Breeze bug? It's trying to add related entity even though only the primary entity is specified in savechanges()

Question

Widgetmaster has many widgetVersions. A widgetVersion can only have one widgetMaster.

Public Class widgetMaster
    Public Property ID() As Integer

    ...other properties

    Public Overridable Property WidgetVersions() As ICollection(Of widgetVersion)
End Class

Public Class widgetVersion
    Public Property ID() As Integer
    Public Property WidgetMasterID() As Integer

    ...other properties

    Public Overridable Property WidgetMaster() As widgetMaster
End Class

My viewmodel:

    var newWidget = ko.observable();
    var newWidgetVersion = ko.observable();
    var isSaving = ko.observable(false);

    var activate = function () {
        return datacontext.newWidget(newWidget),
               datacontext.newWidgetVersion(newWidgetVersion).then(setNewWidgetVariables());
        }
    };

    var setNewWidgetVariables = function() {
        newWidget().groupId(globalVar.selectedGroupId());
    }


    var save = function () {
        isSaving(true);
        return datacontext.saveChanges([newWidget]).fin(complete);

        function complete() {
            isSaving(false);
        }
    };

Even though my saveChanges specifies only the newWidget entity:

return datacontext.saveChanges([newWidget]).fin(complete);

...Breeze is still adding in a child "widgetVersion" to the widgetVersions table (without any widgetMasterID set either - it's set to 0) and I don't want it to do that! Or at least if it persists, I want it to pick up the newly-added widgetMasterID.

Why does Breeze add the related entity even though I've told it to only do the master? I want to do the master, fetch the new ID, then save the widgetVersion entity with that new ID included and Breeze is stopping me doing this for some reason I don't understand.

Hang on. (Where's Ward when you need him, eh) Am I doing this wrong? Should I just be creating a newWidget entity via createEntity('widgetMaster') and then doing something like attaching the widgetVersion entity to it? Would that create the link that would automatically fill in the widgetMaster ID in the related widgetVersion entity? — TheMook
If widgetChild is a new entity that is added to widgetParent then Breeze and your database cannot add only the parent, they must add any children that are required for the database to not throw any null reference errors. — PW Kad
But it's not added to the parent. Not explicitly anyway. As you can see in my activate method I create two observables that contain entities. One contains widgetMaster and another contains a widgetVersion. The problem appears to be that even though I explicitly tell the datacontext to save just the widgetMaster to start with, it also goes off and creates the widgetVersion I have in cache. What's the point in allowing Breeze to specify the entity to save if it's just going to ignore that parameter? — TheMook

TheMook TheMook · Accepted Answer · 2013-09-24T17:57:51

OK then. Sorry, my fault for not thinking it through. My datacontext.savechanges was an exposed function from the module and not a direct call to the manager. Furthermore the exposed function didn't accept the entity parameter so even though I was setting it, it wasn't getting through to the actual manager.saveChanges method.

On top of that I was setting the entity to the observable and not the value of the observable, so if you're reading this in months to come, make sure you add those parentheses at the end of your observable kiddies!

    var save = function () {
        var saveArray = new Array();
        saveArray[0] = newWidgetMaster();
        isSaving(true);

        return datacontext.saveChanges(saveArray).fin(complete);

        function complete() {
            isSaving(false);
        }
    };

Edited to add:

Just for completeness and to help noobs like I was (still am!) here's the datacontext amd module's savechanges method (credit to John Papa for this, but next time include the entity (at least) as a parameter you ratbag!)

    var saveChanges = function (entities) {
        return manager.saveChanges(entities)
            .then(saveSucceeded)
            .fail(saveFailed);

        function saveSucceeded(saveResult) {
            log('Saved data successfully', saveResult, true);
        }

        function saveFailed(error) {
            var msg = 'Save failed: ' + getErrorMessages(error);
            logError(msg, error);
            error.message = msg;
            throw error;
        }
    };

Breeze bug? It's trying to add related entity even though only the primary entity is specified in savechanges()

1 Answers