How to validate Selected Images using IValidatable

Sujeet Raman

3y927C#

I have a list of object and i need to save those objects with some details.I need to validate those image files using IValidatable

I am stuck on some point any help will appreciated thanks!

//in class one
public void submit button(){
foreach (var imageFile in ImageList)
{
await using var file = imageFile.File.OpenReadStream(MaxUploadFileSize)
    var ObjToDB = objclass .ToDB();

}

}

//in class two
public class objclass : IValidatableObject
{
    public IEnumerable Validate(ValidationContext validationContext)
    {
        //1.need to check the content type

        //2.need to check the name is there

        //3.need to check the list is empty or not


    }
    public string Name { get; set; }
    public string FileContentType { get; set; } //FileContentType how to validate for MIME types using ivalidatable

    public modelclass ToDB()
    {

        return new()
        {
            Name = Name,
            ContentType = FileContentType,

        };
    }
}

2 Replies

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Sujeet Raman3y ago

Validation is not working for below code.Almost i followed the same structure

[Required]
public string FileContentType { get; set; }

public IEnumerable Validate(ValidationContext validationContext)
{

    // Define a list of allowed MIME types
    var allowedMimeTypes = new[] { "image/jpeg", "image/png" };

    if (BrowsedfilesList != null)
    {
        foreach (var media in BrowsedfilesList)
        {
            // Check the MIME type of the file
            var file = media;
            FileContentType = file.ContentType;

            // If the MIME type is not in the list of allowed MIME types, return a validation error
            if (!allowedMimeTypes.Contains(FileContentType))
            {
                yield return new ValidationResult($"File {file.FileNameWithoutExtension} has invalid MIME type {FileContentType}.");
            }
            //If file name is not given
            if (string.IsNullOrEmpty(file.FileNameWithoutExtension))
            {
                yield return new ValidationResult("File name is required.", new[] { nameof(file.FileNameWithoutExtension) });
            }

        }
    }
}

Anupam Maiti3y ago

You can try out like below.

public class MyObject : IValidatable
{
    public IFormFile Image { get; set; }

    public IEnumerable Validate(ValidationContext validationContext)
    {
        var results = new List();

        if (Image == null)
        {
            results.Add(new ValidationResult("Image is required."));
        }
        else
        {
            // Validate image file
            if (!Image.ContentType.StartsWith("image"))
            {
                results.Add(new ValidationResult("Invalid image file type."));
            }
            if (Image.Length > 5000000)
            {
                results.Add(new ValidationResult("Image file size must be less than 5MB."));
            }
        }
        return results;
    }
}

NOTE : The FileContentType property returns the value of the Content-Type header of the uploaded file, which is usually in the format image/jpeg, image/png, etc. You can compare this value with a list of allowed MIME types to validate the file.