How to handle Null array in Linq

Question

I have a methods that takes multiple arrays and filter data using linq, the problem I am having is that one or more arrays could be null and I am not sure how to handle null arrays in Linq.:

public IPagedList<SGProduct> GetFilteredProducts(string catID, string[] houseID, int page = 1)
        {
            return MongoContext.Products.AsQueryable<SGProduct>().AsEnumerable().Where(x =>houseID.Contains(x.HouseID.ToString()) && x.ProductCategoryID.ToString() == catID).ToList().ToPagedList(page, 6);
        }

The houseID array could be null also I will have more parameters to this method like Size array etc.

Any suggestions. Thanks

Mantas Čekanauskas · Accepted Answer · 2017-03-30 11:04:02Z

1

Just add null check for array, end create empty one if it's null.

public IPagedList<SGProduct> GetFilteredProducts(string catID, string[] houseID, int page = 1)
{
    if(houseID == null) houseID = new string[] {};
    return MongoContext.Products.AsQueryable<SGProduct>().AsEnumerable().Where(x =>houseID.Contains(x.HouseID.ToString()) && x.ProductCategoryID.ToString() == catID).ToList().ToPagedList(page, 6);
}

Also, you can query variable and build it with conditions as you go. And then you have finished, just materialize and return records.

public IPagedList<SGProduct> GetFilteredProducts(string catID, string[] houseID, int page = 1)
{
    var query = MongoContext.Products.AsQueryable<SGProduct>();
    if(houseID == null)
        query = query.Where(x =>houseID.Contains(x.HouseID.ToString()) && x.ProductCategoryID.ToString() == catID);

    return query.ToList().ToPagedList(page, 6);
}

edited Mar 30, 2017 at 11:04

answered Mar 30, 2017 at 10:57

Mantas Čekanauskas

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