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Questions tagged [validation]

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579 votes
1 answer
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Is the use of "utf8=✓" preferable to "utf8=true"?

I have recently seen a few URIs containing the query parameter "utf8=✓". My first impression (after thinking "mmm, looks cool") was that this could be used to detect a broken character encoding. So, ...
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108 votes
25 answers
36k views

How far should one take e-mail address validation?

I'm wondering how far people should take the validation of e-mail address. My field is primarily web-development, but this applies anywhere. I've seen a few approaches: simply checking if there is ...
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  • 1,249
70 votes
7 answers
25k views

If functions have to do null checks before doing the intended behaviour is this bad design?

So I don't know if this is good or bad code design so I thought I better ask. I frequently create methods that do data processing involving classes and I often do a lot of checks in the methods to ...
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  • 1,953
53 votes
10 answers
33k views

Should a method validate its parameters? [duplicate]

Say you are designing a Square root method sqrt. Do you prefer to validate the parameter passed is not a negative number or do you leave it up to the caller to make sure the param passed is valid. How ...
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  • 1,932
47 votes
4 answers
23k views

Where we should put validation for domain model

I still looking best practice for domain model validation. Is that good to put the validation in constructor of domain model ? my domain model validation example as follows: public class Order { ...
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44 votes
8 answers
4k views

Should I throw an exception in case of a meaningful value outside of the range or handle it myself?

I have written a struct that represents latitude/longitude coordinates. Their values range from -180 to 180 for longtitudes and 90 to -90 for lattitudes. If a user of that struct gives me a value ...
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43 votes
8 answers
8k views

Is it common practice to validate responses from 3rd party APIs?

I'm working on a PHP web application that depends on a few 3rd-party services. These services are well documented and provided by fairly large organisations. I feel paranoid when working with ...
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39 votes
9 answers
44k views

Constructor parameter validation in C# - Best practices

What is the best practice for constructor parameter validation? Suppose a simple bit of C#: public class MyClass { public MyClass(string text) { if (String.IsNullOrEmpty(text)) ...
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  • 2,028
33 votes
21 answers
10k views

Is Software Testing Really Needed?

I'm a student working on my B.E(CS) and my question is the following: Is testing in the software field needed? If we create a software with great care, then why should we test? After testing can ...
30 votes
7 answers
7k views

Should I validate a method call's return value even if I know that the method can't return bad input?

I'm wondering if I should defend against a method call's return value by validating that they meet my expectations even if I know that the method I'm calling will meet such expectations. GIVEN User ...
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  • 1,277
30 votes
5 answers
10k views

Data input validation - Where? How much? [closed]

Data input validation always was quite an internal struggle to me. On the verge of adding a real security framework and code to our legacy application rewrite project (which so far pretty much keeps ...
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  • 469
28 votes
6 answers
31k views

In which layer should validation be located?

I'm creating a Rest API using Spring Boot and I am using Hibernate Validation to validate request inputs. But I also need other kinds of validation, for example when update data needs to checked, if ...
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  • 381
27 votes
6 answers
5k views

Is it ok to have validation layer before access control layer

I am creating an API strcutured web application and in this application we have different layers which are doing their own job. First layer is Validation layer which validate user input and if it ...
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  • 389
25 votes
4 answers
6k views

Is client-side validation really all that important, always? [duplicate]

Through the years I've worked in web development it's been ingrained in me that client-side validation is absolutely and completely necessary in all web applications. Seems to me like all the people ...
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  • 1,033
21 votes
6 answers
34k views

What Special characters should one allow for a Phone Number?

So I am designing a webpage which will be used for global users, includes users from Canada, US, India, UK etc. I need to apply validations for this phone number field, but I'm not sure the best way ...
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  • 973
20 votes
9 answers
2k views

Is an 'if password == XXXXXXX' enough for minimum security?

If I create a login for an app that has middle to low security risk (in other words, its not a banking app or anything), is it acceptable for me to verify a password entered by the user by just saying ...
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20 votes
4 answers
12k views

Clean architecture validation in domain vs data persistence layer?

I'm studying up on clean and as a result am quite dramatically rethinking a great deal of how I design and write software. I've thing I'm still wrestling with however, is for business rules like "on ...
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20 votes
6 answers
12k views

Validation of the input parameter in caller: code duplication?

Where is the best place to validate input parameters of function: in caller or in function itself? As I would like to improve my coding style, I try to find the best practices or some rules for this ...
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  • 345
19 votes
4 answers
7k views

Managing client-side and server-side validations in one place

I'm 100% on board with the case that one should definitely use both client-side and server-side data validations. However, in the frameworks and environments I've worked in, the approaches I've seen ...
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  • 2,331
19 votes
2 answers
20k views

Data validation: separated class or not?

When I have a lot of data that needs to be validated, should I create a new class for the sole purpose of validation or should I stick with in-method validation? My particular example contemplates a ...
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  • 2,106
18 votes
9 answers
20k views

When should pointers be checked for NULL in C?

Summary: Should a function in C always check to make sure it is not dereferencing a NULL pointer? If not when is it appropriate to skip these checks? Details: I've been reading some books about ...
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17 votes
4 answers
818 views

Is validating HTML a thing of the past? [duplicate]

With us moving continually closer to HTML5 in terms of adoption, is writing HTML for validity something the web is rejecting, allowing us to straddle standards as the web continues to be in a ...
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13 votes
5 answers
2k views

For an ORM supporting data validation, should constraints be enforced in the database as well?

I have always applied constraints at the database level in addition to my (ActiveRecord) models. But I've been wondering if this is really required? A little background I recently had to unit test a ...
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  • 235
13 votes
6 answers
13k views

How should I handle invalid user input?

I have been thinking about this issue for a while and I would be curious to have opinions from other developers. I tend to have a very defensive style of programming. My typical block or method looks ...
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  • 19.1k
13 votes
3 answers
5k views

Validation and authorization in layered architecture

I know you are thinking (or maybe yelling), "not another question asking where validation belongs in a layered architecture?!?" Well, yes, but hopefully this will be a little bit of a different take ...
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  • 2,845
12 votes
5 answers
995 views

Strengthening code with possibly useless exception handling

Is it a good practice to implement useless exception handling, just in case another part of the code is not coded correctly? Basic example A simple one, so I don't loose everybody :). Let's say I'm ...
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  • 453
12 votes
4 answers
1k views

How defensive should we be?

We've been running Pex over some code, and it has been showing some good things (well bad things, but showing them before it gets to production!). However, one of the nice things about Pex is that it ...
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  • 3,807
12 votes
3 answers
5k views

IValidatableObject vs Single Responsibility

I like the extnesibility point of MVC, allowing view models to implement IValidatableObject, and add custom validation. I try to keep my Controllers lean, having this code be the only validation ...
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  • 3,538
11 votes
3 answers
1k views

How to perform input validation without exceptions or redundancy

When I'm trying to create an interface for a specific program I'm generally trying to avoid throwing exceptions that depend on non-validated input. So what often happens is that I've thought of a ...
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11 votes
2 answers
6k views

Has anyone successfully used Windows Workflow for a Business Rules/Validation engine?

I was wondering if anyone has successfully used Windows Workflow Foundation for a BusinessRules/Validation engine, or if you know of some sample code or articles about this. If you have used it ...
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  • 23.9k
11 votes
2 answers
4k views

Where to validate domain model rules that depend on database content?

I'm working on a system that allows Administrators to define Forms that contain Fields. The defined Forms are then used to enter data to the system. Sometimes the Forms are filled by a human via a GUI,...
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11 votes
1 answer
5k views

Duck typing, data validation and assertive programming in Python

About duck typing: Duck typing is aided by habitually not testing for the type of arguments in method and function bodies, relying on documentation, clear code and testing to ensure correct use. ...
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  • 362
11 votes
2 answers
7k views

Command handlers and DDD

I have an ASP.NET MVC application, that uses a query service to get data and a command service to send commands. My question is about the command part. If a request comes in, the command service uses ...
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  • 333
11 votes
2 answers
3k views

Where should you validate the state of "other" aggregates?

Scenario: A customer places an order, then, after receiving the product, provides feedback on the order process. Assume the following aggregate roots: Customer Order Feedback Here are the business ...
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  • 614
10 votes
5 answers
10k views

Do you use both Client-side and Server-side validation techniques?

Do you use both Client-side and Server-side validation techniques side by side when validating input from a user, e.g. via a contact form? If so, is it really necessary? Are you over engineering?
user avatar
10 votes
6 answers
4k views

If the model is validating the data, shouldn't it throw exceptions on bad input?

Reading this SO question it seems that throwing exceptions for validating user input is frowned upon. But who should validate this data? In my applications, all validations are done in the business ...
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10 votes
2 answers
23k views

Name validation best practices

I have a form and I was wondering about best practices when validating names (specifically throwing out characters which do not typically make up a name e.g. 123%^*$£ though theoretically could) and ...
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  • 231
9 votes
6 answers
5k views

Why is it bad to use exceptions for handling this type of validation? It seems like it makes the code so much cleaner

I'm working on a .NET Core REST API and I'm writing a service class to create new user accounts. I have the following code: public async Task<UserDto> RegisterNewUserAccount(...
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9 votes
1 answer
1k views

Better to use error monad with validation in your monadic functions, or implement your own monad with validation directly in your bind?

I'm wondering what's better design wise for usability/maintainability, and what's better as far as fitting with the community. Given the data model: type Name = String data Amount = Out | Some | ...
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  • 15.9k
8 votes
2 answers
2k views

What is best practice to handle whitespaces when letting the user edit the configuration, the name=value pairs?

For instance, you let the user define the notorious path variable. How do you interpret apppath = C:\Program Files\App? This looks like a programming language adopted practice to ignore the white ...
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  • 1
8 votes
2 answers
887 views

How come verification does not include actual testing?

Having read a lot about this topic --- such as on this Software Testing Fundamentals site on verification and validation and Software Testing and Quality Assurance: Theory and Practice by Naik and ...
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  • 4,878
8 votes
5 answers
1k views

Message validation in async messaging-based services

I'm looking for information on the best approach to message validation in asynchronous-messaging-based services (i.e. services that pull messages from some sort of message queue or broker, rather than ...
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  • 1,045
7 votes
8 answers
891 views

Do objects with validation logic in their domain really represent their real world counterparts?

I asked a question about whether validation behavior should be treated the same as other types of behavior in regard to the concept of OOP being "data + behavior". I got some good answers back that ...
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  • 459
7 votes
3 answers
1k views

Is it a bad idea to do validation in the constructor?

Consider the following approach to validation of an API class (POJO or what have you, I mean a class which just acts as a container for some properties), we make all constructors private to the API ...
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7 votes
2 answers
3k views

How is the Trial Period for Softwares generally implemented?

I was always under the assumption that trial softwares write a registry value of the installation date and then the software makes a comparison of the current date of the system with the remaining ...
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  • 1,543
7 votes
3 answers
438 views

How to measure external quality of software

For my thesis, I am doing research into the characteristics of Behavior Driven Development (BDD). One of the BDD claims is that by specifying the requirements in a ubiquitous language together with ...
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7 votes
1 answer
6k views

Writing a valid test case for validating XMLs

How would I write a unit test, say JUnit, for validating an XML file? I have an application that creates a document as an XML file. In order to validate this XML structure, do I need to create an XML ...
user avatar
7 votes
2 answers
5k views

Guidelines for returning None vs. raising Error for Python string-validating functions

Let's say we have a function that checks if a given pattern occurs in a string. The default behaviour is that if the pattern matches, then it returns the pattern. So far so good but what is the ...
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  • 171
6 votes
3 answers
5k views

OOP: Behavior + Data, but what about 'validation' behaviors?

EDIT: Thanks for all the great answers! In reading these responses I realized that I'm approaching this from the wrong angle so I wrote a new question here. I had this discussion with my superior ...
user avatar
  • 459
6 votes
2 answers
2k views

Is server validation necessary with client-side validators?

I recently created a .net web app that used over 200 custom validators on one page. I wrote code for both ClientValidationFunction and OnServerValidate which results in a ton of repetitive code. My ...
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