要按照嵌套对象的数量筛选文档，可以使用递归函数来遍历文档中的每个对象，并计算嵌套对象的数量。

以下是一个示例代码，用于按照嵌套对象的数量筛选文档，该代码使用Python的json库来解析JSON文档：

import json

def count_nested_objects(obj):
    count = 0
    if isinstance(obj, dict):
        for key, value in obj.items():
            if isinstance(value, (dict, list)):
                count += 1 + count_nested_objects(value)
    elif isinstance(obj, list):
        for item in obj:
            if isinstance(item, (dict, list)):
                count += 1 + count_nested_objects(item)
    return count

def filter_documents(docs, min_nested_objects, max_nested_objects):
    filtered_docs = []
    for doc in docs:
        obj = json.loads(doc)  # 解析JSON文档
        nested_objects = count_nested_objects(obj)
        if min_nested_objects <= nested_objects <= max_nested_objects:
            filtered_docs.append(doc)
    return filtered_docs

# 示例用法
documents = [
    '{"name": "Document 1", "data": {"nested_obj": {"nested_obj2": {}}}}',
    '{"name": "Document 2", "data": {"nested_obj": [{"nested_obj2": {}}, {"nested_obj3": {}}]}}',
    '{"name": "Document 3", "data": {"nested_obj": {"nested_obj2": {}, "nested_obj3": {}}}}',
    '{"name": "Document 4", "data": {}}'
]

filtered_documents = filter_documents(documents, 1, 2)
for doc in filtered_documents:
    print(doc)

在上面的示例中，count_nested_objects函数用于计算嵌套对象的数量，filter_documents函数用于筛选满足条件的文档。你可以根据自己的需求调整这两个函数的逻辑，以适应不同的数据结构和筛选条件。