简化长嵌套的if语句工作流C＃

Question

This program is for validating Excel row data. If a if statement is false, I need to append a message to a string and so forth for N number of if statements. This doesn't work because as you can see if the first if statement fails, I would not proceed onto the the other if statements. Also later on, I'll need to handle 100+ columns, so I'm looking for a way to do this.

Is there any other way I can rewrite this, so it is more readable and less repetitive? I know I can just do a giant if (.... && ....) for validating all cells and individual if statements to append messages, but I was wondering if there is a another way to do this. I would like to preserve the order of the errors, but that is not as important. The result would be something like "facilityID is invalid, daysOfTheWeek is invalid" I'm also returning a custom Pair datatype.

string facilityID, facilityDockDoorID, increment, hoursOfOperationId, updatedById, startTime, endTime, dockDoorServiceType, daysOfTheWeek;
            facilityID = row[0];
            facilityDockDoorID = row[1];
            increment = row[2];
            hoursOfOperationId = row[3];
            updatedById = row[4];
            startTime = row[5];
            endTime = row[6];
            dockDoorServiceType = row[7];
            daysOfTheWeek = row[8];

            string errorMessage = " is invalid";
            if (IsInt(facilityID))
            {
                if (IsInt(facilityDockDoorID))
                {
                    if (IsInt(increment))
                    {
                        if (IsInt(hoursOfOperationId))
                        {
                            if (IsInt(updatedById))
                            {
                                if (IsTime(startTime))
                                {
                                    if (IsTime(endTime))
                                    {
                                        if (IsValidDockDoorServiceType(dockDoorServiceType))
                                        {
                                            if (IsValidDayOfTheWeek(daysOfTheWeek))
                                            {
                                                isDataValid.First = true;
                                            }
                                            else
                                            {
                                                isDataValid.Second += "daysOfTheWeek" + errorMessage + ",";                                                
                                            }
                                        }
                                        else
                                        {
                                            isDataValid.Second += "dockDoorServiceType" + errorMessage + ",";

                                        }
                                    }
                                    else
                                    {
                                        isDataValid.Second += "endTime" + errorMessage + ",";
                                    }
                                }
                                else
                                {
                                    isDataValid.Second += "startTime" + errorMessage + ",";
                                }
                            }
                            else
                            {
                                isDataValid.Second += "updatedById" + errorMessage + ",";
                            }
                        }
                        else
                        {
                            isDataValid.Second += "hoursOfOperationId" + errorMessage + ",";
                        }
                    }
                    else
                    {
                        isDataValid.Second += "increment" + errorMessage + ",";
                    }
                }
                else
                {
                    isDataValid.Second += "facilityDockDoorID" + errorMessage + ",";
                }
            }
            else
            {
                isDataValid.Second = "facilityID" + errorMessage + ",";
            }
            return isDataValid;
        }

Answer 1

If you invert the if statements and return inside each one you can flatten your code out like this.

if (!IsInt(facilityID))
{
    isDataValid.Second = "facilityID" + errorMessage + ",";
    return isDataValid;
}
if (!IsInt(facilityDockDoorID))
{
    isDataValid.Second += "facilityDockDoorID" + errorMessage + ",";
    return isDataValid;
}
if (!IsInt(increment))
{
    isDataValid.Second += "increment" + errorMessage + ",";
    return isDataValid;
}
if (!IsInt(hoursOfOperationId))
{
    isDataValid.Second += "hoursOfOperationId" + errorMessage + ",";
    return isDataValid;
}
if (!IsInt(updatedById))
{
    isDataValid.Second += "updatedById" + errorMessage + ",";
    return isDataValid;
}
if (!IsTime(startTime))
{
    isDataValid.Second += "startTime" + errorMessage + ",";
    return isDataValid;
}
if (!IsTime(endTime))
{
    isDataValid.Second += "endTime" + errorMessage + ",";
    return isDataValid;
}
if (!IsValidDockDoorServiceType(dockDoorServiceType))
{
    isDataValid.Second += "dockDoorServiceType" + errorMessage + ",";
    return isDataValid;
}
if (IsValidDayOfTheWeek(daysOfTheWeek))
{
    isDataValid.First = true;
}
else
{
    isDataValid.Second += "daysOfTheWeek" + errorMessage + ",";
}
return isDataValid;

However based on the fact that you are concatenating to Second it's more likely that you actually want something like

if (!IsInt(facilityID))
    isDataValid.Second = "facilityID" + errorMessage + ",";
if (!IsInt(facilityDockDoorID))
    isDataValid.Second += "facilityDockDoorID" + errorMessage + ",";
if (!IsInt(increment))
    isDataValid.Second += "increment" + errorMessage + ",";
if (!IsInt(hoursOfOperationId))
    isDataValid.Second += "hoursOfOperationId" + errorMessage + ",";
if (!IsInt(updatedById))
    isDataValid.Second += "updatedById" + errorMessage + ",";
if (!IsTime(startTime))
    isDataValid.Second += "startTime" + errorMessage + ",";
if (!IsTime(endTime))
    isDataValid.Second += "endTime" + errorMessage + ",";
if (!IsValidDockDoorServiceType(dockDoorServiceType))
    isDataValid.Second += "dockDoorServiceType" + errorMessage + ",";
if (!IsValidDayOfTheWeek(daysOfTheWeek))
    isDataValid.Second += "daysOfTheWeek" + errorMessage + ",";
isDataValid.First = isDataValid.Second.Length == 0;
return isDataValid;

Notice that I'm comparing the length of Second to determine if any errors occurred.

Answer 2

You could invert the if statements. For instance:

if(!IsInt(facilityID))
{
    isDataValid.Second = "facilityID" + errorMessage + ",";
}
if(!IsInt(facilityDockDoorID))
{
    isDataValid.Second += "facilityDockDoorID" + errorMessage + ",";
}

Answer 3

You could build a collection of validator functions, for example:

List<Func<string[], StringBuilder, bool>> validators = new List<Func<string[], StringBuilder, bool>>();

validators.Add((row, logger) => 
{
    string facilityID = row[0];

    if(IsInt(facilityID))
    {
        logger.AppendLine("facilityID is invalid");

        return false;
    }

    return true;
});

validators.Add((row, logger) =>
{
    string increment = row[2];

    if (IsInt(increment))
    {
        logger.AppendLine("increment is invalid");

        return false;
    }

    return true;
});

. . .

You can then just loop through all like so:

StringBuilder log = new StringBuilder();

if(validators.Any(v => v(rows, log) == false))
{
    return false;
}
else
{
    return true;
}

isDataValid.Second = log.ToString();

This way you can break the validator logic up until into smaller chunks. This avoid nesting the if statements. Each validator is responsible for picking the data it wants to validate, returning a valid/invalid bool , and logging any messages to the common StringBuilder . As your list of validators grows you can just add a new function to the collection.

Answer 4

It's best to break your schema apart from your code functionality. This allows you to change the schema in the future without having to change the rest of the code.

    public class SchemaItem
    {
        public int Index;
        public string ColumnName;
        public int ParsedValue;

        public SchemaItem(int index, string columnName)
        {
            Index = index;
            ColumnName = columnName;
        }
    }
    public static Dictionary<int, SchemaItem> Schema = new Dictionary<int, SchemaItem>
    {
        {0, new SchemaItem(0, "facilityID")},
        {1, new SchemaItem(1, "facilityDockDoorID")},
        {2, new SchemaItem(2, "increment")},
        {3, new SchemaItem(3, "hoursOfOperationId")},
        {4, new SchemaItem(4, "updatedById")},
        {5, new SchemaItem(5, "startTime")},
        {6, new SchemaItem(6, "endTime")},
        {7, new SchemaItem(7, "dockDoorServiceType")},
        {8, new SchemaItem(8, "daysOfTheWeek")},
    };
    private static bool ParseIntAndOrWriteFailMessage(string[] row, StringBuilder logger, int index)
    {
        string cellContents = row[index];
        string columnName = Schema[index].ColumnName;
        int intContents = -1;
        if (int.TryParse(cellContents, out intContents))
        {
            Schema[index].ParsedValue = intContents;
            return true;
        }
        logger.AppendFormat("{0} is invalid,", columnName);
        return false;
    }

Then finally you would do:

        StringBuilder logger = new StringBuilder();
        foreach (var column in Schema.Select(pair => pair))
        {
            ParseIntAndOrWriteFailMessage(row, logger, column.Key);
        }
        // Parsed values are now stored in the Schema Dictionary (which probably could use a better name)