so i have a spring boot application and my data source is MySQL via JPA. I am trying to introduce Odata queries to my API's and then fetch data based on those odata params. I was wondering if there are any utils or external libraries i can use to parse the odata query then construct the JPA Specification. I have looked into olingo but im not sure if it is exactly what i am looking for. I was thinking of parsing the query text, and constructing the jpa specifications manually(maybe use reflection is necessary), but if anyone has any tips or advice on how to better approach this it would be much appreciated!!
I was thinking of doing something similar to this but with odata instead. Only issue i see is making this dynamic enough to handle every complex odata query coming in.
https://www.baeldung.com/rest-api-search-language-spring-data-specifications
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In My Application, Using the below technologies
Spring boot 2.7.x
Cassandra
spring batch 5. x
java 11
As part of this, I need to extract data from the Cassandra database and need to write out the file
so here I need to use queries to fetch data so
just want to know what is the best way to maintain all queries at one place so any query changes come in the future, I shouldn't build the app rather just need to modify the query.
Using a repository class is necessary. If you are using JPA i recommend using a repository for each Entity class. With JDBC it is possible to create a single repository which contains all the queries. To access the query methodes i would use a service class. In this way your code is structured well and maintainable for future changes.
Searched over the net but unable to find the satisfying approach.
I am new to spring boot and aware of starter dependancies,
I want to develop a springboot app using elastic search as a storage system.
Wherever i searched i found that somewhere my service class will have to implement some interface from springframework for ES crud operations.
Is there any other way without implementing or extending the components.
I myself want to create transport client and want to query ES by my code or methods not by overidden ones.
Please if you ahve ever seen any projects you can redirect me to that link .
Thanks.
Assuming I understand you correctly, you can use the Elasticsearch REST client: https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-low.html
You supply the JSON entities for the queries and parse the responses yourself. Its pretty basic in what it does, so you're not dependent on a lot of third party stuff to perform operations.
I have to implement some application by using springframework.
All i have to do is just select from repository (no RDBMS, maybe lucene or elastic search core) and Display some view pages for customers. that is not save or update but read.
What is the best way to select for repositories in spring framework ?
You can use spring-data-elasticsearch which is the Spring Data implementation for ElasticSearch.
In order to get started, you may like to refer to https://www.mkyong.com/spring-boot/spring-boot-spring-data-elasticsearch-example/ which explains the integration with an example. Although it is a bit old but provide you with enough information to get it working.
I want to access a Neo4j DB with Java and wanted to know what the preferred way to do this is. I just want to write a quite simple data structure to the DB.
http://neo4j.com/developer/java/ gives following options:
JDBC
Hibernate OGM
Spring Data
Rest API via Unmanaged Extensions
I looked into accessing Neo4J with JDBC and Hibernate OGM. It seems that its not worth it to use for me. JDBC gives me some trouble. So should i go with the REST way or try to fix my JDBC problems?
The JDBC driver is really a wrapper around the REST interface (as of neo4j 2.3). There is a example application how to use it. Should suffice for very simple use.
Then there is neo4j-ogm (different from Hibernate OGM) - this is an object graph mapping library, similar to hibernate in ORM world. This has minimal external dependencies and is very easy to use - ideal for cases where you want to map couple of objects into graph.
Then there is the Spring Data Neo4j project, which since version 4 uses neo4j-ogm for mapping, but adds other Spring data features, like repositories, derived finder queries, transactions ...
We are planning to use oData as a entity standard for rest api layer. The data provided by web api are taken from various subsystems and layers of cache(memcache) involved. My fear is how the basic entity model without EF can support the oData implementation of pagination and filtering. I want the ability to restrict the retrieval record limit at the underlying susbsytem level not at the api controller level. Any pointers would be useful. Thanks.
I have written a blog post on doing OData querying over non-IQueryable backends. I have picked HQL as the target query language. http://blogs.msdn.com/b/webdev/archive/2013/02/25/translating-odata-queries-to-hql.aspx
That should help you to understand how easy it is to support OData queries using web API.