CODEWITHSUNDEEP
javascriptnode.jsaws-lambdaamazon-dynamodb
user6248190
user6248190

Reputation: 1269

Getting data from DynamoDB using multiple parameters in GET Request

I have a lambda function written in node, and I am trying to get data for a particular workout session.

The url looks something like this

workout/{workoutId}/sessions/{sessionId}

I know I can do something like the following if I just wanted to the workoutId

module.exports.getWorkoutSession = (event, context, callback) => {
  const { workoutId } = event.pathParameters;
  const params = {
    TableName: workoutTable,
    Key: {
      id: workoutId,
    },
  };

  return db.get(params).promise().then(res => {
      if(res.item) {callback(null, response(200, res.Item));} else {
          callback(null, response(404, {error: "workoutId not found"}))
      }
  })
};

but how can I modify this function so I can get the sessionData for a particular workout?

Upvotes: 0

Views: 1346

Answers (1)

Sarthak Jain
Sarthak Jain

Reputation: 2096

The answer depends on how the data is stored in Dynamo DB. If you have these two use cases -

  1. Getting data of all sessions of a workoutId (using workoutId from the event params) and
  2. Getting data of a specific session of a workout Id (using workoutId and sessionId from the event params)

Then these two can be solved by having the following table structure

Hash Key: workoutId
Range Key(Partition Key): sessionId

and the following code

/** API to get all sessions of a workout. Called by url workout/{workoutId} */
module.exports.getWorkoutSessions = async (event, context, callback) => {
    const { workoutId } = event.pathParameters;
    const params = {
        TableName: workoutTable,
        KeyConditionExpression: '#workoutId = :workoutId',
        ExpressionAttributeNames: {
            '#workoutId': 'workoutId'
        },
        ExpressionAttributeValues: {
            ':workoutId': workoutId
        }
    };

    const db = new AWS.DynamoDB.DocumentClient();
    try {
        const res = await db.query(params).promise();
        return res.Items;
    } catch (error) {
        console.error('Error while getting workout sessions', error);
        throw error;
    }
};

/** API to get a specific session of a workout. Called by url workout/{workoutId}/sessions/{sessionId} */
module.exports.getWorkoutSession = async (event, context, callback) => {
    const { workoutId, sessionId } = event.pathParameters;
    const params = {
        TableName: workoutTable,
        Key: {
            workoutId: workoutId,
            sessionId: sessionId
        }
    };

    const db = new AWS.DynamoDB.DocumentClient();
    try {
        return await db.getItem(params).promise();
    } catch (error) {
        console.error('Error while getting workout session', error);
        throw error;
    }
};

Upvotes: 2

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