I'm supposted to make IQueryable handle particular cases where:

1. s => s.Trusting == searchTrusting
2. s => s.Trusted == searchTrusted
3. s => s.Trusting == searchTrusting and s => s.Trusted == searchTrusted
4. other cases

How am I supposted to make IQueryable request that would specify those cases. I never used IQueryable before.

My associate adviced me to use:

var specialCases = IQueryable.
IQueryable.

His comment was: this approach only partially fix problem try to combine IQueryable and separate if for each case.

How can I achieve combining IQueryable?

Before his comment ifs were in state of if, else if, else if, else To get the same result, my existing solution used:(it works)

var domainTrustColl = _domainTrustRepository.GetDomainTrustItems().ToList().ConvertAll(new Converter<DomainTrustItem, DomainTrustModel>(DomainTrustModel.FromDomain));

domainTrustColl = domainTrustColl.Where(s => s.Trusting.Contains(searchTrusting)).Where(s => s.Trusted.Contains(searchTrusted)).Where(s => s.Type.Contains(searchType)).ToList();

            if (!string.IsNullOrEmpty(searchTrusting))
            {
                domainTrustColl = domainTrustColl.Where(s => s.Trusting == searchTrusting).Where(s => s.Trusted.Contains(searchTrusted)).Where(s => s.Type.Contains(searchType)).ToList();
            }
            if (!string.IsNullOrEmpty(searchTrusted))
            {
                domainTrustColl = domainTrustColl.Where(s => s.Trusting.Contains(searchTrusting)).Where(s => s.Trusted == searchTrusted).Where(s => s.Type.Contains(searchType)).ToList();
            }
            if (!string.IsNullOrEmpty(searchTrusting) && !string.IsNullOrEmpty(searchTrusted))
            {
                domainTrustColl = domainTrustColl.Where(s => s.Trusting == searchTrusting).Where(s => s.Trusted == searchTrusted).Where(s => s.Type.Contains(searchType)).ToList();
            }

CodePudding user response：

From your LINQ query, I saw it is redundant with this statement

.Where(s => s.Type.Contains(searchType))

Hence, your IQueryable query can be simplified as below:

...

var query = domainTrustColl.Where(s => s.Type.Contains(searchType));

// Case - Both not selected
if (string.IsNullOrEmpty(searchTrusting) && string.IsNullOrEmpty(searchTrusted))
{
    // Handle no select any case
}
// Third case - Both selected
else if (!string.IsNullOrEmpty(searchTrusting) && !string.IsNullOrEmpty(searchTrusted))
{
    query = query.Where(s => s.Trusting == searchTrusting)
        .Where(s => s.Trusted == searchTrusted);
}
// First case
else if (!string.IsNullOrEmpty(searchTrusting))
{
    query = query.Where(s => s.Trusting == searchTrusting)
        .Where(s => s.Trusted.Contains(searchTrusted));
}
// Second case
else if (!string.IsNullOrEmpty(searchTrusted))
{
    query = query.Where(s => s.Trusting.Contains(searchTrusting))
        .Where(s => s.Trusted == searchTrusted);
}

domainTrustColl  = query.ToList();

And lastly, materialize the query to execute the query via .ToList().