Dynamic Where in linq with list parameters in action asp.net mvc

Question

I'm working on a screen where I'm displaying the list of products but when the user clicks on different checkboxes, I got the value of checked checkboxes value in action parameter. Here is my screen.

Product Screen

Now what I want to request the query dynamically on different items selection.

   public async Task<IEnumerable<Product>> GetSpecificProducts
        (List<int> brands, List<int> categories, List<int> sugar)
    {
        var products = await _context.Products
            .Where(x => x.BrandId == ???)
            .Where(x => x.CategoryId == ???)
            .Where(x => x.Sugar == ???)
            .ToListAsync();
    }`

I've already take a look on some stackoverflow questions but I'm just getting results in case of single value like here. How can I generate the dynamic linq on multiple where clauses.

One more thing please, sugar is my boolean property how can I deal with it, prntscr.com/jxxt0e — Usama Shahid
– Usama Shahid, Commented Jun 22, 2018 at 8:08
@UsamaShahid so why did you pass a List<int> sugar if Sugar is a boolean property? Instead of List<int> sugar it should be bool sugar in your parameters method. — CodeNotFound
– CodeNotFound, Commented Jun 22, 2018 at 8:12

CodeNotFound · Accepted Answer · 2018-06-22 12:28:39Z

3

You just need to check that each collection is not empty before including it as a filter of your query like below:

public async Task<IEnumerable<Product>> GetSpecificProducts 
     (List<int> brands, List<int> categories, bool? sugar)
{
    IQueryable<Product> query = _context.Products;

    if(brands != null && brands.Any()) 
        query = query.Where(x => brands.Contains(x.BrandId));

    if(categories != null && categories.Any()) 
        query = query.Where(x => categories.Contains(x.CategoryId));

    if(sugar.HasValue) 
        query = query.Where(x => x.Sugar == sugar);

    var products = await query.ToListAsync();
}

edited Jun 22, 2018 at 12:28

answered Jun 22, 2018 at 7:58

CodeNotFound

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13 Comments

Usama Shahid Over a year ago

One more thing please, sugar is my boolean property in the database. I'm setting the values against sugar and non sugar in this way, prnt.sc/jxxt0e. Would you please guide me what can I do it in this scenario.

CodeNotFound Over a year ago

@UsamaShahid I edited my answer below. You should pass sugar as a bool? and set its value only when the user selected it.

CodeNotFound Over a year ago

@UsamaShahid and when the user selects Sugar and NonSugar you let the value null

CodeNotFound Over a year ago

@UsamaShahid I haven't access to this page. It is blocked :) Can you add the error as a comment please.

Usama Shahid Over a year ago

Ooops! it was my mistake. I was missing to assign it again in query variable. query = query.Where(x => x.Sugar == sugar) Thank you so much @CodeNotFound

|

Amit · Accepted Answer · 2018-06-22 08:34:58Z

when you want a list of Product where it's brandId is in the list of brands, categoryId is in list of categorise and sugar is in list of sugar, you can do it like.

public async Task<IEnumerable<Product>> GetSpecificProducts
    (List<int> brands, List<int> categories, List<int> sugar)
{
    var products = await _context.Products
        .Where(x => brands.Contains(x.BrandId) &&
                    categories.Contains(x.CategoryId) &&
                    sugar.Contains(x.Sugar))
        .ToListAsync();
}

----------Update----------

as you have mentioned that sugar is bool property in your database, and as you are already suggested you can change your method's signature.

Also updating my code to check emptyness of lists, if lists are empty that means user has not selected any filter and thus we will ignore that criteria in filtering.

public async Task<IEnumerable<Product>> GetSpecificProducts
    (List<int> brands, List<int> categories, bool? sugar)
{
    var products = await _context.Products
        .Where(x => (brands.Any() ? brands.Contains(x.BrandId) : true) &&
                    (categories.Any() ? categories.Contains(x.CategoryId) : true) &&
                    (sugar.HasValue ? sugar == x.Sugar : true))
        .ToListAsync();
}

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