Question

I’ve been scouring the internet and every example I’ve found so far uses the same sort of a query to perform a search. I find this the hello world version of a search. I’ve found a few that use an if statement to select between a few queries, but still lack any real power.

(from c in context.table
where c.contains(searchField)).toList());

The search is so simple that I can not come up with how I would develop a search query for the below screenshot. Checkbox groups should create OR/IN clauses and pretty much everything else is an AND

for instance, the users checks Sarasota, Venice enters a yearbuilt 1990 and selects bedrooms 1+ and enters a sale date range from 1/1/2000 and leaves the to fieldblank.

in plain old SQL this would be.
where city = 'sarasota' or city = 'Venice' AND yearbuilt = 1990 AND bedrooms >= 1 AND fromSaleDate >= 1/1/2000 AND toSaleDate = 12/31/9999

if I was using old school sql strings and ASP classic I would use a combination of hardcoded clauses and few ifs and for statements to dynamically build the query string myself.

I’m envisioning a searchViewModel (yet to be written) of somekind that passes the values in somehow. So I can’t include a code sample of that ViewModel. And the real kicker is the Property Features section. That will be a dynamic list of available property features, so hardcoding that as part of the query is not an option.

I think somehow this might be relevant but I’m not sure. filtering a list using LINQ

Please help me take a step in the right direction. Thanks

Update

Here is the query as executed in Profiler. I tweaked it to declare the variables so I could run it interactively, but the query itself is unaltered

declare @p__linq__0 as datetime
declare @p__linq__1 as datetime

set @p__linq__0='1989-01-01 00:00:00'
set @p__linq__1='1990-01-01 00:00:00'
SELECT TOP (10) 
[Project3].[STRAP] AS [STRAP], 
[Project3].[SITUS] AS [SITUS], 
[Project3].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
[Project3].[PROPERTY_USE] AS [PROPERTY_USE], 
[Project3].[SUBDIVISION] AS [SUBDIVISION], 
[Project3].[DSCR] AS [DSCR], 
[Project3].[LAND_AREA] AS [LAND_AREA], 
[Project3].[INCORPORATION] AS [INCORPORATION], 
[Project3].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
[Project3].[CENSUS] AS [CENSUS]
FROM ( SELECT [Project3].[STRAP] AS [STRAP], [Project3].[SITUS] AS [SITUS], [Project3].[MAILING_ADDRESS] AS [MAILING_ADDRESS], [Project3].[PROPERTY_USE] AS [PROPERTY_USE], [Project3].[SUBDIVISION] AS [SUBDIVISION], [Project3].[DSCR] AS [DSCR], [Project3].[LAND_AREA] AS [LAND_AREA], [Project3].[INCORPORATION] AS [INCORPORATION], [Project3].[SEC_TWP_RGE] AS [SEC_TWP_RGE], [Project3].[CENSUS] AS [CENSUS], row_number() OVER (ORDER BY [Project3].[STRAP] ASC) AS [row_number]
    FROM ( SELECT 
        [Distinct2].[STRAP] AS [STRAP], 
        [Distinct2].[SITUS] AS [SITUS], 
        [Distinct2].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
        [Distinct2].[PROPERTY_USE] AS [PROPERTY_USE], 
        [Distinct2].[SUBDIVISION] AS [SUBDIVISION], 
        [Distinct2].[DSCR] AS [DSCR], 
        [Distinct2].[LAND_AREA] AS [LAND_AREA], 
        [Distinct2].[INCORPORATION] AS [INCORPORATION], 
        [Distinct2].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
        [Distinct2].[CENSUS] AS [CENSUS]
        FROM ( SELECT DISTINCT 
            [Distinct1].[STRAP] AS [STRAP], 
            [Distinct1].[SITUS] AS [SITUS], 
            [Distinct1].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
            [Distinct1].[PROPERTY_USE] AS [PROPERTY_USE], 
            [Distinct1].[SUBDIVISION] AS [SUBDIVISION], 
            [Distinct1].[DSCR] AS [DSCR], 
            [Distinct1].[LAND_AREA] AS [LAND_AREA], 
            [Distinct1].[INCORPORATION] AS [INCORPORATION], 
            [Distinct1].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
            [Distinct1].[CENSUS] AS [CENSUS]
            FROM   (SELECT DISTINCT 
                [Extent1].[STRAP] AS [STRAP], 
                [Extent1].[SITUS] AS [SITUS], 
                [Extent1].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
                [Extent1].[PROPERTY_USE] AS [PROPERTY_USE], 
                [Extent1].[SUBDIVISION] AS [SUBDIVISION], 
                [Extent1].[DSCR] AS [DSCR], 
                [Extent1].[LAND_AREA] AS [LAND_AREA], 
                [Extent1].[INCORPORATION] AS [INCORPORATION], 
                [Extent1].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
                [Extent1].[CENSUS] AS [CENSUS]
                FROM  [dbo].[Properties] AS [Extent1]
                INNER JOIN [dbo].[Transfers] AS [Extent2] ON [Extent1].[STRAP] = [Extent2].[STRAP]
                WHERE  CAST( [Extent2].[TRANS_DATE] AS datetime2) >= @p__linq__0 ) AS [Distinct1]
            INNER JOIN [dbo].[Transfers] AS [Extent3] ON [Distinct1].[STRAP] = [Extent3].[STRAP]
            WHERE  CAST( [Extent3].[TRANS_DATE] AS datetime2) <= @p__linq__1
        )  AS [Distinct2]
    )  AS [Project3]
)  AS [Project3]
WHERE [Project3].[row_number] > 0

Update

 if (Model == null)
            {
                Model = new SearchViewModel();
            }

            TryUpdateModel(Model);

            Model.Locations = _service.GetLocations().Select(x => new SelectListItem { Text = x.Value, Value = x.Key }).ToList();


            var results = _service.GetProperties();

            if (Model.SelectedLocation != null)
                results = (from r in results
                           where r.SITUS.ToLower().Contains(Model.SelectedLocation.ToLower())
                           select r);



            if (Model.ParcelID != null)
                results = (from r in results
                           where r.STRAP.StartsWith(Model.ParcelID.Replace("-", "")) || r.STRAP.Equals(Model.ParcelID.Replace("-", ""))
                           select r);

            if (Model.SqftFrom != null)
                results = (from r in results
                           from b in r.Buildings
                           where b.GROSS_AREA >= Model.SqftFrom
                           select r).Distinct();

            if (Model.SqftTo != null)
                results = (from r in results
                           from b in r.Buildings
                           where b.GROSS_AREA <= Model.SqftTo
                           select r).Distinct();


            if (Model.Bedrooms != null)
                results = (from r in results
                           from b in r.Buildings
                           from s in b.StructuralElements
                           where s.VALUE == Model.Bedrooms && s.DSCR.ToLower() == "bedrooms"
                           select r).Distinct();

            if (Model.Bathrooms != null)
                results = (from r in results
                           from b in r.Buildings
                           from s in b.StructuralElements
                           where s.VALUE == Model.Bathrooms && s.CATEGORY == "BT"
                           select r).Distinct();

            if (Model.SaleAmountFrom != null)
                results = (from r in results
                           from t in r.Transfers
                           where t.AMOUNT >= Model.SaleAmountFrom
                           select r).Distinct();

            if (Model.SaleAmountTo != null)
                results = (from r in results
                           from t in r.Transfers
                           where t.AMOUNT <= Model.SaleAmountTo 
                           select r).Distinct();


            if (Model.SalesFrom != null)
                results = (from r in results
                           from t in r.Transfers
                           where t.TRANS_DATE >= Model.SalesFrom
                           select r).Distinct();

            if (Model.SalesTo != null)
                results = (from r in results
                           from t in r.Transfers
                           where t.TRANS_DATE <= Model.SalesTo
                           select r).Distinct();

            //if (Model.SalesTo != null)
            //    results = (from r in results
            //               from t in r.Transfers
            //               where t.TRANS_DATE <= Model.SalesTo
            //               select r).Distinct();


                results = results.OrderBy(x => x.STRAP);

                Model.SearchResults = results.ToPagedList(page ??1 , size ?? 10);

            if (Model.SearchResults.Count() == 1)
            {
                var strap = Model.SearchResults.FirstOrDefault().STRAP;

                return RedirectToRoute("Details", new { id = strap });
            }
            else
            {
                return View(Model);
            }

Answer 1

LINQ sources (IQueryable<T>) are composable, so you can do:

IQueryable<Parcel> query = ctx.Parcels;
if(location != null)
    query = query.Where(x => x.Location == location);
if(tennisCourt)
    query = query.Where(x => x.HasTennisCourt);
if(minSaleDate != null)
    query = query.Where(x => x.SaleDate >= minSaleDate.Value);
if(maxSaleDate != null)
    query = query.Where(x => x.SaleDate <= maxSaleDate.Value);

then finally you can do:

// first 50, plus a final one to display "more..." link
var page = query.Take(51).ToList();

or:

int count = query.Count();

And the trick is: it only executes the fully composed query – i.e. anything that either enumerates the query (foreach, ToList, etc), or aggregates the query (Count, Sum, etc)