Kotlin Support

[lucasleon2107]

I using Spring Boot (3.0.2) with JDK 17, Kotlin (1.8.20) and the latest version of Redis OM (0.8.2). I configured the annotation processor using kapt. Here's the snippet:

<plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <extensions>true</extensions>
                <executions>
                    <execution>
                        <id>kapt</id>
                        <configuration>
                            <sourceDirs>
                                <sourceDir>src/main/kotlin</sourceDir>
                            </sourceDirs>
                            <annotationProcessorPaths>
                                <annotationProcessorPath>
                                    <groupId>com.redis.om</groupId>
                                    <artifactId>redis-om-spring</artifactId>
                                    <version>0.8.0</version>
                                </annotationProcessorPath>
                            </annotationProcessorPaths>
                        </configuration>
                    </execution>
                </executions>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>

This is the class that is being generated:

public final class UserInfoHash$ {
  public static MetamodelField<UserInfoHash, String> _KEY;

  static {
    try {
      _KEY = new MetamodelField<UserInfoHash, String>("__key", String.class, true);
    } catch(NoSuchFieldException | SecurityException e) {
      System.err.println(e.getMessage());
    }
  }
}

But I'm getting the following error: exception java.lang.NoSuchFieldException is never thrown in body of corresponding try statement

[bsbodden]

Lucas, can you post the code for the UserInfoHash - I think I see what the problem is. I'm assuming that there will be other fields besides the id. But please post the code or similar code so that I can confirm.

[lucasleon2107]

Sorry, I'm not near my computer right now, but it's a User data class with the @Document annotation, a String @Id that I'm setting myself, not autogenerated. Name and last name with @Searchable and a code String field with @Indexed. I hope that helps

[lucasleon2107]

This is the class

@Document
data class UserInfoHash(
    @Id
    val accountId: String = "",
    @Searchable
    val firstName: String? = null,
    @Searchable
    val lastName: String? = null,
    @Indexed
    val code: String? = null
)

[lucasleon2107]

@bsbodden any updates?

[bsbodden]

Not yet, there hasn't been much testing for Kotlin so I'm in the process of building some tests.

[lucasleon2107]

@bsbodden is there a way that I can make a query by multiple optional query params? I want to filter by name or last name and maybe other additional fields that I could add that will come from the controller

[lucasleon2107]

@bsbodden I assume I have to use Predicates. Can you show me an example of how to achieve that?

[bsbodden]

@bsbodden is there a way that I can make a query by multiple optional query params? I want to filter by name or last name and maybe other additional fields that I could add that will come from the controller

Lucas, stop by our discord server http://discord.gg/redis and I can help you there. On the issue on this page, it looks like we might need to use the "all open plugin" and make modifications to OM to support Kotlin https://kotlinlang.org/docs/all-open-plugin.html#maven

So in the meantime, unfortunately, I would assume that there is no Kotlin support until announced. I'm building a comprehensive test suite to validate the Kotlin support and I would expect it out in 0.8.4 or so.

[bsbodden]

@lucasleon2107 I think I have a running example working now. It was just a matter of getting kapt to behave correctly. I will post a link to a sample repo later today.

[bsbodden]

@lucasleon2107 see https://github.com/redis-developer/redis-om-spring-kotlin-skeleton-app

[lucasleon2107]

@bsbodden This great, thanks! I'll try it later today. I have a question. Do you have an example of how to make queries with the Java Predicate class? I did some tests, but they currently didn't work for me

[bsbodden]

There are some examples in that repo.

[lucasleon2107]

I tested your repo, and it does not consistently work for me. I got it to work once, but then I ran mvn clean compile and also tested with just ./mvnw spring-boot:run, but I'm getting this error:

cannot find symbol
[ERROR]   symbol:   class Person
[ERROR]   location: class com.redis.om.skeleton.models.Person$

Also, I copied the kapt configuration from the repo to my project, but I'm still getting exception java.lang.NoSuchFieldException is never thrown in body of corresponding try statement

Regarding the filtering with the Java Predicate class, according to the filter method, it can receive the following classes:

• SearchFieldPredicate
• Predicate
• String

But in your repo, there are only examples with SearchFieldPredicate. I would like to know how to send Predicate to achieve filtering since the MetaModel generation is not working for me.

[lucasleon2107]

I made a change in the kotlin-maven-plugin . I removed <extensions>true</extensions> and added this to the execution:

<goals>
    <goal>kapt</goal>
</goals>

I'm still getting the cannot find symbol error, but at least the metamodel is generated without causing issues. Also, I just noticed that I needed to set all fields as var to get all the fields generated in the metamodel. I'll continue my tests and let you know if I find any more issues.

[lucasleon2107]

I tested the findByFirstNameAndLastName method in your repo by sending null parameters, and I got this error:

Cannot invoke "Object.getClass()" because "maybeText" is null

In my case that I'm doing queries with contains I get this error when sending a null param:

Error details: Cannot invoke "Object.toString()" because the return value of "com.redis.om.spring.search.stream.predicates.fulltext.LikePredicate.getValue()" is null

[bsbodden]

Thanks, if you get it all working, can you send a PR to that repo? I'll add some null checking on those predicates on the next release.

[lucasleon2107]

@bsbodden, is there a way to bypass those errors with the current version?

[lucasleon2107]

Hey @bsbodden, could you help me by sharing a code snippet illustrating how to implement filtering based on optional query parameters? It would be great if the snippet were compatible with the current version. Thanks!

[lucasleon2107]

So I tried to achieve that with the Example class, but RedisDocumentRepository does not support it. Disappointing

[bsbodden]

Obviously much more testing required for full Kotlin support. Likely a 1.0.0 feature.

[lucasleon2107]

I understand, but I don't think this is a Kotlin issue. Does sending null for MetaModels predicates or sending a Predicate work on Java?

[lucasleon2107]

@bsbodden I achieved what I wanted by doing something like this:

fun search(
        firstName: String? = null,
        lastName: String? = null,
        code: String? = null
    ): List<UserInfoHash> {
        var entityStream = entityStream.of(UserInfoHash::class.java)

        val predicates = mutableListOf<SearchFieldPredicate<UserInfoHash, String>>()

        code?.let {
            val predicate = `UserInfoHash $`.CODE.eq(code.uppercase())
            predicates.add(predicate)
        }

        firstName?.let {
            val predicate = `UserInfoHash$`.FIRST_NAME.containing(firstName.uppercase())
            predicates.add(predicate)
        }

        lastName?.let {
            val predicate = `UserInfoHash$`.LAST_NAME.containing(lastName.uppercase())
            predicates.add(predicate)
        }

        if (predicates.isNotEmpty()) {
            val combinedPredicates = combinePredicates(predicates)
            entityStream = entityStream.filter(combinedPredicates)
        }

        return entityStream.collect(Collectors.toList())
    }

    private fun <E, T> combinePredicates(predicates: List<SearchFieldPredicate<E, T>>): SearchFieldPredicate<E, T> {
        return object : SearchFieldPredicate<E, T> {
            override fun getSearchFieldType(): Schema.FieldType? {
                return null
            }

            override fun getField(): Field? {
                return null
            }

            override fun getSearchAlias(): String? {
                return null
            }

            override fun test(t: T): Boolean {
                return predicates.all { it.test(t) }
            }

            override fun apply(node: Node): Node {
                var currentNode = node
                for (predicate in predicates) {
                    currentNode = predicate.apply(currentNode)
                }
                return currentNode
            }
        }
    }

It's not ideal, but at least it works. I also noticed that the containing query needs 3 to 4 characters to make a match. Is there a way where I can send just one character to get results?

[bsbodden]

• The null checks will be added to the Predicates that were missing, I think that should help a bit - this will be in v0.8.3-SNAPSHOT next publish.
• RediSearch has a default minimum prefix set to 2, but you can change it globally using FT.CONFIG SET MINPREFIX 1
• If you get the Maven build to work correctly please send a PR, we could use the help!
• I'll take a look the predicate above to see if I can integrate it, after I get the null checking in place

[lucasleon2107]

Well, it looks like the inconsistent behavior is still present. I tried that new config that I mentioned, but I still get this error after mvn clean compile:

cannot find symbol
symbol:   class Person
location: class com.redis.om.skeleton.models.Person$

It still generates the MetaModel and works when I run the project with IntelliJ. And even though subsequent mvn compile executions do not create more errors, it always fails when I run mvn clean compile, breaking my Jenkins pipeline because it starts from a clean state.

[bsbodden]

The issue is that the order should be:

• Generate sources (metamodels)
• Compile main sources
• Compile metamodels

This somehow happens in the right order with a regular Maven build using just Java, but it is out of order when using KAPT. I'll figure that out soon.

[lucasleon2107]

I just fixed it by adding this plugin

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>3.2.0</version>
    <executions>
        <execution>
            <id>add-source</id>
            <phase>generate-sources</phase>
            <goals>
                <goal>add-source</goal>
            </goals>
            <configuration>
                <sources>
                    <source>src/main/kotlin</source>
                </sources>
            </configuration>
        </execution>
    </executions>
</plugin>

[lucasleon2107]

I already created the PR. Also, I ran FT.CONFIG SET MINPREFIX 1, but I'm still needed to send 3 characters or sometimes even 4 when doing a containing query

[bsbodden]

In your example, you have:

code?.let {
    val predicate = `UserInfoHash $`.CODE.eq(code.uppercase())
    predicates.add(predicate)
}

firstName?.let {
    val predicate = `UserInfoHash$`.FIRST_NAME.containing(firstName.uppercase())
    predicates.add(predicate)
}

lastName?.let {
    val predicate = `UserInfoHash$`.LAST_NAME.containing(lastName.uppercase())
    predicates.add(predicate)
}

By adding the null checks and having the predicates be ignored if the params are null you can now do several chained filter commands where the params of the predicates could be null. This will AND the predicates. There is an or chaining method in Predicate that I haven't retrofitted to support this. So for now, only AND is supported.

Here's the PR https://github.com/redis/redis-om-spring/pull/251 - Once it's reviewed it should publish v0.8.3-SNAPSHOT

[lucasleon2107]

Hi @bsbodden, I tried sending null values in the latest version (0.8.4), but it's still not working

[bsbodden]

@lucasleon2107 can you modify the sample at https://github.com/redis-developer/redis-om-spring-kotlin-skeleton-app and add a reproducer. I'm working on adding a proper set of Kotlin specific tests to the redis-on repo.

[lucasleon2107]

Hi @bsbodden, can you please provide more specifics about what do you need me to add to the repo?

[bsbodden]

Hi @bsbodden, can you please provide more specifics about what do you need me to add to the repo?

Maybe a quick test on the main app https://github.com/redis-developer/redis-om-spring-kotlin-skeleton-app/blob/main/src/main/kotlin/com/redis/om/skeleton/OmKotlinSkeletonApplication.kt to show the failure, modify the models as needed. I'll then add it to the Kotlin set of tests I'm making.

[lucasleon2107]

Hi @bsbodden, I added a quick test on the main file. You can see that in this branch: https://github.com/lucasleon2107/redis-om-spring-kotlin-skeleton-app/tree/feature/test-null-filter-values

Also, I noticed that the generated Redis command for contains queries is: %%%{query}%%%. According to the docs, this performs a fuzzy match, and I'm getting unexpected results. It seems that the correct command should be: *{query}*