 'Translations`,
'#lang': 'fr-ca',
},

Add a number to a list item with DynamoDB

This is the DynamoDB table structure I'm working on:
{
"userId": "99999999-9999-9999-9999-999999999999",
"userProfile": {
"email": "myemail#gmail.com",
"firstName": "1234124",
"lastName": "123423",
},
"masterCards": [
{
"cardId": 101000000000001,
"cardImage": "logo.png",
"cardName": "VipCard1",
"cardWallet": "0xFDB17d12057b6Fe8c8c425D2DB88d8475674567"
},
{
"cardId": 102000000000002,
"cardImage": "logo.png",
"cardName": "VipCard2",
"cardWallet": "0xFDB17d12057b6Fe8c8c425D2DB88d8183454345"
},
{
"cardId": 103000000000003,
"cardImage": "logo.png",
"cardName": "VipCard3",
"cardWallet": "0xFDB17d12057b6Fe8c8c425D2DB88d8184345345"
}
],
}
I'm trying to increase the cardId field by one for the first list item with this Lambda function:
const dynamoDB = new AWS.DynamoDB({region: 'eu-central-1', apiVersion:'2012-08-10'});
const counterId="99999999-9999-9999-9999-999999999999"
const params = {
TableName:"FidelityCardsUsers",
Key: {"userId":{"S":counterId}},
UpdateExpression:"ADD #masterCards[0].#cardId :increment",
ExpressionAttributeNames:{
"#masterCards": "masterCards",
"#cardId": "cardId"
},
ExpressionAttributeValues:{":increment": {"N": "1"}}
}
dynamoDB.updateItem(params, function(err, data) {
if (err) {
console.log('error getting counter from DynamDB: ',err)
callback(err);
} else {
callback(null,data)
}
})
In return I get only a new top-level attribute named "mastercards[0].cardId[0]" with a value number set to 1.
I have tried to increment In an array and its work fine with AWS.DynamoDB.DocumentClient()
Example :
var AWS = require("aws-sdk");
var docClient = new AWS.DynamoDB.DocumentClient();
let params = {
TableName:'tableName',
Key: {
'venueId': 'VENUE_002'
},
UpdateExpression: "ADD #walk.#coordinates[0] :increment",
ExpressionAttributeNames: {
'#walk': 'walk',
'#coordinates': 'coordinates'
},
ExpressionAttributeValues: {
':increment': 1 // This is from the client
},
ReturnValues: 'UPDATED_NEW'
};
docClient.update(params, function (err, data) {
if (err) {
console.log('failure:updateShuttleDirection:failed');
console.log(err);
} else {
console.log('success:updateShuttleDirection:complete');
console.log(data);
}
});
Sample Data:
"walk": {
"coordinates": [
10,
20
],
"type": "Point"
},
I have tried to increment 10 to 11 and its work fine
Reading the doc here, it seems that:
the ADD action can only be used on top-level attributes, not nested
attributes.

How to create and populate lists in DynamoDB

I wish to create an Item in DynamoDB that is a list. This is my code:
var list_update_params = {
TableName: "table01",
Key: {
"MachineID": {
"S": MachineID
},
"Hour": {
"S": Hour
}
},
UpdateExpression: "set var01_list = list_append(var01_list, :ot)",
ExpressionAttributeValues: {
":ot": {"L": [{"N": var01}]}
},
ReturnValues: "NONE"
};
dynamodb.updateItem(list_update_params, function(err, data) {
if (err) console.log(err, err.stack);
else console.log("Updated List to DynamoDB");
});
The problem is list_append expects the attribute var01_list to already be present, but I wouldn't know at the first insert. Is there a technique where it'll let me create an insert a List attribute if one doesn't exist and append to it in later calls?
Got the answer from a similar post here.
UpdateExpression: "set var01_list= list_append(if_not_exists(var01_list, :empty_list), :h)",
ExpressionAttributeValues: {
":h": {"L": [{"N":var01}]},
":empty_list": {"L": []}
},
The key was using if_not_exists with list_append. Didn't know that could be done in this matter

Resources