Key Features

1. Model-agnostic GrevGanttMixin — inherit it on any models.Model subclass to get the get_grev_gantt_data() RPC endpoint and all server-side scheduling helpers.
2. Typed dependency links — grev.gantt.link stores Finish-to-Start, Start-to-Start, Finish-to-Finish, and Start-to-Finish links between records of any Gantt-enabled model.
3. Baseline snapshots — grev.gantt.baseline stores named planned-start / planned-end snapshots for any record, overlaid as dashed bars on the chart.
4. Critical path highlighting — computed in the OWL renderer from the dependency graph.
5. Auto-scheduler — drag a bar; successors cascade automatically via web_grev_gantt_reschedule() and _cascade_reschedule().
6. S-curve analytics — cumulative planned vs actual progress overlaid on the timeline.
7. Resource histogram — capacity load per assignee or work centre.
8. Undo / redo — full undo stack backed by action_rollback_grev_gantt_scheduling().
9. Export — export the Gantt chart view to PNG or PDF.

Architecture

Adding Gantt to a Custom Model

To add a Gantt chart to any existing model:

class MyModel(models.Model):
    _name = 'my.model'
    _inherit = ['my.model', 'grev.gantt.mixin']

    _grev_gantt_start_name = 'date_start'   # field containing bar start
    _grev_gantt_stop_name  = 'date_end'     # field containing bar end

Then add a grev_gantt arch to a view record:

<record id="view_my_model_grev_gantt" model="ir.ui.view">
  <field name="name">my.model.grev_gantt</field>
  <field name="model">my.model</field>
  <field name="arch" type="xml">
    <grev_gantt
        date_start="date_start"
        date_stop="date_end"
        progress="progress_field"
        default_scale="week"
        snap_at="1d"
        show_critical_path="1">
      <field name="project_id"/>
    </grev_gantt>
  </field>
</record>

Arch Attributes Reference

Overridable Hooks

Override these methods in your concrete model to integrate real capacity data:

def _grev_gantt_progress_bar(self, field, res_ids, start_date, stop_date):
    """Return {res_id: {'value': float, 'max_value': float}}."""
    ...

def _grev_gantt_unavailability(self, field, res_ids, start_date, stop_date, scale):
    """Return {res_id: [{'start': datetime_str, 'stop': datetime_str}]}."""
    ...

Creating Dependency Links

Dependency links can be created in two ways:

1. Via the task form — if your model defines source_ids / target_ids Many2many fields, changes are automatically mirrored to grev.gantt.link by the mixin's write() override.
2. Directly on grev.gantt.link — go to :menuselection:`Technical --> Gantt --> Dependency Links` and create a link manually using the Source Record and Target Record Reference fields.

Creating Baseline Snapshots

Go to :menuselection:`Technical --> Gantt --> Baseline Snapshots` and create a baseline for any Gantt-enabled record. Baselines appear as dashed overlay bars on the chart when :guilabel:`Show Baselines` is toggled on in the Gantt toolbar.

Rescheduling Tasks

Drag any bar left or right on the Gantt chart. The module calls web_grev_gantt_reschedule() on the server, which:

1. Updates the dragged record's start and stop dates.
2. Computes the shift delta.
3. Cascades the same delta to all successor records (depth-first).
4. Returns old values so the undo action can roll back the change.

To undo, click :guilabel:`Undo` in the Gantt toolbar.

grev.gantt.mixin

Abstract model that all Gantt-enabled models inherit.

grev.gantt.link

Model-agnostic typed dependency link between any two Gantt-enabled records.

grev.gantt.baseline

Planned-date snapshot for any Gantt-enabled record.