从现有的微风中创建实体

我们正在后台处理这种事情。准备就绪时，我们会通知您。没有承诺或时间安排。

同时，我对此付诸行动。我决定利用微风EntityManager.exportEntities方法知道如何克隆实体这一事实。如果您阅读该方法的微妙源代码，就会知道它很棘手。

这是我想出的（作为平民，而不是Breeze开发人员）：

function cloneItem(item) {
    // export w/o metadata and then parse the exported string.
    var exported = JSON.parse(manager.exportEntities([item], false));
    // extract the entity from the export
    var type = item.entityType;
    var copy = exported.entityGroupMap[type.name].entities[0];
    // remove the entityAspect
    delete copy.entityAspect; 
    // remove the key properties
    type.keyProperties.forEach(function (p) { delete copy[p.name]; });

    // the "copy" provides the initial values for the create
    return manager.createEntity(type, copy);
}

像您一样，它保留外键属性，这意味着父源的引用导航属性将具有从缓存中提取的值（如果源具有此值）。

像您一样，将不会填充集合导航属性。此方法不知道如何克隆子代。这也不是不言自明的。这对您来说是额外的功劳。

2013年12月15日更新

正如您所问的那样，我已经实现了克隆孩子（集合导航）的功能。我遵循了您建议的语法，因此用法如下：

cloneItem(something, ['collectionProp1', 'collectionProp2']); 

请注意，我再次依靠Breeze导出来完成繁重的工作

警告：此代码非常脆弱，并且不能推广到所有型号

function cloneItem(item, collectionNames) {
    var manager = item.entityAspect.entityManager;
    // export w/o metadata and then parse the exported string.
    var exported = JSON.parse(manager.exportEntities([item], false));
    // extract the entity from the export
    var type = item.entityType;
    var copy = exported.entityGroupMap[type.name].entities[0];
    // remove the entityAspect (todo: remove complexAspect from nested complex types)
    delete copy.entityAspect;
    // remove the key properties (assumes key is store-generated)
    type.keyProperties.forEach(function (p) { delete copy[p.name]; });

    // the "copy" provides the initial values for the create
    var newItem = manager.createEntity(type, copy);

    if (collectionNames && collectionNames.length) {
        // can only handle parent w/ single PK values
        var parentKeyValue = newItem.entityAspect.getKey().values[0];
        collectionNames.forEach(copyChildren);
    }
    return newItem;

    function copyChildren(navPropName) {
        // todo: add much more error handling
        var navProp = type.getNavigationProperty(navPropName);
        if (navProp.isScalar) return; // only copies collection navigations. Todo: should it throw?

        // This method only copies children (dependent entities), not a related parent
        // Child (dependent) navigations have inverse FK names, not FK names
        var fk = navProp.invForeignKeyNames[0]; // can only handle child w/ single FK value
        if (!fk) return; 

        // Breeze `getProperty` gets values for all model libraries, e.g. both KO and Angular
        var children = item.getProperty(navPropName);
        if (children.length === 0) return;

        // Copy all children
        var childType = navProp.entityType;
        children = JSON.parse(manager.exportEntities(children, false));
        var copies = children.entityGroupMap[childType.name].entities;

        copies.forEach(function(c) {
            delete c.entityAspect;
            // remove key properties (assumes keys are store generated)
            childType.keyProperties.forEach(function (p) { delete c[p.name]; }); 
            // set the FK parent of the copy to the new item's PK               
            c[fk] = parentKeyValue;
            // merely creating them will cause Breeze to add them to the parent
            manager.createEntity(childType, c);
        });
    }