Add some extensions methods for validation by rodriguestiago0 · Pull Request #518 · fsprojects/FSharpPlus

rodriguestiago0 · 2022-11-14T21:15:52Z

No description provided.

… methods

gusty · 2022-11-14T21:39:55Z

src/FSharpPlus/Data/Validation.fs

+    [<AutoOpen>]
+    module ComputationExpression =
+        type ValidationBuilder() =
+            member _.Bind(x, f) =
+                match x with
+                | Failure e -> Failure e
+                | Success a -> f a
+
+            member _.MergeSources(left : Validation<list<string>, _>, right : Validation<list<string>, _>) =
+                match left, right with
+                | Success l, Success r -> Success (l, r)
+                | Failure l, Success _ -> Failure l
+                | Success _, Failure r -> Failure r
+                | Failure r, Failure l -> List.append r l |> Failure
+
+            member _.Return(x) =
+                Success x
+
+            member _.ReturnFrom(x) =
+                x
+
+        let validator = ValidationBuilder()


Note that this is just a special case of the applicative computation expression, closed to Validation<list<string>, 'T>.

I mean, right now you can just define it like: let validator<'T> = applicative<Validation<list<string>, 'T>> and you'll have the same methods and more available.

Actually the bind is not part of the applicative CE, but Validation is not a monad, as it doesn't obey monad rules. However in order to get the short-circuit behavior you can use let validator<'T> = monad'<Result<'T, List<string>>

Maybe an alias then?

gusty · 2022-11-14T21:45:18Z

src/FSharpPlus/Extensions/Validation.fs

+
+    let inline requireString propName =
+        let errorMessage =
+            sprintf "%s cannot be null, empty or whitespace." propName


In my experience using string as errors doesn't scale well, unless they are at the boundaries with the user.
But otherwise, validations errors should be represented with a custom type, normally a DU, which should be directly related to the business model of validation errors.

Having said that, we could add an additional parameter which is a function that creates the error, so the user is free to supply whatever structure he uses.

@rodriguestiago0

Error strings must be declared as public static functions to be available for plain reuse (for example in unit tests)

We have a case right now when we need to delay error string creation till it is required:
a. Output to log as is
b. Output to API response with camel case field name modification

I know to let the user define the Error to be added. It can be a string, int or whatever the developer wants.

xperiandri · 2022-11-15T04:43:55Z

src/FSharpPlus/Data/Validation.fs

+    [<AutoOpen>]
+    module ComputationExpression =
+        type ValidationBuilder() =
+            member _.Bind(x, f) =
+                match x with
+                | Failure e -> Failure e
+                | Success a -> f a
+
+            member _.MergeSources(left : Validation<list<string>, _>, right : Validation<list<string>, _>) =
+                match left, right with
+                | Success l, Success r -> Success (l, r)
+                | Failure l, Success _ -> Failure l
+                | Success _, Failure r -> Failure r
+                | Failure r, Failure l -> List.append r l |> Failure
+
+            member _.Return(x) =
+                Success x
+
+            member _.ReturnFrom(x) =
+                x
+
+        let validator = ValidationBuilder()


Maybe an alias then?

gusty · 2022-11-15T05:53:42Z

Maybe an alias then?

That's an old discussion we have here.
This library contains highly reusable code
We can create a module with some CEs, but as you can see defining aliases are one-liner.

My original view was that F#+ is kind of a library for libraries, meaning that you can have your own enterprise specific libraries where you take what you need, the way you need, this is giving a specific name and closing it over certain type parameters.

I had feedback that some users did that at the beginning, which lead to the desire of making CEs more parameterizable, we did that in v1.2

However, if everybody is strongly for providing aliases we can evaluate the impact. Maybe provide a script with those aliases or a separate package.

tests/FSharpPlus.Tests/Validations.fs

src/FSharpPlus/Extensions/Validation.fs

…estiago0/FSharpPlus into rodrigues/add-validation

gusty · 2022-11-18T18:51:40Z

src/FSharpPlus/Extensions/Validators.fs

+    open System
+    open FSharpPlus.Data
+
+    let inline validate error f v =


We have this function already and it's being deprecated.

wallymathieu · 2022-11-20T12:31:02Z

src/FSharpPlus/Extensions/Validators.fs

+        else
+            Failure [ error ]
+
+    let inline string error value =


I'm unsure if just calling it string makes it obvious. Would it be better to call it notNullOrWhiteSpace ?

wallymathieu · 2022-11-20T12:32:18Z

src/FSharpPlus/Extensions/Validators.fs

+
+        validate (error value) check value
+
+    let inline guid error value =


this type of validator goes into the question if there is some more general class of nonEmpty restrictions?

wallymathieu · 2022-11-20T16:45:30Z

There seems to be prior work that we can reuse some of the thoughts from. For dynamic languages we have:

https://clojure.org/about/spec
https://github.com/jquense/yup

While for F# we have

https://github.com/lfr/FSharp.Domain.Validation
https://github.com/JamesRandall/AccidentalFish.FSharp.Validation#built-in-validators

and the new library:

https://github.com/pimbrouwers/Validus#built-in-validators

Perhaps we can reuse some of the design work while being more in line with the vision that you promote in this PR (possible to write strictly typed validations instead of stringly typed validation keys/messages)?

wallymathieu · 2022-11-20T17:08:47Z

Some of the operators seems to not have stabilised in Validus yet. The different libraries all have their built in validators that we can look at. Seems like there is some polymorphism going on for some of the validators.

rodriguestiago0 added 3 commits November 14, 2022 21:12

Added computation expression for validation and added some extensions…

b8ca198

… methods

Revert change

8ea0b26

revert change

cedb1b2

rodriguestiago0 marked this pull request as draft November 14, 2022 21:34

gusty reviewed Nov 14, 2022

View reviewed changes

xperiandri suggested changes Nov 15, 2022

View reviewed changes

Pr suggestions

3762d16

gusty reviewed Nov 15, 2022

View reviewed changes

tests/FSharpPlus.Tests/Validations.fs Show resolved Hide resolved

gusty reviewed Nov 15, 2022

View reviewed changes

tests/FSharpPlus.Tests/Validations.fs Outdated Show resolved Hide resolved

gusty reviewed Nov 16, 2022

View reviewed changes

src/FSharpPlus/Extensions/Validation.fs Outdated Show resolved Hide resolved

rodriguestiago0 and others added 5 commits November 16, 2022 10:36

added value to error

d997501

Merge branch 'fsprojects:master' into rodrigues/add-validation

42fc644

Merge branch 'rodrigues/add-validation' of https://github.com/rodrigu…

22e5f28

…estiago0/FSharpPlus into rodrigues/add-validation

added new methods

d6a9cec

Removed computation expression

0a69dc5

rodriguestiago0 changed the title ~~Added computation expression for validation and added some extensions methods~~ Added some extensions methods for validation Nov 18, 2022

gusty reviewed Nov 18, 2022

View reviewed changes

wallymathieu reviewed Nov 20, 2022

View reviewed changes

Rename some functions

9868e74

gusty force-pushed the master branch 2 times, most recently from 5b61ffc to ad56a34 Compare December 2, 2022 10:55

wallymathieu force-pushed the master branch from a473313 to 94a2c99 Compare December 3, 2022 07:14

gusty force-pushed the master branch 3 times, most recently from 61dfe6f to 67d1b75 Compare February 21, 2023 13:58

gusty force-pushed the master branch 7 times, most recently from 105ed2c to d80a4ad Compare February 22, 2023 07:56

wallymathieu force-pushed the master branch 5 times, most recently from f92d910 to 39638fb Compare February 22, 2023 17:36

gusty force-pushed the master branch 6 times, most recently from 9b34ece to b2f3c8c Compare October 15, 2023 05:01

gusty force-pushed the master branch 2 times, most recently from 484cff5 to 142c806 Compare December 18, 2023 08:18

gusty force-pushed the master branch from 2e2f432 to 88fd94c Compare January 13, 2024 07:46

fcallejon changed the title ~~Added some extensions methods for validation~~ Add some extensions methods for validation Jun 9, 2024

gusty force-pushed the master branch 6 times, most recently from eef4e98 to f2e49ba Compare September 18, 2024 07:45

wallymathieu force-pushed the master branch from 93cda1e to ac40d3e Compare January 11, 2026 10:01

gusty force-pushed the master branch from ac40d3e to 25fb57f Compare January 11, 2026 17:53


		validate (error value) check value

		let inline guid error value =

Conversation

rodriguestiago0 commented Nov 14, 2022

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

gusty commented Nov 15, 2022

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

wallymathieu commented Nov 20, 2022 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

wallymathieu commented Nov 20, 2022

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

wallymathieu commented Nov 20, 2022 •

edited

Loading