How to fetch/scan all items from `AWS dynamodb` using node.js

Question

How to fetch/scan all items from AWS dynamodb using node.js. I am posting my code here.

var docClient = new aws.DynamoDB.DocumentClient();     var params = {     TableName:"users",     KeyConditionExpression:"user_status=:status",     ExpressionAttributeValues: {         ":status": "Y"     }     };      var queryExecute = function(callback) {         docClient.query(params,function(err,result) {             if(err) {                 console.log(err)                 callback(err);                 } else {                 console.log(result);                  if(result.LastEvaluatedKey) {                     params.ExclusiveStartKey = result.LastEvaluatedKey;                     queryExecute(callback);                     } else {                         callback(err,items);                     }                 }             });         }         queryExecute(callback);  

This is giving me below error.

ValidationException: Query condition missed key schema element: `user_id`. 

Here primary key is user_id. I don't want to use it with my query condition, because I need to set a value if I mentioned primary key in KeyConditionExpression. May be I am wrong. However please suggest me a good way to fetch all items from dynamodb, which is having user_status = "Y"

Answer 1

This is working for me:

export const scanTable = async (tableName) => {     const params = {         TableName: tableName,     };      const scanResults = [];     const items;     do{         items =  await documentClient.scan(params).promise();         items.Items.forEach((item) => scanResults.push(item));         params.ExclusiveStartKey  = items.LastEvaluatedKey;     }while(typeof items.LastEvaluatedKey !== "undefined");          return scanResults;  }; 

Answer 2

If you would like to get the data from DynamoDB without using Hash key value, you need to use Scan API.

Note: The Scan API reads all the items in the table to get the results. So, it is a costly operation in DynamoDB.

Alternate Approach : Use GSI

Scan Code for the above sceanario:-

var docClient = new AWS.DynamoDB.DocumentClient();  var params = {     TableName: "users",     FilterExpression: "#user_status = :user_status_val",     ExpressionAttributeNames: {         "#user_status": "user_status",     },     ExpressionAttributeValues: { ":user_status_val": 'somestatus' }  };  docClient.scan(params, onScan); var count = 0;  function onScan(err, data) {     if (err) {         console.error("Unable to scan the table. Error JSON:", JSON.stringify(err, null, 2));     } else {                 console.log("Scan succeeded.");         data.Items.forEach(function(itemdata) {            console.log("Item :", ++count,JSON.stringify(itemdata));         });          // continue scanning if we have more items         if (typeof data.LastEvaluatedKey != "undefined") {             console.log("Scanning for more...");             params.ExclusiveStartKey = data.LastEvaluatedKey;             docClient.scan(params, onScan);         }     } }