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How to implement search functionality in C#/ASP.NET MVC

Asked 2011-08-29T00:26:46.493
11

I am developing an ASP.NET MVC 3 application using C# and Razor.

I have a search form that looks like this: searchform

The search form works in the following way:

  1. The user selects which property they want to search on.
  2. The user selects how they want to match the search string (e.g. contains, starts with, ends with, equals, etc).
  3. The user enters a search term and clicks Search.

The selections in the first drop down related directly to a property in my ADO.NET Entity Framework model class (and therefore directly to a table column).

Users need the ability to explicitly select which property and which matching method when searching, e.g. a user will explicitly search for all matches of process number that equals '132'.

My first approach was to use dynamic linq to construct a Where clause from the search criteria (see my original question). However I'm starting to think that this isn't the best way to do it.

I'm also hoping for a solution that doesn't require me to hard code the result for each property + matching criteria combination.

Any suggestions on how I should implement this search? It doesn't have to be using my current search form, totally open to any other ideas that fit the requirements.

c# .net asp.net-mvc search
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2 Answers

1

You can use Dynamic Linq and you can create the Where clausole with a utility class like this:

public class Criteria 
{
   StringBuilder sb = new StringBuilder();
   bool first = true;

   public void And(string property, string dbOperator, string value) {
       if (first)
       {
           sb.Append(" ").Append(property).Append(" ");
           sb.Append(" ").Append(dbOperator).Append(" ");
           sb.Append(" ").Append(value).Append(" ");
           first = false;
       }
       else
       {
           sb.Append(" && ").Append(property).Append(" ");
           sb.Append(" ").Append(dbOperator).Append(" ");
           sb.Append(" ").Append(value).Append(" ");
       }
   }

   public void Or(string property, string dbOperator, string value)
   {
       if (first)
       {
           sb.Append(" ").Append(property).Append(" ");
           sb.Append(" ").Append(dbOperator).Append(" ");
           sb.Append(" ").Append(value).Append(" ");
           first = false;
       }
       else
       {
           sb.Append(" || ").Append(property).Append(" ");
           sb.Append(" ").Append(dbOperator).Append(" ");
           sb.Append(" ").Append(value).Append(" ");
       }
   }

   public string ToString() 
   {
       return sb.ToString();
   }

}

So you can build a Criteria with many properties using Or or And methods and put it in the Where operator of Dynamic Linq.

answered 2011-09-16T07:02:48.670
0

You could have the first combo data source set to myEntityObject.GetType().GetProperties(), the second to a list of displayable Funcs<string, string, bool>, like this:

public class ComboPredicate
{
    public Func<string, string, bool> Func {get; set;}
    public string Name {get; set; }
}

Later, when you load the form:

comboProperty.Datasource = myEntityObject.GetType().GetProperties()
comboOperation.Datasource = new List<Predicate>
    {
        {
            Name = "Contains",
            Predicate = (s1, s2) => s1 != null && s1.Contains(s2),
        },
        {
            Name = "Equals",
            Predicate = (s1, s2) => string.Compare(s1, s2) == 0,
        },
        //...
    }

And later, when you want to select your entities:

var propertyInfo = (PropertyInfo)comboProperty.SelectedValue;
var predicate = ((ComboPredicate)comboOperation.SelectedValue).Predicate;
var filteredObjects = objects.Where(o => predicate(propertyInfo.GetValue(o, null).ToString(), textBoxValue.Text));
answered 2011-09-21T15:16:38.937

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