How/when to query 'extended' entities in B

Question

I have a ViewModel that loads up 'child' entities and I want to also display 'grandchild' entities based off of each child that is loaded. To simplify things, I need help identifying how to query these objects and display them under the proper 'tree' in the browser (apologies for my butchering of coding language : ))

I am using Knockout to bind the data and loading up the entities with Breeze. This question is an extension of When to add extend additional complex types onto a Breeze entity

Also - my model is EF code first and I have a configuration defining a one to many relationship between children and grandchildren, and I think Breeze knows this already but I am trying to figure out how to take advantage of this.

childs.js (view model)

var childs = ko.observableArray();
var grandChilds = ko.observableArray();
var parentId = ko.observable();

function refresh() {
    var parentId = (parent).parentId;  // << for ex. don't worry about this line : )
    return Q.all([getChildren(), getGrandChildren()]);
}

function getChildren() {
    return datacontext.getChildren(childs, parentId);
}

function getGrandChildren() {
    return datacontext.getGrandChildren(grandChilds);
}

and in the view (childs.html)

<div data-bind="foreach: childs">
    <div title="Go to Child Details">
        <div><strong data-bind="text: name"></strong></div>
        <div><strong data-bind="text: gender().description"></strong></div>
    </div>
    <div>
        <!-- ko.compose { view: grandChilds} --><!--/ko-->
    </div>
</div>

And my current datacontext for reference

    var getChilds= function (childsObservable, parentId) {

        var query = EntityQuery.from('Childs')
            .where('parentId', '==', parentId)
            .expand('grandChildren')
            .orderBy('id');

        return manager.executeQuery(query)
            .then(querySucceeded)
            .fail(queryFailed);

        function querySucceeded(data) {
            if (childsObservable) {
                childsObservable(data.results);
            }
            logger.log('Retrieved [Childs] and [Grandchilds] from remote data source', data, system.getModuleId(datacontext), true);
        }
    };

I want to load up only grandchildren of the children, and since there are many children I want to only display grandchildren under the correct child, not all grandchildren in one list. Any help would be appreciated.

Answer 1

You have three basic approaches to querying and "linking" related entities.

1) Use EntityQuery.expand

2) Use EntityAspect.loadNavigationProperty

3) Create a "broad" EntityQuery that just happens to encompass the entire graph and all of the parent/child relations will be automatically linked.