变量中Zero Padding优化咨询：替代循环迭代的更优实现方法

• 输入值=1234，Input Range=2，预期输出=1200
• 输入值=12345，Input Range=3，预期输出=12000
• 需求：将输入值右侧对应Input Range数量的数字替换为零

{    
    "name": "RoundPad",    
    "properties": {        
        "activities": [            
            {                
                "name": "ForEach1",                
                "type": "ForEach",                
                "dependsOn": [],                
                "userProperties": [],                
                "typeProperties": {                    
                    "items": {                        
                        "value": "@range(1,pipeline().parameters.Range)",                        
                        "type": "Expression"                    
                    },                    
                    "isSequential": true,                    
                    "activities": [                        
                        {                            
                            "name": "Set variable1",                            
                            "type": "SetVariable",                            
                            "dependsOn": [],                            
                            "userProperties": [],                            
                            "typeProperties": {                                
                                "variableName": "TempPower",                                
                                "value": {                                    
                                    "value": "@string(mul(int(variables('Power')),10))",                                    
                                    "type": "Expression"                                
                                }                            
                            }                        
                        },                        
                        {                            
                            "name": "Set variable2",                            
                            "type": "SetVariable",                            
                            "dependsOn": [                                
                                {                                    
                                    "activity": "Set variable1",                                    
                                    "dependencyConditions": [                                        
                                        "Succeeded"                                    
                                    ]                                
                                }                            
                            ],                            
                            "userProperties": [],                            
                            "typeProperties": {                                
                                "variableName": "Power",                                
                                "value": {                                    
                                    "value": "@variables('TempPower')",                                    
                                    "type": "Expression"                                
                                }                            
                            }                        
                        }                    
                    ]                
                }            
            },            
            {                
                "name": "Set variable3",                
                "type": "SetVariable",                
                "dependsOn": [                    
                    {                        
                        "activity": "ForEach1",                        
                        "dependencyConditions": [                            
                            "Succeeded"                        
                        ]                    
                    }                
                ],                
                "userProperties": [],                
                "typeProperties": {                    
                    "variableName": "Output",                    
                    "value": {                        
                        "value": "@string(mul(div(int(pipeline().parameters.Input),int(variables('Power') )),int(variables('Power'))))",                        
                        "type": "Expression"                    
                    }                
                }            
            }        
        ],        
        "parameters": {            
            "Input": {                
                "type": "string",                
                "defaultValue": "1234"            
            },            
            "Range": {                
                "type": "int",                
                "defaultValue": 2            
            }        
        },        
        "variables": {            
            "TempPower": {                
                "type": "String",                
                "defaultValue": "1"            
            },            
            "Output": {                
                "type": "String"            
            },            
            "Power": {                
                "type": "String",                
                "defaultValue": "1"            
            }        
        },        
        "annotations": []    
    }
}

是否存在无需借助ForEach迭代和多变量的更优实现方法？

当然有更简洁的实现方式，完全不需要ForEach迭代和多变量。利用Azure Data Factory的内置表达式就能一步完成需求：

1. 用power(10, pipeline().parameters.Range)直接计算出对应位数的10次幂（比如Range=2时得到100，Range=3时得到1000）
2. 对输入值执行「整除该幂次后再乘以该幂次」的操作，就能自动将右侧对应位数的数字置零
3. 最后把结果转为字符串即可

对应的表达式如下：

@string(mul(div(int(pipeline().parameters.Input), power(10, pipeline().parameters.Range)), power(10, pipeline().parameters.Range)))

简化后的Pipeline只需要保留一个SetVariable活动和Output变量，具体结构如下：

{
    "name": "RoundPad",
    "properties": {
        "activities": [
            {
                "name": "Set Output",
                "type": "SetVariable",
                "dependsOn": [],
                "userProperties": [],
                "typeProperties": {
                    "variableName": "Output",
                    "value": {
                        "value": "@string(mul(div(int(pipeline().parameters.Input), power(10, pipeline().parameters.Range)), power(10, pipeline().parameters.Range)))",
                        "type": "Expression"
                    }
                }
            }
        ],
        "parameters": {
            "Input": {
                "type": "string",
                "defaultValue": "1234"
            },
            "Range": {
                "type": "int",
                "defaultValue": 2
            }
        },
        "variables": {
            "Output": {
                "type": "String"
            }
        },
        "annotations": []
    }
}

这种方式代码更简洁，执行效率也更高，省去了循环迭代的额外开销。

内容的提问来源于stack exchange，提问作者Nandan