EF Core Extension Where Method Not Working

Question

I created new IQueryable extension method for my filter queries. In the extension method content added to my query manually, it is working. But its not working on the IQueryable extension method. How that happens ?

My Extension IQueryables :

 public static IQueryable<TSource> WhereIf<TSource>(this IQueryable<TSource> source, bool condition, Expression<Func<TSource, bool>> predicate)
    {
        if (condition)
            return source.Where(predicate);
        else
            return source;
    }


    public static IQueryable<ProductPrice> GetDynamicWhere(this IQueryable<ProductPrice> source,List<ProductFilterModel> productFilters)
    {
        Func<string, object> GetValue = (string key) => productFilters.Where(y => y.key == key).Select(x => x.value).FirstOrDefault();

        var minPrice = GetValue("min-price");
        var maxPrice = GetValue("max-price");

        source.Where(x=>x.IsDeleted==false)
              .WhereIf(minPrice != null, x => x.ProductVariant.ProductPrices.Where(y => y.IsDeleted == false).Select(y => y.Price).FirstOrDefault() >= Convert.ToInt32(minPrice.ToString()))
              .WhereIf(maxPrice != null, x => x.ProductVariant.ProductPrices.Where(y => y.IsDeleted == false).Select(y => y.Price).FirstOrDefault() <= Convert.ToInt32(minPrice.ToString()));

        return source;
    }

not working,this query returned all data:

MyDbContext.ProductPrices
           //.AsQueryable()
           .GetDynamicWhere(filter)
           .Include(x => x.ProductVariant.Product)
           .Include(x => x.ProductVariant.Variant)
           .Include(x => x.ProductVariant.Variant.VariantType)
           .ToList();

But this is working (same code in the GetDynamicWhere extension method) :

 MyDbContext.ProductPrices
            .Where(x=>x.IsDeleted==false)
            .WhereIf(minPrice != null, x => x.ProductVariant.ProductPrices.Where(y => y.IsDeleted == false).Select(y => y.Price).FirstOrDefault() >= Convert.ToInt32(minPrice.ToString()))
            .WhereIf(maxPrice != null, x => x.ProductVariant.ProductPrices.Where(y => y.IsDeleted == false).Select(y => y.Price).FirstOrDefault() <= Convert.ToInt32(minPrice.ToString()))
            .ToList();

You are not assigning back to source in your method `GetDynamicWhere` — Silvermind, Oct 25 '19 at 22:42

score 1 · Accepted Answer · answered Oct 25 '19 at 22:54

The Where and WhereIf clauses are not changing sources, but returning an IQueryable. You are not doing anything with that value and it's being thrown away. Then later, you return the original source.

Instead, you can do this:

return source.Where(x=>x.IsDeleted==false)
          .WhereIf(minPrice != null, x => x.ProductVariant.ProductPrices.Where(y => y.IsDeleted == false).Select(y => y.Price).FirstOrDefault() >= Convert.ToInt32(minPrice.ToString()))
          .WhereIf(maxPrice != null, x => x.ProductVariant.ProductPrices.Where(y => y.IsDeleted == false).Select(y => y.Price).FirstOrDefault() <= Convert.ToInt32(minPrice.ToString()));

EF Core Extension Where Method Not Working

1 Answers1