I want to make where clause of LINQ query dynamic

Question

I want to make where class dynamic. When someone will call this function then I don't know the total numbers of parameters and comparison operator(e.g equalto, greaterthen etc) and field-names as well.How can I achieve this?

In this example I am using three parameters. "PartitionKey","RowKey" and tableName.It may be 0 or any numbers and Also it can be any like "FirtName", "Age" etc

public void Persons(string whereClauseParameters)
{            
    var query = (from p in cloudTable.CreateQuery<CustomTableEntity>()
                  where p.PartitionKey == "" && p.RowKey != "" && p.TableName == ""
                  select p);
}

possible duplicate of [Dynamic WHERE clause in LINQ](http://stackoverflow.com/questions/848415/dynamic-where-clause-in-linq) — GSerg, Aug 27 '15 at 12:53
possible duplicate of [Dynamic where clause in LINQ?](http://stackoverflow.com/questions/17789472/dynamic-where-clause-in-linq) — Tim Rogers, Aug 27 '15 at 12:53

score 0 · Answer 1 · answered Aug 27 '15 at 12:52

It sounds you're looking for something like Dynamic Linq. This allows you to do queries like:

var query = northwind.Products
                         .Where("CategoryID = 3 AND UnitPrice > 3")
                         .OrderBy("SupplierID");

where the fields can be specified as dynamic strings, instead of 'hard-coded'.

score 0 · Answer 2 · answered Aug 27 '15 at 12:53

0

Something like this?

public void Persons(Predicate<Person> pred)
{
    var query = from p in cloudTable.CreateQuery<CustomTableEntity>()
                where pred(p)
                select p;
}

answered Aug 27 '15 at 12:53

dcastro

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Still needs to hardcore the `pred` – FindOutIslamNow Apr 12 '18 at 06:19

score 0 · Answer 3 · answered Aug 27 '15 at 12:57

You can add conditions to a query dynamically. Example:

public void Persons(string firstName, string lastName, int? age) {            

  var query = loudTable.CreateQuery<CustomTableEntity>();

  if (firstName != null) {
    query = query.Where(p => p.FirstName == firstName);
  }

  if (lastName != null) {
    query = query.Where(p => p.LastName == lastName);
  }

  if (age.HasValue) {
    query = query.Where(p => p.Age == age.Value);
  }

  // then use the query

}

I want to make where clause of LINQ query dynamic

3 Answers3