主从使用ContentResolver.applyBatch（）？

问题描述

我在想，如果可能的主页和详细记录保存到使用android.content.ContentResolver.applyBatch（）方法相同的操作内容提供商，其中的供应商参数随后ContentProviderOperation项目依赖于previous项目的结果。

I was wondering if its possible to save master and detail records to a content provider using the android.content.ContentResolver.applyBatch() method in the same operation where subsequent ContentProviderOperation items in the providers parameter depend on the result of previous items.

我遇到的问题是，实际的开放的我们不知道当时的ContentProviderOperation.newInsert（URI）方法被调用和URI是不可变的。

The problem I'm having is that the actual Uri isn't known at the time that the ContentProviderOperation.newInsert(Uri) method is called and the Uri is immutable.

我想出了如下所示：

What I have come up with is shown below:

主网址：内容：//com.foobar.masterdetail/master
详细网址：内容：//com.foobar.masterdetail/master/#/detail

Master Uri: content://com.foobar.masterdetail/master
Detail Uri: content://com.foobar.masterdetail/master/#/detail

ArrayList<ContentProviderOperation> operations = new ArrayList<ContentProviderOperation>();
operations.add(ContentProviderOperation.newInsert(intent.getData())
    .withValue(Master.NAME, "")
    .withValue(Master.VALUE, "")
    .build());
operations.add(ContentProviderOperation.newInsert(intent.getData()
        .buildUpon()
        .appendPath("#") /* ACTUAL VALUE NOT KNOWN UNTIL MASTER ROW IS SAVED */
        .appendPath("detail")
        .build())
    .withValue(Detail.MASTER_ID, /* WHAT GOES HERE? */)
    .withValue(Detail.NAME, "")
    .withValue(Detail.VALUE, "")
    .build());
ContentProviderResult[] results = this.getContentResolver().applyBatch(MasterDetail.AUTHORITY, operations);
for (ContentProviderResult result : results) {
    Uri test = result.uri;
}

在我的内容提供商，我重写了applyBatch（）方法，以包装在一个事务中的操作。

In my content provider, I am overriding the applyBatch() method in order to wrap the operation in a transaction.

这是可能的，或有没有更好的方式来做到这一点？

Is this possible or is there a better way to do this?

感谢。

推荐答案

从操作阵列是由它在数组中的索引标识项目产生的每个结果。随后的操作可以通过withValueBackReference（）方法引用这些结果。

Each result produced from an item in the operations array is identified by its index in the array.Subsequent operations may reference those results via the withValueBackReference() method.

.withValue(Detail.MASTER_ID, /* WHAT GOES HERE? */)

变为

.withValueBackReference(Detail.MASTER_ID, 0)

这种用法的一个完整的例子可以在sample的ContactManager 的。的0是从其中获得的值ContentProviderOperation的索引

A complete example of this usage can be found in sample ContactManager.The 0 is the index of the ContentProviderOperation from which the value is obtained.

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