c# - Dynamically add filter to Linq queryable which calls a DataContext method -

i having trouble creating expression add queryable filter condition. replicate following:

starting simple queryable:

iqueryable<customer> query = customer in context.customer     select customer; 

i dynamically add filter condition involves calling method on datacontext:

iqueryable<customer> query = customer in context.customer     customer.name == context.convertvalueforsearch(searchstring)     select customer; 

so 'convertvalueforsearch' calls appropriate database function when evaluated.

the above produces following sql:

exec sp_executesql n'select [t0].[custname]    [dbo].[customer] [t0]    [t0].[custname] = [dbo].[fnconvertsearchstringvalue](@p0)',n'@p0 varchar(8000)',@p0='foo' 

we have number of datacontext derived types, convertvalueforsearch defined through interface (isearchvalueconverter) each of our datacontext types implement.

i not sure how correctly create expression call convertvalueforsearch(string searchvalue) on datacontext , create final expression.equal made of property accessor customer.name , method call convertvalueforsearch filter can applied queryable createquery.

if start following:

... code executed in repository instance <func<manager<tentity, trootdal, tuniqueidentifiertype>, string, string>> convertsearchstringvaluelambda =     (manager, searchvaluetoconvert) => manager.datacontextforconversionforspecificcontext.convertvalueforsearch(searchvaluetoconvert); var invokedcall = expression.invoke(convertsearchstringvaluelambda, expression.constant(this), expression.constant(searchvalue));  ...code executed in filter item instance apply filter queryable // accessor customer.name     lambdaexpression propertyaccessor = entity<tdalentity>.getpropertyaccessorexpression<string>(this.filterfield); binaryexpression filterexpression = expression.equal(propertyaccessor.body, filtervalue);  expression filter = expression.lambda(filterexpression, propertyaccessor.parameters);  query = query.provider.createquery<tdalentity>(     expression.call(         typeof(queryable),         "where",         new type[] { query.elementtype },         query.expression,         filter)); 

the call fnconvertsearchstringvalue done in separate call db , results of passed database when queryable used. although might ok in circumstances, need function called in sql generated linq-to-sql above.

thank suggestions.