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顺序管道块

`SequentialPipelineBlocks` 是一种多块类型，它将其他 `ModularPipelineBlocks` 按顺序组合在一起。数据通过 `intermediate_inputs` 和 `intermediate_outputs` 线性地从一个块流向下一个块。`SequentialPipelineBlocks` 中的每个块通常代表管道中的一个步骤，通过组合它们，您逐步构建一个管道。

本指南向您展示如何将两个块连接成一个 `SequentialPipelineBlocks`。

创建两个 `ModularPipelineBlocks`。第一个块 `InputBlock` 输出一个 `batch_size` 值，第二个块 `ImageEncoderBlock` 使用 `batch_size` 作为 `intermediate_inputs`。

InputBlock
ImageEncoderBlock

    from diffusers.modular_pipelines import ModularPipelineBlocks, InputParam, OutputParam

    class InputBlock(ModularPipelineBlocks):

        @property
        def inputs(self):
            return [
                InputParam(name="prompt", type_hint=list, description="list of text prompts"),
                InputParam(name="num_images_per_prompt", type_hint=int, description="number of images per prompt"),
            ]

        @property
        def intermediate_outputs(self):
            return [
                OutputParam(name="batch_size", description="calculated batch size"),
            ]

        @property
        def description(self):
            return "A block that determines batch_size based on the number of prompts and num_images_per_prompt argument."

        def __call__(self, components, state):
            block_state = self.get_block_state(state)
            batch_size = len(block_state.prompt)
            block_state.batch_size = batch_size * block_state.num_images_per_prompt
            self.set_block_state(state, block_state)
            return components, state

通过定义一个`InsertableDict`来连接两个块，将块名称映射到块实例。块按照它们在`blocks_dict`中注册的顺序执行。

使用`from_blocks_dict()`来创建一个`SequentialPipelineBlocks`。

    from diffusers.modular_pipelines import SequentialPipelineBlocks, InsertableDict

    blocks_dict = InsertableDict()
    blocks_dict["input"] = input_block
    blocks_dict["image_encoder"] = image_encoder_block

    blocks = SequentialPipelineBlocks.from_blocks_dict(blocks_dict)

通过调用`blocks`来检查`SequentialPipelineBlocks`中的子块，要获取更多关于输入和输出的详细信息，可以访问`docs`属性。

    print(blocks)
    print(blocks.doc)

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