CODEWITHSUNDEEP
.netvb.netentity-frameworkobjectquery
Dane
Dane

Reputation: 629

Optional Where clause in query

I have an application that does a search of our database (exposed via EF) for records meeting certain conditions. We have two main tables (Jobs and Recipients). Recipients are linked to the Jobs table by a Job ID.

The job record has various fields (Process Date, Name, JobType). The recipient has a lot of Name and ID fields (e.g. Account Number, Surname, etc)

I want to present a search screen where they see a list of fields to search on. The ASP.net code then sees which textboxes the user typed in (or selected), and builds a query based on that.

I'm just trying to find the most efficient way possible.

The rough logic is : 

    if not string.isnullorempty(txtName.text) then
        'Query.Where.Add clause = " AND Name like '@txtName'
        'Query.WhereParameters.Add("@txtName",txtNAme.text
    end if

if not string.isnullorempty(txtAccountNumber.text) then 

.....etc


 if not string.isnullorempty(txtFromDate.text) then..

Where I'm stuck is figuring out how to add in additional where clauses. Should I just use Entity SQL?

Can this return strongly typed EF objects as well? And is it possible to return both the Jobs and Recipients objects?

e.g. if I did a select recipient., jobs. from....blah would this parse correctly and return linked Recipient and Job objects?

Upvotes: 0

Views: 342

Answers (1)

user743382
user743382

Reputation:

If you start from a strongly-typed unfiltered query, you can add filters using Queryable.Where.

Name = txtName.Text
If Not String.IsNullOrEmpty(Name) Then
    Query = Query.Where(Function(j) j.Name.Contains(Name))
End If

If your unfiltered query correctly links multiple records, those links will be preserved when you add a filter.

(Disclaimer: I don't usually use VB.NET; there may be silly syntax errors, but you should be able to get the general idea.)

Upvotes: 2

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