Query related Tasks does not work

Question

I need to query all related tasks from a contact (currentRecordId) but my code below shows nothing. What I'm doing wrong?

Map<Id, TaskRelation> relatedTasks1 = new Map<Id, TaskRelation>([select taskId from TaskRelation where relationId = :currentRecordId]); 
system.debug('size relatedtasks1 ' +relatedtasks1.size()); // 3 items
List<Task> listtasks = [select Id, Subject, CreatedDate, Createdby.Name, Owner.Name, RecordType.Name, Status, Who.Name, Who.Id, What.Name from Task where Id IN :relatedTasks1.keySet()];
system.debug('size listtasks ' +listtasks.size()); // 0 items
for(Task a : listtasks) { 
    wrapperList.add(new Wrapper(a, 'Task'));
}

DEBUG of map relatedtasks1

09:36:49:197 VARIABLE_ASSIGNMENT [23]|relatedTasks1|{"0RT1x0000094HFHGA2":{"TaskId":"00T1x00000CSmgFEAT","Id":"0RT1x0000094HFHGA2"},"0RT1x0000094HEeGAM":{"TaskId":"00T1x00000CSmdSEAT","Id":"0RT1x0000094HEeGAM"},"0RT1x0000094HF8GAM":{"TaskId":"00T1x00000CSmgAEAT","Id":"0RT1x0000094HF8GAM"}}|0x3964be86

Debug of list Listtasks

09:36:49:199 SOQL_EXECUTE_BEGIN [24]|Aggregations:0|SELECT Id, Subject, CreatedDate, Createdby.Name, Owner.Name, RecordType.Name, Status, Who.Name, Who.Id, What.Name FROM Task WHERE Id = :tmpVar1 09:36:49:206 SOQL_EXECUTE_EXPLAIN [24]|Index on Task : [Id], cardinality: 3, sobjectCardinality: 29, relativeCost 0.333

Answer 1

the problem is with Map<Id, TaskRelation> relatedTasks1 = new Map<Id, TaskRelation>([select taskId from TaskRelation where relationId = :currentRecordId]);

when you are passing into the constructor of the Map a list of sobjects, the key is set to record id. In this example, it is TaskRelation.Id

In the next line List<Task> listtasks = [select Id, Subject, CreatedDate, Createdby.Name, Owner.Name, RecordType.Name, Status, Who.Name, Who.Id, What.Name from Task where Id IN :relatedTasks1.keySet()]; Task records are filtered by Task.Id, but key set returns TaskRelation.Id set. So even not proper sobject ids are used. Sрould be ids of Task, but сгккутедн ids of TaskRelation.

There is one step that is missing. Getting from relatedTasks1 TaskId field values. Your code should look like this:

Map<Id, TaskRelation> relatedTasks1 = new Map<Id, TaskRelation>([select taskId from TaskRelation where relationId = :currentRecordId]);

Set<Id> taskIdsSet = new Set<Id>();
for(TaskRelation relation: relatedTasks1.values()){
    taskIdsSet.add(relation.TaskId);
}


List<Task> listtasks = [select Id, Subject, CreatedDate, Createdby.Name, Owner.Name, RecordType.Name, Status, Who.Name, Who.Id, What.Name from Task where Id IN :taskIdsSet];

---

Moreover, it is possible to do it in one query using a nested query:

List<Task> tasks= [
    SELECT Id, Subject
    FROM Task
    WHERE Id IN (
        SELECT TaskId
        FROM TaskRelation
        where RelationId = :currentRecordId
    )
];

---

Or you can query needed info also using a parent relationship:

List<TaskRelation> relations= [
    SELECT Id, Task.Subject, Task.Owner.Name
    FROM TaskRelation
    WHERE RelationId = :currentRecordId
];