You can now assign task successor and predecessors. Sweet. Thanks myoualid!

src/blenderbim/blenderbim/bim/module/sequence/__init__.py

@@ -32,6 +32,10 @@ classes = (
     operator.EnableEditingTask,
     operator.DisableEditingTask,
     operator.EditTask,
+    operator.AssignPredecessor,
+    operator.AssignSuccessor,
+    operator.UnassignPredecessor,
+    operator.UnassignSuccessor,
     prop.WorkPlan,
     prop.BIMWorkPlanProperties,
     prop.Task,

src/blenderbim/blenderbim/bim/module/sequence/operator.py

@@ -546,3 +546,75 @@ class EditTask(bpy.types.Operator):
         bpy.ops.bim.disable_editing_task()
         bpy.ops.bim.enable_editing_tasks(work_schedule=props.active_work_schedule_id)
         return {"FINISHED"}
+
+
+class AssignPredecessor(bpy.types.Operator):
+    bl_idname = "bim.assign_predecessor"
+    bl_label = "Assign Predecessor"
+    task: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.BIMWorkScheduleProperties
+        self.file = IfcStore.get_file()
+        ifcopenshell.api.run(
+            "sequence.assign_sequence",
+            self.file,
+            relating_process=IfcStore.get_file().by_id(self.task),
+            related_process=IfcStore.get_file().by_id(props.active_task_id),
+        )
+        Data.load(self.file)
+        return {"FINISHED"}
+
+
+class AssignSuccessor(bpy.types.Operator):
+    bl_idname = "bim.assign_successor"
+    bl_label = "Assign Successor"
+    task: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.BIMWorkScheduleProperties
+        self.file = IfcStore.get_file()
+        ifcopenshell.api.run(
+            "sequence.assign_sequence",
+            self.file,
+            relating_process=IfcStore.get_file().by_id(props.active_task_id),
+            related_process=IfcStore.get_file().by_id(self.task),
+        )
+        Data.load(self.file)
+        return {"FINISHED"}
+
+
+class UnassignPredecessor(bpy.types.Operator):
+    bl_idname = "bim.unassign_predecessor"
+    bl_label = "Unassign Predecessor"
+    task: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.BIMWorkScheduleProperties
+        self.file = IfcStore.get_file()
+        ifcopenshell.api.run(
+            "sequence.unassign_sequence",
+            self.file,
+            relating_process=IfcStore.get_file().by_id(self.task),
+            related_process=IfcStore.get_file().by_id(props.active_task_id),
+        )
+        Data.load(self.file)
+        return {"FINISHED"}
+
+
+class UnassignSuccessor(bpy.types.Operator):
+    bl_idname = "bim.unassign_successor"
+    bl_label = "Unassign Successor"
+    task: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.BIMWorkScheduleProperties
+        self.file = IfcStore.get_file()
+        ifcopenshell.api.run(
+            "sequence.unassign_sequence",
+            self.file,
+            relating_process=IfcStore.get_file().by_id(props.active_task_id),
+            related_process=IfcStore.get_file().by_id(self.task),
+        )
+        Data.load(self.file)
+        return {"FINISHED"}

src/blenderbim/blenderbim/bim/module/sequence/ui.py

@@ -153,6 +153,7 @@ class BIM_PT_work_schedules(Panel):
 class BIM_UL_tasks(UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
         if item:
+            props = context.scene.BIMWorkScheduleProperties
             row = layout.row(align=True)
             for i in range(0, item.level_index):
                 row.label(text="", icon="BLANK1")
@@ -169,10 +170,20 @@ class BIM_UL_tasks(UIList):
                 row.label(text="", icon="DOT")
             row.prop(item, "identification", emboss=False, text="")
             row.prop(item, "name", emboss=False, text="")
-            if context.scene.BIMWorkScheduleProperties.active_task_id == item.ifc_definition_id:
+            if props.active_task_id == item.ifc_definition_id:
                 row.operator("bim.edit_task", text="", icon="CHECKMARK")
                 row.operator("bim.disable_editing_task", text="", icon="CANCEL")
-            if context.scene.BIMWorkScheduleProperties.active_task_id:
+            elif props.active_task_id:
+                if props.active_task_id in Data.tasks[item.ifc_definition_id]["IsPredecessorTo"]:
+                    row.operator("bim.unassign_predecessor", text="", icon="BACK", emboss=False).task = item.ifc_definition_id
+                else:
+                    row.operator("bim.assign_predecessor", text="", icon="TRACKING_BACKWARDS", emboss=False).task = item.ifc_definition_id
+
+                if props.active_task_id in Data.tasks[item.ifc_definition_id]["IsSuccessorFrom"]:
+                    row.operator("bim.unassign_successor", text="", icon="FORWARD", emboss=False).task = item.ifc_definition_id
+                else:
+                    row.operator("bim.assign_successor", text="", icon="TRACKING_FORWARDS", emboss=False).task = item.ifc_definition_id
+
                 row.operator("bim.add_task", text="", icon="ADD").task = item.ifc_definition_id
                 row.operator("bim.remove_task", text="", icon="X").task = item.ifc_definition_id
             else:

src/ifcopenshell-python/ifcopenshell/api/sequence/assign_sequence.py

@@ -0,0 +1,27 @@
+import ifcopenshell
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {
+            "relating_process": None,
+            "related_process": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for rel in self.settings["related_process"].IsSuccessorFrom or []:
+            if rel.RelatingProcess == self.settings["relating_process"]:
+                return rel
+        return self.file.create_entity(
+            "IfcRelSequence",
+            **{
+                "GlobalId": ifcopenshell.guid.new(),
+                "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
+                "RelatingProcess": self.settings["relating_process"],
+                "RelatedProcess": self.settings["related_process"],
+            }
+        )

src/ifcopenshell-python/ifcopenshell/api/sequence/assign_task_predecessor.py

@@ -1,25 +0,0 @@
-import ifcopenshell
-import ifcopenshell.api
-
-
-class Usecase:
-    def __init__(self, file, **settings):
-        self.file = file
-        self.settings = {
-            "predecessor_task": None,
-            "sequence_type":"FINISH_START",
-            "task": None,            
-        }
-        for key, value in settings.items():
-            self.settings[key] = value
-
-    def execute(self):
-        #TODO: tasks can only have one relationship between oneanother: if a relationship is already assigned, it should overide the previous one's settings.
-        rel_sequence = self.file.create_entity("IfcRelSequence",**{
-                "GlobalId": ifcopenshell.guid.new(),
-                "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
-                "RelatingProcess": self.settings["predecessor_task"],
-                "SequenceType": self.settings["sequence_type"],
-                "RelatedProcess": self.settings["task"],
-            })
-        return rel_sequence

src/ifcopenshell-python/ifcopenshell/api/sequence/assign_task_successor.py

@@ -1,25 +0,0 @@
-import ifcopenshell
-import ifcopenshell.api
-
-
-class Usecase:
-    def __init__(self, file, **settings):
-        self.file = file
-        self.settings = {
-            "task": None,
-            "sequence_type":"FINISH_START",
-            "successor_task": None,
-        }
-        for key, value in settings.items():
-            self.settings[key] = value
-
-    def execute(self):
-        #TODO: tasks can only have one relationship between oneanother: if a relationship is already assigned, it should overide the previous one's settings.
-        rel_sequence = self.file.create_entity("IfcRelSequence",**{
-                "GlobalId": ifcopenshell.guid.new(),
-                "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
-                "RelatingProcess": self.settings["task"],
-                "SequenceType": self.settings["sequence_type"],
-                "RelatedProcess": self.settings["successor_task"],
-            })
-        return rel_sequence

src/ifcopenshell-python/ifcopenshell/api/sequence/data.py

@@ -76,6 +76,10 @@ class Data:
             data = task.get_info()
             del data["OwnerHistory"]
             data["RelatedObjects"] = []
+            data["IsPredecessorTo"] = []
+            data["IsSuccessorFrom"] = []
             for rel in task.IsNestedBy:
                 [data["RelatedObjects"].append(o.id()) for o in rel.RelatedObjects if o.is_a("IfcTask")]
+            [data["IsPredecessorTo"].append(rel.RelatedProcess.id()) for rel in task.IsPredecessorTo or []]
+            [data["IsSuccessorFrom"].append(rel.RelatingProcess.id()) for rel in task.IsSuccessorFrom or []]
             cls.tasks[task.id()] = data

src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_sequence.py

@@ -0,0 +1,18 @@
+import ifcopenshell
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {
+            "relating_process": None,
+            "related_process": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for rel in self.settings["related_process"].IsSuccessorFrom or []:
+            if rel.RelatingProcess == self.settings["relating_process"]:
+                self.file.remove(rel)