R2DBC SQL mapper conversion

Question

I have two tables in my use case..

1. Project
2. Task

A project can have multiple task associated with that project.

In task table I have FK relationship with project table, simple M:M relationship.

As in R2dbcRepository we do not have JPA support for table relationship , I am using join query with R2DBC DatabaseClient and executing the SQL query to get the data.

My SQL Query like this : select project.\"projectName\",project.\"projectId\",tsk.\"taskName\" \n" + "from evolutionlinkgroup.task as tsk \n" + "inner join evolutionlinkgroup.project on project.\"projectId\"=tsk.\"taskProjectId\"

After exciting this query I am mapping this into object :

client.sql(queryForAllProj) .map(mapper::apply) .all();

My Mapper Function :

public Project apply(Row row, Object o) {
    Integer taskId = row.get("taskId", Integer.class);
    String taskName = row.get("taskName", String.class);
    Integer projectId = row.get("projectId", Integer.class);
    String projectName = row.get("projectName", String.class);
    Task task = new Task(taskId,taskName,null);
    Project project = new Project(projectId, projectName,Arrays.asList(task));
    task.setProjectId(new Project(projectId, projectName,null));
    return project;
}

Which return me back Flux of project object : Flux<Project>

the mapper return me back data in this way, the same way my SQL fetch data from DB :

Project ID | Project Name | Task ID 

---

001 | Project1 | TSK001

001 | Project1 | TSK002

001 | Project1 | TSK003

002 | Project2 | TSK004

002 | Project2 | TSK006

003 | Project3 | TSK001

now from this Flux of project I want to convert it something like this.

Project ID | Project Name | Task ID 

---

001 | Project1 | ListOfTask(TSK001,TSK002,TSK003)

002 | Project2 | ListOfTask(TSK004,TSK006)

003 | Project3 | ListOfTask(TSK001)

Can any one suggest me how can I do that by doing something in the mapper function or after I receive the response from mapper again run some transformation on top of that data.

I tried in this way :

result.collect(
                Collectors.toMap(Project::getProjectId, Function.identity(), (Project project1, Project project2) -> {
                    project1.getTaskList().addAll(project2.getTaskList());
                    project2.getTaskList().clear();
                    return project1;
                })

But this is not what I am looking for. It returning me back map<key,project> , but I am not able convert that into Flux of project object along with the list of task object which are associated with that project.