Appsync pagination

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appsync pagination

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I would like to be able to filter a pagination result using query operation before the limit is taken into consideration.

Is there any suggestion to get right pagination on filtered results? Note: I have already tried Global Secondary Index but it didn't work in my case Because I have 5 different attributes to filter and limit. Unfortunatelly DynamoDB is not capable to do this, once you do Query on one of your indexes, it will read every single item that satisfies your partition and sort key. Lets check your example - You have boolean and you have index over that field. If you set up limit, it will read only that number of items and then it stops.

You wrote that you have 5 parameters you want to query. The workaround that is used to address these limitations is to create and manage extra fields that have combination of parameters you want to query. Lets say you have table of users and you have there gender, age, name, surname and position.

Lets say its huge database, so you have to think about amount of data you can load. Then if you want to use DynamoDB, you have to think about all queries you want to do. You most likely want to search by name and surname, so you create index with surname as partition key and name as sort key in such case you can search by surname or by both surname and name.

It can work for lot of names, but you found out that some name combinations are too common and you need to filter by position as well. In such case, you create new field column called i. Then you can make another index, that has name-surname as partition key and position as sort key. Now you can use it for such searches. However you found out, that for some name-surname-position combination you get too many results and you dont want to handle it on application level and you want to limit results by age as well.

Then you can create index with name-surname-position as partition key and age as sort key.

Building Serverless React GraphQL Applications with AWS AppSync

At this moment you can also figure out that your old name-surname field and index can be removed as it server no purposes anymore name and surname are handled by another index and for searching just name-surname-position you can use this index. You want to query by gender as well sometimes? Its probably better to handle that in application level or extra filter in db query rather than creating new index that must be handled and payed for.

Because for extra index you would have to pay for every single insert, but this filter will be used only from time to time.

Also when someone searches already by name, surname and position you dont expect that much results anyway, so if you get 20 all genders or just 10 male only results does not make much difference.

How exactly you use it depends on your business logic. Very important note: DynamoDB is very simple database that can only do very simple queries. It has little more functionality than Redis but a lot less functionality than traditional databases.

VTL AppSync resolver Request Mapping Template:

Learn more. Asked 8 days ago. Active 7 days ago. Viewed 29 times. Taha Farooqui.In a GraphQL query, the client specifies how the data is to be structured when it is returned by the server. This makes it possible for the client to query only for the data it needs, in the format that it needs it in.

GraphQL Subscriptions are simple statements in the application code that tell the service what data should be updated in real-time. When combined with AWS AppSync the DataStore can leverage advanced versioning, conflict detection and resolution in the cloud allowing to automatically merge data from different clients as well as providing data consistency and integrity.

AWS AppSync gives client applications the ability to specify data requirements with GraphQL so that only the needed data is fetched, allowing for both server and client filtering. Being fully managed, it eliminates the operational overhead of managing cache clusters. By providing the flexibility to selectively cache data fields and operations defined in the GraphQL schema with customizable expiration, data caching further enables developers to configure optimal performance for their business needs.

AWS AppSync allows several levels of data access and authorization depending on the needs of an application. Simple access can be protected by a key and more restrictive permission can be done with AWS Identity and Access Management using Roles. Customers can use the Group functionality for logical organization of users and roles as well as OAuth features for application access. Immediate updates across clients and devices. Interact with and update your data, even when offline, with the Amplify DataStore.

Preconfigured access to AWS data sources. Cache your data that doesn't change frequently for improved performance. Control your data. Ready to get started? Have more questions? Page Content.Are you in the process of evaluating its benefits and drawbacks at scale?

Rather than making requests to various endpoints to get different parts of the data needed to build a webpage, developers can issue a single request to a GraphQL API and immediately get back all the data they need. This model reduces the complexity of web applications and improves the experience for website visitors with faster load times.

Instead, the backend is usually composed of multiple microservices, and the GraphQL API layer is responsible for gathering all the necessary data from the various applications and returning the combined result to the API requester. Under the hood, AppSync consists of a GraphQL proxy—a service that receives and parses all the GraphQL requests—and of multiple subsystems for handling each specific request type.

appsync pagination

The supported request types are queries for getting data from the APImutations for changing data via the APIand subscriptions long-lived connections for streaming data from the API.

In addition, AppSync provides a convenient way to connect each resolver function to a data source. Amplify achieves this by providing a library of reusable components and utilities. The component supports all available data sources and authentication methods while giving you the excellent Serverless Framework developer experience when working with AppSync.

Many APIs managed with AppSync also rely on AWS Lambda functions as their data sources, and the Serverless Framework is a great fit for creating those Lambda functions, from design through deployment to monitoring and debugging. As a developer, how do you stand to benefit the most from using AppSync? We believe there are three main advantages:.

AppSync allows you to skip the creation of your own GraphQL resolvers and data-source connections, resulting in significant time savings when standing up new GraphQL APIs and in faster iteration once you have customers, internal or external, using your APIs.

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Real-time subscriptions and offline functionality built in. Using AppSync allows for GraphQL subscriptions, which are a great way to build applications that always present the most up-to-date state of the data.

appsync pagination

When using AppSync with the Amplify framework, you can combine subscriptions with offline functionality to create auto-updating web and mobile apps that can correctly handle unstable mobile network connections without much additional work. Integrations with core AWS services. This speeds up development for your teams using AppSync, allowing them to focus more on business logic and less on connection layers for the underlying services.

Using AppSync certainly has some drawbacks, and you should consider the following carefully before using AppSync in production. Much of the useful functionality of AppSync is available only when using specialized GraphQL tooling, like the Amplify framework.

This is a result of the complexity of the GraphQL protocol and its real-world implementations. This means that getting the maximum benefit out of using GraphQL in general and AppSync specifically will bring with it additional dependencies and a steep learning curve. Lack of transparency in performance. AppSync can add significant overhead to your API response times, and in certain cases e.

Not all data sources are supported out of the box. Vendor lock-in. With proprietary products you gain efficiency at the cost of flexibility.

This is a choice best made with your team while considering exactly what you are trying to achieve. If you are building a complex web application and want to make it quick and responsive both at load time and during normal operation, then GraphQL may be a good choice.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. It seems OK to use IN for query comparison operator; however, how can I pass a String List as a parameter and fetch the results whose IDs are among those parameters supplied?

I try to test your scenario and come up with a solution using contains function. You can pass a list of keys in a single query and return the results from a table. You need use the same argument name in both places. However, you want the id values to be contained within quotes. AWS AppSync provides another utility method for this purpose. Let me know if this resolved your issue. Here is the reference to the Resolver Mapping Template Utilities. This has to be a filter expression and since you don't have a key condition, this may even have to be a scan instead of a query.

Learn more. Asked 1 year, 6 months ago.

AWS AppSync - The Ultimate Guide

Active 1 year, 4 months ago. Viewed 2k times. EDIT: Corrected variable name typo. Active Oldest Votes. KoingDev KoingDev 4 4 silver badges 10 10 bronze badges.

Thanks for the approach, but I avoid using filter section as it may corrupt the results when used with pagination. Did you try contains in query expression i. BatchGetItem looks decent, but I query the performance. Gonna test it. I think there could be 2 issues here: Your arguments in the listItemsWithIdList query accepts an argument named userIds.

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Shankar Raju Shankar Raju 3, 6 6 gold badges 26 26 silver badges 49 49 bronze badges. I guess IN is not allowed for query, this link also tells about it. Hopefully you have already resolved it. Sachin Ahuja Sachin Ahuja 1. Thanks, the reason I avoided Scan was its filter is applied after the pagination see the usage of limit and nextToken in the OP.

You cannot decently get first, let's say 5 results, it may return 3 out of total 10 with Scan. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.

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We're sorry we let you down. If you've got a moment, please tell us how we can make the documentation better. Choose the button at the top to run your mutation.

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After the run is complete, the result from your selection set that is, idnamedescriptionand priority appear on the right. The data is also in the Amazon DynamoDB table for your data source, which you can verify using the console. This returns your data, but it only returns the two fields id and name from your selection set.

Note: If you are getting an error such as Validation error of type FieldUndefinedyou might have followed the instructions for setting up relations and pagination. If so, use the queries in the next section. If you have set up the advanced schema with relations and pagination, your getTodos query will look a bit different. First, add a comment to your todo as follows:.

In this case, the commentid is automatically created. Add a few more todos and commentsset the limit to 2 records, and then run getTodos as follows:.

appsync pagination

Only two todos come back with the comments because you specified limit:2 in the arguments. A long string should be returned for the nextToken field. For example:. In a client application you would pass this token through as an argument based on your pagination flow and logic. For more information, see the following sections:. Data Sources tutorials. Resolvers and Mapping Templates. Building Client Applications. Javascript is disabled or is unavailable in your browser.

Please refer to your browser's Help pages for instructions. Relations and Pagination Next Steps.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. If the subset returned does not contain the full table, a LastEvaluatedKey value is returned.

You use this value as the ExclusiveStartKey in the next query. And so on You can provide 'page-size' in you query to set the result set size. If response does't contain 'LastEvaluatedKey' it means there are no results left to fetch. DynamoDB Pagination. Also in case, the application is serverless, using service like Lambda, it will be not be possible to maintain the state on the server. The other side is the client implementation will become very complex. When the API client specifies the start index, fetch all the keys from the table and store it into an array.

Make use of the ExclusiveStartKey and fetch the number of records, as specified in the page length. If the start index parameter is not present, the above steps are not needed, we don't need to specify the ExclusiveStartKey in the scan operation. We will need additional memory to store the Ids and the indexes. Additional database scan operations one or multiple to fetch the keys. But I feel this will be very easy approach for the clients, which are using our APIs.

The backward scan will work seamlessly. If the user wants to see "nth" page, this will be possible. Learn more. Asked 8 years, 2 months ago. Active 26 days ago.AppSync uses GraphQL.

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GraphQL is a language for APIs that enables you to query and manipulate data easily through an intuitive and flexible syntax. GraphQL provides a syntax to describe data requirements and interactions, allowing you to ask for exactly what you need and get back predictable results. This article aims at providing strategy on how to query data in the DynamoDB table with sorting and pagination. The pagination strategy used is called cursor-based pagination. Curser based pagination helps to avoid the problems of limit-offset pagination.

Shifting of data on insertion and on deletion occurs while paginating in a limit-offset way, this is not ideal for real-time data. Whats is curser based pagination? By using this strategy major pitfalls of limit-offset pagination can be avoided. Choose Build from scratch.

After creation goto edit schema and add schema. What is SDL Schema definition language? Schema expects query. Subscribtion and Mutation can be also provided to subscribe to and mutate DynamoDB data source. Data Source should be attached to the schema using the resolvers. If tables are not created, create them.

Add resolvers, in this case, we can add resolvers for the get query. Resolvers for the query for getting tasks, can be added after creating it. Resolvers are the ones that translate GraphQL requests or responses to Data sources.

In this case, create two tables employee and tasks. The combination of both keys forms primary key. Primary key is unique. A connection is a way to get all of the nodes that are connected to another node in a specific way. In this case, we want to get all of the task nodes connected to our employees. Connection of an employee to multiple tasks can be defined in the following way in Graph. The TaskConnection type has an array of tasks.


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