I have a couple validators that is validating an IDeliveryObject, which conceptually can be described as a file with several rows. That part is working fine.
IEnumerable<IDeliveryValidator> _validators; // Populated in ctor. Usually around 20 different validators.
private IEnumerable<IValidationResult> Validate(IDeliveryObject deliveryObject)
{
var validationErrors = new List<IValidationResult>();
int maxNumberOfErrors = 10;
foreach (IDeliveryValidator deliveryValidator in _validators)
{
IEnumerable<IValidationResult> results = deliveryValidator.Validate(deliveryObject).Take(maxNumberOfErrors);
validationErrors.AddRange(results);
if (validationErrors.Count >= maxNumberOfErrors )
{
return validationErrors.Take(maxNumberOfErrors).ToList();
}
}
return validationErrors;
}
The logic iterates through a couple of validators, which all validates the file for different things.
And a validator can look something like this:
public IEnumerable<IValidationResult> Validate(IDeliveryObject deliveryObject)
{
using (var reader = File.OpenText(deliveryObject.FilePath))
{
int expectedLength = 10; // Or some other value.
string line;
while ((line = reader.ReadLine()) != null)
{
var lineLength = line.Length;
if (lineLength != expectedLength)
{
// yield an error for each incorrect row.
yield return new DeliveryValidationResult("Wrong length...");
}
}
}
}
The ValidationResult looks like this:
public class DeliveryValidationResult : ValidationResult, IValidationResult
{
public DeliveryValidationResult(bool isSoftError, string errorMessage) : base(errorMessage)
{
IsSoftError = isSoftError;
}
public DeliveryValidationResult(string errorMessage) : base(errorMessage)
{
}
public DeliveryValidationResult(string errorMessage, IEnumerable<string> memberNames) : base(errorMessage, memberNames)
{
}
public DeliveryValidationResult(ValidationResult validationResult) : base(validationResult)
{
}
public bool IsSoftError { get; set; }
}
public interface IValidationResult
{
string ErrorMessage { get; set; }
bool IsSoftError { get; set; }
}
Thanks to Take(maxNumberOfErrors) and yield each validator will only return 10 validationresults, which used to be fine. But now I need to handle "soft validation result", which is the same kind of validation result, but it should not be included in the number of results yielded. It's a kind of warning, which is defined by setting IsSoftError in IValidationResult. A validator can yield both "soft validation result" and "regular validation result".
What I want is to take x validation results + unlimited soft validation results, so that all IValidationResults with IsSoftError == true will be included in the collection, but not in the count. I know that it sounds weird, but the concept is that there's no need to keep validating the file after x errors, but the validation can return unlimited "warnings".
It's very important that the Enumeration isn't enumerated more than one time, because it's CPU-heavy. Below is the code I want to change.
private IEnumerable<IValidationResult> Validate(IDeliveryObject deliveryObject)
{
var validationErrors = new List<IValidationResult>();
int maxNumberOfErrors = 10;
foreach (IDeliveryValidator deliveryValidator in _validators)
{
// Here I want results to contain MAX 10 regular validation results, but unlimited soft validation results
IEnumerable<IValidationResult> results = deliveryValidator.Validate(deliveryObject).Take(maxNumberOfErrors);
validationErrors.AddRange(results);
if (validationErrors.Count(x => !x.IsSoftError) >= maxNumberOfErrors)
{
return validationErrors.Take(maxNumberOfErrors).ToList();
}
}
return validationErrors;
}
EDIT:
When I got 10 'hard' errors I want to stop the cycle completely. The main issue here is that the cycle doesn't stop when 10 'soft' errors occured.
In case you want to completely stop after 10 'hard' errors, you could try this:
int count = 0;
IEnumerable<IValidationResult> results = deliveryValidator.Validate(deliveryObject)
.TakeWhile(error => error.IsSoftError || count++ < maxNumberOfErrors);
this would stop when the 11th hard error is encountered.
//Go through all the items and sort them into Soft and NotSoft
//But ultimately these are in memory constructs...so this is fast.
var foo = Validate(delivery).ToLookup(x => x.IsSoftError);
var soft = foo[true];
var hard = foo[false].Take(10);
var result = Enumerable.Concat(soft, hard);
Related
I am updating the property of the list items.
class Response
{
public string Name { get; set; }
public int Order { get; set; }
}
Here I want to update the Order of a List<Response> variable. As of now, I am looping through each item of the list and updating it.
List<Response> data = FromDb();
foreach (var item in data)
{
if(item.Name.Equals("A"))
{
item.Order=1;
}
if(item.Name.Equals("B"))
{
item.Order=2;
}
//Like this I have arround 20 conditions
}
The above code is working fine, but the problem is the Cognitive Complexity of the method is more than the allowed.
I tried something like below
data.FirstOrDefault(x => x..Equals("A")).Order = 1;
data.FirstOrDefault(x => x..Equals("B")).Order = 2;
//and more ...
In this code also null check is not in place, So if the searching string is not present in the list then again it will break.
If I add null check condition then again the complexity getting higher.
So here I want without any for loop or if, If I can update the Order of the list by using linq/lamda or anything else.
I don't know how you measure Cognitive Complexity and how much of it is allowed to be pushed out into other functions, but something like this makes the ordering quite declarative?
[Fact]
public void TestIt()
{
var data = FromDb().Select(SetOrder(
("A", 1),
("B", 2)
));
}
static Func<Response, Response> SetOrder(params (string Name, int Order)[] orders)
{
var orderByKey = orders.ToDictionary(x => x.Name);
return response =>
{
if (orderByKey.TryGetValue(response.Name, out var result))
response.Order = result.Order;
return response;
};
}
Addendum in response to comment:
In order to have a default value for unmatched names, the SetOrder could be changed to this:
static Func<Response, Response> SetOrder(params (string Name, int Order)[] orders)
{
var orderByKey = orders.ToDictionary(x => x.Name);
return response =>
{
response.Order =
orderByKey.TryGetValue(response.Name, out var result)
? result.Order
: int.MaxValue;
return response;
};
}
I have an incoming list of alerts and I use a MapFunction as:
private static BPAlerts MapToAlerts(List<IntakeAlert> intakeAlerts)
{
// Make sure that there are alerts
if (intakeAlerts.IsNullOrEmpty()) return new BPAlerts { AllAlerts = new List<BPAlert>(), OverviewAlerts = new List<BPAlert>() };
// All Alerts
var alerts = new BPAlerts
{
AllAlerts = intakeAlerts.Select(
alert => new BPAlert
{
AlertTypeId = alert.AlertTypeId ?? 8100,
IsOverview = alert.IsOverviewAlert.GetValueOrDefault(),
Text = alert.AlertText,
Title = alert.AlertTitle,
Type = alert.AlertTypeId == 8106 ? "warning" : "report",
Severity = alert.AlertSeverity.GetValueOrDefault(),
Position = alert.Position.GetValueOrDefault()
}).OrderBy(a => a.Position).ToList()
};
// Alerts displayed on the overview page
alerts.OverviewAlerts =
alerts.AllAlerts
.ToList()
.Where(a => a.IsOverview && !string.IsNullOrEmpty(a.Title))
.Take(3)
.ToList();
return alerts;
}
the BPAlerts type contains list of two type:
public class BPAlerts
{
public List<BPAlert> AllAlerts { get; set; }
public List<BPAlert> OverviewAlerts { get; set; }
}
And the BPAlert type is defined as:
public class BPAlert
{
public short AlertTypeId { get; set; }
public string Type { get; set; }
public int Severity { get; set; }
public bool IsOverview { get; set; }
public string Title { get; set; }
public string Text { get; set; }
public int Position { get; set; }
public string Id { get; internal set; } = Guid.NewGuid().ToString();
}
I want to achieve a task in which the MaptoAlerts function returns a alerts object with overviewalerts which are sorted based on the type of BPAlert. To be more clear in the following order if present:
Confirmed Out of Business - 8106 \n
Bankruptcy - 8105 \n
Lack of Licensing - 8111 \n
Investigations - 8109 \n
Government Actions - 8103 \n
Pattern of Complaints - 8104 \n
Customer Reviews - 8112 \n
Accreditation - 8110 \n
Misuse of BBB Name - 8101 \n
Advisory - 8107 \n
Advertising Review – 8102 \n
Solution #1 Order values array
I would just define the order of those ids in some kind of collection, can be an array:
var orderArray = new int[]
{
8106, // Confirmed Out of Busine
8105, // Bankruptcy
8111, // Lack of Licensing
8109, // Investigations
8103, // Government Actions
8104, // Pattern of Complaints
8112, // Customer Reviews
8110, // Accreditation
8101, // Misuse of BBB Name
8107, // Advisory
8102, // Advertising Review
};
Then iterate through array while incrementing order value. While looping check if order array contains actual type id which order value I'm trying to evaluate:
for (int orderValue = 0; orderValue < orderArray.Length; orderValue++)
{
if (alertTypeId == orderArray[orderValue])
{
return orderValue;
}
}
If not found in the array, return highest value possible:
return int.MaxValue
Whole method would look like this and it would evaluate the order for alert type id:
public int GetAlertTypeIdOrder(short alertTypeId)
{
var orderArray = new int[]
{
8106, // Confirmed Out of Busine
8105, // Bankruptcy
8111, // Lack of Licensing
8109, // Investigations
8103, // Government Actions
8104, // Pattern of Complaints
8112, // Customer Reviews
8110, // Accreditation
8101, // Misuse of BBB Name
8107, // Advisory
8102, // Advertising Review
};
for (int orderValue = 0; orderValue < orderArray.Length; orderValue++)
{
if (alertTypeId == orderArray[orderValue])
{
return orderValue;
}
}
return int.MaxValue;
}
Usage:
var sortedAlerts = alerts
.AllAlerts
.OrderByDescending(a => GetAlertTypeIdOrder(a.AlertTypeId))
.ToList();
It also works in a descending way.
Solution #2 Order values dictionary
You could achieve better performance by reducing the redundancy - repeated creation of array storing order values. Better idea would be to store the order rules in a dictionary. I know that code below creates an array too, but the concept is that it would be called once to get the dictionary which would be then passed over.
public Dictionary<int, int> GetOrderRules()
{
var alertTypeIds = new int[]
{
8106, // Confirmed Out of Busine
8105, // Bankruptcy
8111, // Lack of Licensing
8109, // Investigations
8103, // Government Actions
8104, // Pattern of Complaints
8112, // Customer Reviews
8110, // Accreditation
8101, // Misuse of BBB Name
8107, // Advisory
8102, // Advertising Review
};
var orderRules = new Dictionary<int, int>();
for (int orderValue = 0; orderValue < alertTypeIds.Length; orderValue++)
{
orderRules.Add(alertTypeIds[orderValue], orderValue);
}
return orderRules;
}
So the GetAlertIdOrder() method would look different, but still keeping the idea from previous solution:
public int GetAlertIdOrder(short alertTypeId, IDictionary<int, int> orderRules)
{
if (orderRules.TryGetValue(alertTypeId, out int orderValue))
{
return orderValue;
}
else
{
return int.MaxValue;
}
}
Usage:
var orderRules = GetOrderRules();
var sortedAlerts = alerts
.AllAlerts
.OrderBy(a => GetAlertIdOrder(a.AlertTypeId, orderRules))
.ToList();
(a) I wouldn't mix sorting with the mapper. let the mapper just do its thing. (this is separation of concerns ) .. aka, no ordering/sorting. IMHO, you'll always end up with way too much voodoo in the mapper that is hard to understand. You're already on this path with the above code.
(b) if "OverviewAlerts" is a subset of AllAlerts (aka, AllAlerts is the superset), then hydrate AllAlerts, and create a read-only "get" property where you filter AllAlerts to your subset by its rules. optionally, consider a AllAlertsSorted get property. this way, you allow your consumers to choose if they want raw or sorted...since there is a cost with sorting.
public class BPAlerts
{
public List<BPAlert> AllAlerts { get; set; }
public List<BPAlert> OverviewAlerts {
get
{
return null == this.AllAlerts ? null : this.AllAlerts.Where (do you filtering and maybe sorting here ) ;
}
}
}
public List<BPAlert> AllAlertsSorted{
get
{
return null == this.AllAlerts ? null : this.AllAlerts.Sort(do you filtering and maybe sorting here ) ;
}
}
}
if you do the read-only properties, then you have more simple linq operations like
OrderBy(x => x.PropertyAbc).ThenByDescending(x => x.PropertyDef);
99% of my mapping code looks like this. I don't even throw an error if you give null input, i just return null.
public static class MyObjectMapper {
public static ICollection < MyOtherObject > ConvertToMyOtherObject(ICollection <MyObjectMapper> inputItems) {
ICollection <MyOtherObject> returnItems = null;
if (null != inputItems) {
returnItems = new List <MyOtherObject> ();
foreach(MyObjectMapper inputItem in inputItems) {
MyOtherObject moo = new MyOtherObject();
/* map here */
returnItems.Add(moo);
}
}
return returnItems;
}
}
Doing maintenance on a project I came across code, which I find unnecessary hard to read and I wish to refactor, to improve readability.
The functionality is a long chain of actions that need to be performed sequentially. The next action should only be handled if the previous action was successful. If an action is not successful a corresponding message needs to be set. And the returned type is a Boolean. (successful true/false). Just like the return type of all the called actions.
Basically it comes down to something like this.
string m = String.Empty; // This is the (error)Message.
bool x = true; // By default the result is succesful.
x = a1();
if(x) {
x = a2();
}
else {
m = "message of failure a1";
return x;
}
if(x) {
x = a3();
}
else {
m = "message of failure a2";
return x;
}
//etcetera..etcetera...
if(x){
m = "Success...";
}
else{
m = "Failure...";
}
return x;
My question is: What is a better structure / pattern to handle this kind of logic?
Main goals are:
increase readability.
increase maintainability.
Please keep in mind that it is quite a large chain of actions that is being performed sequentially. (Thousands lines of code)
Make a list of action/message pairs:
class Activity {
public Func<bool> Action { get; set; }
public String FailureMessage { get; set; }
}
Activity[] actionChain = new[] {
new Activity { Action = A1, FaulureMessage = "a1 failed"}
, new Activity { Action = A2, FaulureMessage = "a2 failed"}
, new Activity { Action = A3, FaulureMessage = "a3 failed"}
};
A1..A3 are no-argument methods returning bool. If some of your actions take parameters, you can use lambda expressions for them:
Activity[] actionChain = new[] {
...
, new Activity { Action = () => An(arg1, arg2), FaulureMessage = "aN failed"}
, ...
};
Now you can go through the pairs, and stop at the first failure:
foreach (var a in actionChain) {
if (!a.Action()) {
m = a.FailureMessage;
return false;
}
}
m = "Success";
return true;
#dasblinkenlight was faster... however a similar solution using yield instead of an array:
public string Evaluate()
{
foreach (var customAction in EnumerateActions())
{
if (!customAction.Execute())
return customAction.Error;
}
return "Success...";
}
public IEnumerable<CustomAction> EnumerateActions()
{
yield return new CustomAction(a1, "Error for A1");
yield return new CustomAction(a2, "Error for A2");
...
}
public class CustomAction
{
public Func<bool> Execute { get; }
public string Error { get; }
public CustomAction(Func<bool> action, string error)
{
Execute = action;
Error = error;
}
}
This is really a generic (and probably a more subjective too) question. I have some classes where I use an interface to define a standard approach to validating the object state. When I did this, I got to scratching my head... is it best to
1.) allow the constructor (or initializing method) to silently filter out the errant information automatically or...
2.) allow the client to instantiate the object however and let the client also call the interface's IsValid property or Validate() method before moving forward?
Basically one approach is silent but could be misleading in that the client may not be aware that certain pieces of information were filtered away due to it not meeting the validation criteria. The other approach then would be more straight forward, but also adds a step or two? What's typical here?
Okay, after a long day of trying to keep up with some other things, I finally did come up with an example. Please for me for it as it's not ideal and by no means something wonderful, but hopefully should serve well enough to get the point across. My current project is just too complicated to put something simple out for this, so I made something up... and trust me... totally made up.
Alright, the objects in the example are this:
Client: representing client-side code (Console App btw)
IValidationInfo: This is the actual interface I'm using in my current project. It allows me to create a validation framework for the "back-end" objects not necessarily intended for the Client to use since the business logic could be complicated enough. This also allowed me to separate validation code and call as-needed for the business logic.
OrderManager: This is an object the client-side code can use to manage their orders. It's client-friendly so-to-speak.
OrderSpecification: This is an object the client-side code can use to request an order. But if the business logic doesn't work out, an exception can be raised (or if necessary the order not added and exceptions ignored...) In my real-world example I actually have an object that's not quite so black-and-white as to which side of this fence it goes... thus my original question when I realized I could push validation request (calling IsValid or Validate()) to the cilent.
CustomerDescription: represents customers to which I've classified (pretending to have been read from a DB.
Product: Represents a particular product which is classified also.
OrderDescription: Represents the official order request.The business rule is that the Customer cannot order anything to which they've not been classified (I know.. that's not very real-world, but it gave me something to work with...)
Ok... I just realized I can't attach a file here, so here's the code. I apologize for it's lengthy appearance. That was the best I could do to create a client-friendly front-end and business logic back-end using my Validation interface:
public class Client
{
static OrderManager orderMgr = new OrderManager();
static void Main(string[] args)
{
//Request a new order
//Note: Only the OrderManager and OrderSpecification are used by the Client as to keep the
// Client from having to know and understand the framework beyond that point.
OrderSpecification orderSpec = new OrderSpecification("Customer1", new Product(IndustryCategory.FoodServices, "Vending Items"));
orderMgr.SubmitOrderRequest(orderSpec);
Console.WriteLine("The OrderManager has {0} items for {1} customers.", orderMgr.ProductCount, orderMgr.CustomerCount);
//Now add a second item proving that the business logic to add for an existing customer works
Console.WriteLine("Adding another valid item for the same customer.");
orderSpec = new OrderSpecification("Customer1", new Product(IndustryCategory.FoodServices, "Sodas"));
orderMgr.SubmitOrderRequest(orderSpec);
Console.WriteLine("The OrderManager now has {0} items for {1} customers.", orderMgr.ProductCount, orderMgr.CustomerCount);
Console.WriteLine("Adding a new valid order for a new customer.");
orderSpec = new OrderSpecification("Customer2", new Product(IndustryCategory.Residential, "Magazines"));
orderMgr.SubmitOrderRequest(orderSpec);
Console.WriteLine("The OrderManager now has {0} items for {1} customers.", orderMgr.ProductCount, orderMgr.CustomerCount);
Console.WriteLine("Adding a invalid one will not work because the customer is not set up to receive these kinds of items. Should get an exception with message...");
try
{
orderSpec = new OrderSpecification("Customer3", new Product(IndustryCategory.Residential, "Magazines"));
orderMgr.SubmitOrderRequest(orderSpec);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.ReadLine();
}
}
public interface IValidationInfo
{
string[] ValidationItems { get; }
bool IsValid { get; }
void Validate();
List<string> GetValidationErrors();
string GetValidationError(string itemName);
}
public class OrderManager
{
private List<OrderDescription> _orders = new List<OrderDescription>();
public List<OrderDescription> Orders
{
get { return new List<OrderDescription>(_orders); }
private set { _orders = value; }
}
public int ProductCount
{
get
{
int itemCount = 0;
this.Orders.ForEach(o => itemCount += o.Products.Count);
return itemCount;
}
}
public int CustomerCount
{
get
{
//since there's only one customer per order, just return the number of orders
return this.Orders.Count;
}
}
public void SubmitOrderRequest(OrderSpecification orderSpec)
{
if (orderSpec.IsValid)
{
List<OrderDescription> orders = this.Orders;
//Since the particular customer may already have an order, we might as well add to an existing
OrderDescription existingOrder = orders.FirstOrDefault(o => string.Compare(orderSpec.Order.Customer.Name, o.Customer.Name, true) == 0) as OrderDescription;
if (existingOrder != null)
{
List<Product> existingProducts = orderSpec.Order.Products;
orderSpec.Order.Products.ForEach(p => existingOrder.AddProduct(p));
}
else
{
orders.Add(orderSpec.Order);
}
this.Orders = orders;
}
else
orderSpec.Validate(); //Let the OrderSpecification pass the business logic validation down the chain
}
}
public enum IndustryCategory
{
Residential,
Textile,
FoodServices,
Something
}
public class OrderSpecification : IValidationInfo
{
public OrderDescription Order { get; private set; }
public OrderSpecification(string customerName, Product product)
{
//Should use a method in the class to search and retrieve Customer... pretending here
CustomerDescription customer = null;
switch (customerName)
{
case "Customer1":
customer = new CustomerDescription() { Name = customerName, Category = IndustryCategory.FoodServices };
break;
case "Customer2":
customer = new CustomerDescription() { Name = customerName, Category = IndustryCategory.Residential };
break;
case "Customer3":
customer = new CustomerDescription() { Name = customerName, Category = IndustryCategory.Textile };
break;
}
//Create an OrderDescription to potentially represent the order... valid or not since this is
//a specification being used to request the order
this.Order = new OrderDescription(new List<Product>() { product }, customer);
}
#region IValidationInfo Members
private readonly string[] _validationItems =
{
"OrderDescription"
};
public string[] ValidationItems
{
get { return _validationItems; }
}
public bool IsValid
{
get
{
List<string> validationErrors = GetValidationErrors();
if (validationErrors != null && validationErrors.Count > 0)
return false;
else
return true;
}
}
public void Validate()
{
List<string> errorMessages = GetValidationErrors();
if (errorMessages != null && errorMessages.Count > 0)
{
StringBuilder errorMessageReported = new StringBuilder();
errorMessages.ForEach(em => errorMessageReported.AppendLine(em));
throw new Exception(errorMessageReported.ToString());
}
}
public List<string> GetValidationErrors()
{
List<string> errorMessages = new List<string>();
foreach (string item in this.ValidationItems)
{
string errorMessage = GetValidationError(item);
if (!string.IsNullOrEmpty(errorMessage))
errorMessages.Add(errorMessage);
}
return errorMessages;
}
public string GetValidationError(string itemName)
{
switch (itemName)
{
case "OrderDescription":
return ValidateOrderDescription();
default:
return "Invalid item name.";
}
}
#endregion
private string ValidateOrderDescription()
{
string errorMessage = string.Empty;
if (this.Order == null)
errorMessage = "Order was not instantiated.";
else
{
if (!this.Order.IsValid)
{
List<string> orderErrors = this.Order.GetValidationErrors();
orderErrors.ForEach(ce => errorMessage += "\n" + ce);
}
}
return errorMessage;
}
}
public class CustomerDescription : IValidationInfo
{
public string Name { get; set; }
public string Street { get; set; }
public string City { get; set; }
public string State { get; set; }
public int ZipCode { get; set; }
public IndustryCategory Category { get; set; }
#region IValidationInfo Members
private readonly string[] _validationItems =
{
"Name",
"Street",
"City",
"State",
"ZipCode",
"Category"
};
public string[] ValidationItems
{
get { return _validationItems; }
}
public bool IsValid
{
get
{
List<string> validationErrors = GetValidationErrors();
if (validationErrors != null && validationErrors.Count > 0)
return false;
else
return true;
}
}
public void Validate()
{
List<string> errorMessages = GetValidationErrors();
if (errorMessages != null && errorMessages.Count > 0)
{
StringBuilder errorMessageReported = new StringBuilder();
errorMessages.ForEach(em => errorMessageReported.AppendLine(em));
throw new Exception(errorMessageReported.ToString());
}
}
public List<string> GetValidationErrors()
{
List<string> errorMessages = new List<string>();
foreach (string item in this.ValidationItems)
{
string errorMessage = GetValidationError(item);
if (!string.IsNullOrEmpty(errorMessage))
errorMessages.Add(errorMessage);
}
return errorMessages;
}
public string GetValidationError(string itemName)
{
//Validation methods should be called here... pretending nothings wrong for sake of discussion & simplicity
switch (itemName)
{
case "Name":
return string.Empty;
case "Street":
return string.Empty;
case "City":
return string.Empty;
case "State":
return string.Empty;
case "ZipCode":
return string.Empty;
case "Category":
return string.Empty;
default:
return "Invalid item name.";
}
}
#endregion
}
public class Product
{
public IndustryCategory Category { get; private set; }
public string Description { get; private set; }
public Product(IndustryCategory category, string description)
{
this.Category = category;
this.Description = description;
}
}
public class OrderDescription : IValidationInfo
{
public CustomerDescription Customer { get; private set; }
private List<Product> _products = new List<Product>();
public List<Product> Products
{
get { return new List<Product>(_products); }
private set { _products = value; }
}
public OrderDescription(List<Product> products, CustomerDescription customer)
{
this.Products = products;
this.Customer = customer;
}
public void PlaceOrder()
{
//If order valid, place
if (this.IsValid)
{
//Do stuff to place order
}
else
Validate(); //cause the exceptions to be raised with the validate because business rules were broken
}
public void AddProduct(Product product)
{
List<Product> productsToEvaluate = this.Products;
//some special read, validation, quantity check, pre-existing, etc here
// doing other stuff...
productsToEvaluate.Add(product);
this.Products = productsToEvaluate;
}
#region IValidationInfo Members
private readonly string[] _validationItems =
{
"Customer",
"Products"
};
public string[] ValidationItems
{
get { return _validationItems; }
}
public bool IsValid
{
get
{
List<string> validationErrors = GetValidationErrors();
if (validationErrors != null && validationErrors.Count > 0)
return false;
else
return true;
}
}
public void Validate()
{
List<string> errorMessages = GetValidationErrors();
if (errorMessages != null && errorMessages.Count > 0)
{
StringBuilder errorMessageReported = new StringBuilder();
errorMessages.ForEach(em => errorMessageReported.AppendLine(em));
throw new Exception(errorMessageReported.ToString());
}
}
public List<string> GetValidationErrors()
{
List<string> errorMessages = new List<string>();
foreach (string item in this.ValidationItems)
{
string errorMessage = GetValidationError(item);
if (!string.IsNullOrEmpty(errorMessage))
errorMessages.Add(errorMessage);
}
return errorMessages;
}
public string GetValidationError(string itemName)
{
switch (itemName)
{
case "Customer":
return ValidateCustomer();
case "Products":
return ValidateProducts();
default:
return "Invalid item name.";
}
}
#endregion
#region Validation Methods
private string ValidateCustomer()
{
string errorMessage = string.Empty;
if (this.Customer == null)
errorMessage = "CustomerDescription is missing a valid value.";
else
{
if (!this.Customer.IsValid)
{
List<string> customerErrors = this.Customer.GetValidationErrors();
customerErrors.ForEach(ce => errorMessage += "\n" + ce);
}
}
return errorMessage;
}
private string ValidateProducts()
{
string errorMessage = string.Empty;
if (this.Products == null || this.Products.Count <= 0)
errorMessage = "Invalid Order. Missing Products.";
else
{
foreach (Product product in this.Products)
{
if (product.Category != Customer.Category)
{
errorMessage += string.Format("\nThe Product, {0}, category does not match the required Customer category for {1}", product.Description, Customer.Name);
}
}
}
return errorMessage;
}
#endregion
}
Any reason you wouldn't want the constructor to noisily throw an exception if the information is valid? It's best to avoid ever creating an object in an invalid state, in my experience.
It's completely depends on the client. There's a trade-off as you already mentioned. By default approach number 1 is my favorite. Creating smart classes with good encapsulation and hiding details from client. The level of smartness depends who is going to use the object. If client is business aware you can reveal details according to the level of this awareness. This is a dichotomy and should not be treated as black or white.
Well if I correctly understood, there are basically two question - whether you should fail right away or later and whether you should omit/assume certain information.
1) I always prefer failing as soon as possible - good example is failing at compile time vs failing at run time - you always want to fail at compile time. So if something is wrong with the state of some object, as Jon said - throw exception right away as loudly as you can and deal with it - do not introduce additional complexity down the road as you'll be heading for if/elseif/elseif/elseif/else mumbo jumbo.
2) When it comes to user input, if you are in position to simply filter out errors automatically - just do it. For example, I almost never ask users for country - if I really need it, I automatically detect it from IP and display it in the form. It's way easier if user just needs to confirm/change the data - and I don't need to deal with null situation.
Now, in case we are talking about the data generated by code during some processing - for me situation is drastically different - I always want to know an much as possible (for easier debugging down the road) and ideally you never should destroy any piece of information.
To wrap up, in your case I would recommend that you keep IsValid as simple yes/no (not yes/no/maybe/kindaok/etc). If you can fix some problems automatically - do it, but consider that they keep object in IsValid yes. For everything else, you throw exception and go to IsValid=no.
I am trying to find all the zones that contain 2 or more zone members where the search term is a string value. Here is the code I have. In the FindCommmonZones method when I try to cast the result of an Intersect to an ObservableCollection I get a run-time on an invalid cast. The question is, is there a better way to do this? The string array that is the paramter for FindCommonZones() can be any count of strings. StackOverflow had some other similar posts but none really answered my question - it looked like they all pertained more to SQL.
Some code:
public class Zone
{
public List<ZoneMember> MembersList = new List<ZoneMember>();
private string _ZoneName;
public string zoneName{ get{return _ZoneName;} set{_ZoneName=value;} }
public Zone ContainsMember(string member)
{
var contained = this.MembersList.FirstOrDefault(m => m.MemberWWPN.
Contains(member) || m.MemberAlias.Contains(member));
if (contained != null) { return this; }
else { return null; }
}
}
public class ZoneMember
// a zone member is a member of a zone
// zones have ports, WWPNs, aliases or all 3
{
private string _Alias = string.Empty;
public string MemberAlias {get{return _Alias;} set{_Alias = value; } }
private FCPort _Port = null;
public FCPort MemberPort { get { return _Port; } set { _Port = value; } }
private string _WWPN = string.Empty;
public string MemberWWPN { get { return _WWPN; } set { _WWPN = value; } }
private bool _IsLoggedIn;
public bool IsLoggedIn { get { return _IsLoggedIn; } set { _IsLoggedIn = value; } }
private string _FCID;
public string FCID {get{return _FCID;} set{ _FCID=value; } }
}
private ObservableCollection<ZoneResult> FindCommonZones(string[] searchterms)
{
ObservableCollection<ZoneResult> tempcollection =
new ObservableCollection<ZoneResult>();
//find the zones for the first search term
tempcollection = this.FindZones(searchterms[0]);
//now search for the rest of the search terms and compare
//them to existing result
for (int i = 1; i < searchterms.Count(); i++ )
{
// this line gives an exception trying to cast
tempcollection = (ObservableCollection<ZoneResult>)tempcollection.
Intersect(this.FindZones(searchterms[i]));
}
return tempcollection;
}
private ObservableCollection<ZoneResult> FindZones(string searchterm)
// we need to track the vsan where the zone member is found
// so use a foreach to keep track
{
ObservableCollection<ZoneResult> zonecollection = new ObservableCollection<ZoneResult>();
foreach (KeyValuePair<int, Dictionary<int, CiscoVSAN>> fabricpair in this.FabricDictionary)
{
foreach (KeyValuePair<int, CiscoVSAN> vsanpair in fabricpair.Value)
{
var selection = vsanpair.Value.ActiveZoneset.
ZoneList.Select(z => z.ContainsMember(searchterm)).
Where(m => m != null).OrderBy(z => z.zoneName);
if (selection.Count() > 0)
{
foreach (Zone zone in selection)
{
foreach (ZoneMember zm in zone.MembersList)
{
ZoneResult zr = new ZoneResult(zone.zoneName,
zm.MemberWWPN, zm.MemberAlias, vsanpair.Key.ToString());
zonecollection.Add(zr);
}
}
}
}
}
return zonecollection;
}
Intersect is actually Enumerable.Intersect and is returning an IEnumerable<ZoneResult>. This is not castable to an ObservableCollection because it isn't one - it is the enumeration of the intersecting elements in both collections.
You can, however create a new ObservableCollection from the enumeration:
tempcollection = new ObservableCollection<ZoneResult>(tempcollection
.Intersect(this.FindZones(searchterms[i]));
Depending on how many elements you have, how ZoneResult.Equals is implemented, and how many search terms you expect, this implementation may or may not be feasable (FindZones does seem a little overly-complicated with O(n^4) at first glance). If it seems to be a resource hog or bottleneck, it's time to optimize; otherwise I would just leave it alone if it works.
One suggested optimization could be the following (incorporating #Keith's suggestion to change ContainsMember to a bool) - although it is untested, I probably have my SelectManys wrong, and it really largely amounts to the same thing, you hopefully get the idea:
private ObservableCollection<ZoneResult> FindCommonZones(string[] searchterms)
{
var query = this.FabricDictionary.SelectMany(fabricpair =>
fabricpair.Value.SelectMany(vsanpair =>
vsanpair.Value.ActiveZoneSet.ZoneList
.Where(z=>searchterms.Any(term=>z.ContainsMember(term)))
.SelectMany(zone =>
zone.MembersList.Select(zm=>new ZoneResult(zone.zoneName, zm.MemberWWPN, zm.MemberAlias, vsanpair.Key.ToString()))
)
)
.Distinct()
.OrderBy(zr=>zr.zoneName);
return new ObservableCollection<ZoneResult>(query);
}