Access to Properties Dynamically in LINQ

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I have a table with almost 30 fields. I have used LINQ in order to access to my DB. In LINQ you can access to properties by writing a code like this: c.propertyname

What I want now to do is that I want to access the properties without knowing the property name at compile time. It means that the property name will be passed to at runtime, so it means that I want to access my property value by writing a code like c.X (in which X is a VARIABLE that its value will be determined during runtime and in a dynamic mode).

What can I do in order to that?
Thanks a lot in advance.

Posted 1-Nov-10 20:04pm

alijoongolgoli

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NMehta83 · Answer 1 · 2010-11-01T20:35:00

Solution 1

You have to make the query in your string builder and you have to replace it runtime like below example

C#

StringBuilder sb = new StringBuilder();
string runtimePropertyName = string.Empty;
string runtimePropertyValue = string.Empty;
sb.Append("from a in db.abc where a.#PropertyName#==#PropertyValue# select a.ToList();");
sb.Replace("#PropertyName#", runtimePropertyName);
sb.Replace("#PropertyValue#", runtimePropertyValue);
var list = sb.ToString();

If this helped you then please Vote and accept as Answer. :rose:

Posted 1-Nov-10 20:35pm

NMehta83

Comments

Hiren solanki 2-Nov-10 3:10am

are you sure it will run ?

Dalek Dave 2-Nov-10 4:22am

Good Answer.

Xmindz 13-Mar-12 1:43am

Did this one work?

Xmindz 13-Mar-12 1:46am

Can we do something similar with the LINQ predicates? Like .OrderBy(x=> x.PropertyName)
Can I change the PropertyName dynamically here?

alijoongolgoli · Answer 2 · 2010-11-01T21:13:00

Solution 2

thanks for your answer. it seems that will work. but after making the query, what can i do in order to put the string that has been built as the datasourse of a (for example) dropdownlist. you know that you can not put a string as the datasourse. so what is the conversion that is needed

Posted 1-Nov-10 21:13pm

alijoongolgoli

NMehta83 · Answer 3 · 2010-11-01T22:43:00

How to build LINQ Queries at Runtime in C#

http://tomasp.net/blog/dynamic-linq-queries.aspx[^]

You can use the dictionary class for that add key-value pair into it and bind as the datasource to your dropdown list like

C#

Dictionary<string, string> dict = new Dictionary<string, string>();
dict.Add("sb", list);
DropDownList dl = new DropDownList();
dl.DataSource = dict;