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[Full documentation index](<https://docs.dhtmlx.com/planning-engine/llms.txt>)


# AssignmentData

Books a resource on a task at a utilization rate. An optional slice limits the booking to part of the task's work. Add instances to [`ProjectData.assignments`](<https://docs.dhtmlx.com/planning-engine/java/api/data/project-data.md>). Create one with `new AssignmentData()` and the fluent setters. Assignments added after the first solve go through [`SchedulingChanges.assignments`](<https://docs.dhtmlx.com/planning-engine/java/api/changes/scheduling-changes.md>), and edits go through [`AssignmentUpdate`](<https://docs.dhtmlx.com/planning-engine/java/api/changes/assignment-update.md>).

## Declaration

```java
public class AssignmentData extends ValueRecord implements DeepCloneable<AssignmentData>
```

## Constructors

### AssignmentData()

```java
public AssignmentData()
```

Creates an assignment with every field at its default. Set `task`, `resource` and `value` before the data reaches the engine.

## Fields

| Field | Type | Default | Description |
|---|---|---|---|
| `id` | [`Id`](<https://docs.dhtmlx.com/planning-engine/java/api/data/id.md>) | `null` | Assignment ID. `null` gets a generated string ID (`"$generated_assignment_1"`, `"$generated_assignment_2"`, ...) on import. A generated ID never takes an ID already used by another assignment. |
| `task` | [`Id`](<https://docs.dhtmlx.com/planning-engine/java/api/data/id.md>) | `null` | ID of the assigned task. Required: `null` throws `NullPointerException` on import. |
| `resource` | [`Id`](<https://docs.dhtmlx.com/planning-engine/java/api/data/id.md>) | `null` | ID of the booked resource. Required: `null` throws `NullPointerException` on import. |
| `value` | `double` | `0.0` | Utilization rate, in the units of [`ResourceData.capacity`](<https://docs.dhtmlx.com/planning-engine/java/api/data/resource-data.md>): `1.0` = 100 %. Must be finite and greater than 0, so the default `0.0` is rejected. |
| `offset` | `Double` | `null` | Start of the slice: worked time from the task start, in the task's `durationUnit`. `null` means `0`. |
| `duration` | `Double` | `null` | Length of the slice: worked time booked from `offset`, in the task's `durationUnit`. `null` books up to the task end. |

### Slices

`offset` and `duration` choose which part of the task's work the assignment books. They change resource load only. Task dates never depend on them. Both are measured in worked time on the assignment's calendar, so non-working time and pauses don't count. The slice is clipped to the task's work when load is booked, so it follows a task that gets shorter later. An `offset` at or past the task's work books nothing. Several assignments of one resource on one task each book their own slice at their own `value`, and overlapping slices add up.

How the assignment's calendar is picked is covered in [Working time and calendars](<https://docs.dhtmlx.com/planning-engine/java/scheduling/working-time-calendars.md>). For a walk-through, see [Split assignment work](<https://docs.dhtmlx.com/planning-engine/java/how-to/split-assignment-work.md>).

### Assignments on unscheduled tasks

An assignment whose task has [`TaskData.unscheduled`](<https://docs.dhtmlx.com/planning-engine/java/api/data/task-data.md>) set to `true` is still validated, but it books no load. The result reports it in `notes` as a [`Note.DroppedAssignment`](<https://docs.dhtmlx.com/planning-engine/java/api/results/note.md>). The assignment keeps its slice and books it again when the task is scheduled.

## Methods

### withId

```java
public AssignmentData withId(Id value)
```

Sets `id` and returns this instance for chaining.

**Returns** - this `AssignmentData`.

### withTask

```java
public AssignmentData withTask(Id value)
```

Sets `task` and returns this instance for chaining.

**Returns** - this `AssignmentData`.

### withResource

```java
public AssignmentData withResource(Id value)
```

Sets `resource` and returns this instance for chaining.

**Returns** - this `AssignmentData`.

### withValue

```java
public AssignmentData withValue(double value)
```

Sets `value` and returns this instance for chaining.

**Returns** - this `AssignmentData`.

### withOffset

```java
public AssignmentData withOffset(Double value)
```

Sets `offset` and returns this instance for chaining. `null` clears it.

**Returns** - this `AssignmentData`.

### withDuration

```java
public AssignmentData withDuration(Double value)
```

Sets `duration` and returns this instance for chaining. `null` clears it.

**Returns** - this `AssignmentData`.

### deepClone

```java
public AssignmentData deepClone()
```

Returns a copy with the same field values. Every field is immutable (`Id`) or a value, so the copy is fully independent.

**Returns** - a new `AssignmentData`.

### copy

```java
public AssignmentData copy()
```

Returns a shallow copy. For `AssignmentData` it is equivalent to `deepClone()`.

**Returns** - a new `AssignmentData` with the same field values.

### equals, hashCode, toString

```java
public boolean equals(Object other)
public int hashCode()
public String toString()
```

Inherited from [`ValueRecord`](<https://docs.dhtmlx.com/planning-engine/java/api/support/value-record.md>). Two `AssignmentData` are equal when all six fields are equal. `toString()` lists the fields, for logging.

## Errors

The call that receives the data throws [`InputException`](<https://docs.dhtmlx.com/planning-engine/java/api/errors/input-exception.md>) with kind [`InputErrorKind.VALIDATION`](<https://docs.dhtmlx.com/planning-engine/java/api/errors/input-exception.md#inputerrorkind>):

| Path | When |
|---|---|
| `assignments[i].id` | Two assignments share an ID. IDs compare by their key, so `Id.num(1)` and `Id.str("1")` collide. |
| `assignments[i].value` | `value` is not finite or is `<= 0`. |
| `assignments[i].offset` | `offset` is not finite or is `< 0`. |
| `assignments[i].duration` | `duration` is not finite or is `<= 0`. |
| `assignments[i].resource` | No resource has this ID. |
| `assignments[i].task` | No task has this ID. |
| `assignments[i]` | In [`CalendarMode.RESOURCE`](<https://docs.dhtmlx.com/planning-engine/java/api/data/calendar-mode.md>), the task has its own calendar, the resource has a calendar, and the two share no weekly working time. |
| `id` | An `id`, `task` or `resource` holds a number that isn't finite. |

In [`Validation.REPAIR`](<https://docs.dhtmlx.com/planning-engine/java/api/project/validation.md>) mode some of these are fixed instead, and each fix is recorded as a [`Note.Repaired`](<https://docs.dhtmlx.com/planning-engine/java/api/results/note.md>):

- An invalid `offset` or `duration` is cleared to `null`.
- With a repeated non-null `id`, the later assignment replaces the earlier one at the earlier position.

## Example

```java
import java.util.List;
import org.dhtmlx.plen.*;

public class AssignmentDataExample {
  public static void main(String[] args) throws Exception {
    ProjectData data = new ProjectData()
        .withTasks(List.of(
            new TaskData(Id.num(1))
                .withStartDate(Moment.fromYmdHm(2026, 3, 2, 8, 0))
                .withDuration(5.0)))
        .withResources(List.of(new ResourceData().withId(Id.str("ann"))))
        .withAssignments(List.of(
            // Full time for the whole task.
            new AssignmentData()
                .withTask(Id.num(1))
                .withResource(Id.str("ann"))
                .withValue(1.0),
            // Half time on the last day only: days 4 to 5 of the task's work.
            new AssignmentData()
                .withId(Id.str("review"))
                .withTask(Id.num(1))
                .withResource(Id.str("ann"))
                .withValue(0.5)
                .withOffset(4.0)
                .withDuration(1.0)));

    ScheduleResult result = new Project().solve(data, new SolveOptions());
    System.out.println(result.overallocations);
  }
}
```

## Related

- [`ResourceData`](<https://docs.dhtmlx.com/planning-engine/java/api/data/resource-data.md>) - the resource it books
- [`TaskData`](<https://docs.dhtmlx.com/planning-engine/java/api/data/task-data.md>) - the task it is booked on
- [`AssignmentUpdate`](<https://docs.dhtmlx.com/planning-engine/java/api/changes/assignment-update.md>) - editing an assignment in a live project
- [Resources and assignments](<https://docs.dhtmlx.com/planning-engine/java/resources-and-assignment/resources-and-assignments.md#assignments>) - assignments, slices and overallocation
- [Split assignment work](<https://docs.dhtmlx.com/planning-engine/java/how-to/split-assignment-work.md>) - booking a slice of a task's work