Dynamic where clause in LINQ?

Question

I am trying to load data based on Dynamic where condition. ``` string tempQry = string.Empty; if (!string.IsNullOrEmpty(cusid) && !string.IsNullOrEmpty(mktid)) tempQry = "x=>x.MarketID==" + mktid + "&& x.MasterCustomerID==" + cusid; if (string.IsNullOrEmpty(cusid)) tempQry = "x=>x.MarketID==" + mktid; if (string.IsNullOrEmpty(mktid)) tempQry = "x=>x.MasterCustomerID==" + cusid; _lstOptInInterest = new LinkedList( (from a in _lstOptInInterest join b in _marketoEntities.CustCommPreferences.Where(tempQry) on new { CODE = a.Code, SUBCODE = a.SubCode } equals new { CODE = b.Option_Short_Name, SUBCODE = b.Option_Short_Subname } into leftGroup from b in leftGroup.DefaultIfEmpty() select new OptInInterestArea() { Code = a.Code, SubCode = a.SubCode, SubCodeDescription = a.SubCodeDescription, CodeDescription = a.CodeDescription, PrevOptIn = b != null && b.OptedIn == true }).ToList()); ``` It is giving compilation error `Where(tempQry)`. ` 'System.Data.Entity.DbSet

Accepted Answer

`Where` awaits conditions in form of lambdas rather than strings, so you have to refactor your code a little bit (just an idea below):

```
IQueryable<CustCommPreference> query = _marketoEntities.CustCommPreferences.AsQueryable();
if (!string.IsNullOrEmpty(cusid)) 
    query = query.Where(x => x.MasterCustomerID == cusid);
if (!string.IsNullOrEmpty(mktid)) 
    query = query.Where(x => x.MarketID == mktid);
```

and later use it:

```
...
join b in query
...
```

Dynamic where clause in LINQ?

Solution

Problem