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

Question

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

I have a search form that looks like this:

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.

Answer 1

Have you looked into using Lucene.NET for this project? given the nature of your searches it would be very simple to build that using Lucene, as it allows you to combine filters on different columns just like your requirements

Answer 2

You can build expression tree for where predicate using code. For example,

public static IQueryable<T> DynamicWhere<T>(this IQueryable<T> src, string propertyName, string value)
{
    var pe = Expression.Parameter(typeof(T), "t");
    var left = Expression.Property(pe, typeof(T).GetProperty(propertyName));
    var right = Expression.Constant(value);
    // Illustrated a equality condition but you can put a switch based on some parameter
    // to have different operators
    var condition = Expression.Equal(left, right);

    var predicate = Expression.Lambda<Func<T, bool>>(condition, pe);
    return src.Where(predicate);
}

Use it as Orders.DynamicWhere(searchBy, searchValue). You can add one more parameter to accept the operator such as Equals, Greater Than etc to complete the function.

See these links for more info:

http://msdn.microsoft.com/en-us/library/bb882637.aspx

http://msdn.microsoft.com/en-us/library/bb397951.aspx

Also check list of methods on the Expression class to get an idea.

Answer 3

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.

Answer 4

create method and call it on button click demo below

public List gettaskssdata(int c, int userid, string a, string StartDate, string EndDate, string ProjectID, string statusid) {

        List<tbltask> tbtask = new List<tbltask>();


        var selectproject = entity.tbluserprojects.Where(x => x.user_id == userid).Select(x => x.Projectid);

        if (statusid != "" && ProjectID != "" && a != "" && StartDate != "" && EndDate != "")
        {
            int pid = Convert.ToInt32(ProjectID);
            int sid = Convert.ToInt32(statusid);
            DateTime sdate = Convert.ToDateTime(StartDate).Date;
            DateTime edate = Convert.ToDateTime(EndDate).Date;
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblproject.ProjectId == pid) && (x.tblstatu.StatusId == sid) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a)) && (x.StartDate >= sdate && x.EndDate <= edate)).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if (statusid == "" && ProjectID != "" && a != "" && StartDate != "" && EndDate != "")
        {
            int pid = Convert.ToInt32(ProjectID);
            DateTime sdate = Convert.ToDateTime(StartDate).Date;
            DateTime edate = Convert.ToDateTime(EndDate).Date;
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblproject.ProjectId == pid) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a)) && (x.StartDate >= sdate && x.EndDate <= edate)).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if (ProjectID == "" && statusid != "" && a != "" && StartDate != "" && EndDate != "")
        {
            int sid = Convert.ToInt32(statusid);
            DateTime sdate = Convert.ToDateTime(StartDate).Date;
            DateTime edate = Convert.ToDateTime(EndDate).Date;
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblstatu.StatusId == sid) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a)) && (x.StartDate >= sdate && x.EndDate <= edate)).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if(ProjectID!="" && StartDate == "" && EndDate == "" && statusid == ""  && a == "")
        {
            int pid = Convert.ToInt32(ProjectID);
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblproject.ProjectId == pid)).OrderByDescending(x => x.ProjectId).ToList();

        }
        else if(statusid!="" && ProjectID=="" && StartDate == "" && EndDate == ""  && a == "")
        {
            int sid = Convert.ToInt32(statusid);
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblstatu.StatusId == sid) ).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if (a == "" && StartDate != "" && EndDate != "" && ProjectID != "")
        {
            int pid = Convert.ToInt32(ProjectID);
            DateTime sdate = Convert.ToDateTime(StartDate).Date;
            DateTime edate = Convert.ToDateTime(EndDate).Date;
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.ProjectId == pid) && (x.StartDate >= sdate && x.EndDate <= edate)).OrderByDescending(x => x.ProjectId).ToList();

        }
        else if (StartDate == "" && EndDate == "" && statusid != "" && ProjectID != "" && a != "")
        {
            int pid = Convert.ToInt32(ProjectID);
            int sid = Convert.ToInt32(statusid);
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblproject.ProjectId == pid) && (x.tblstatu.StatusId == sid) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a))).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if (a == "" && StartDate == "" && EndDate == "" && ProjectID != "" && statusid != "")
        {
            int pid = Convert.ToInt32(ProjectID);
            int sid = Convert.ToInt32(statusid);
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Include(x => x.tblstatu).Where(x => selectproject.Contains(x.ProjectId) && x.tblproject.company_id == c && x.tblproject.ProjectId == pid && x.tblstatu.StatusId == sid).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if (a != "" && StartDate == "" && EndDate == "" && ProjectID == "" && statusid == "")
        {
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a))).OrderByDescending(x => x.ProjectId).ToList();

        }
        else if (a != "" && ProjectID != "" && StartDate == "" && EndDate == "" && statusid == "")
        {
            int pid = Convert.ToInt32(ProjectID);
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.tblproject.ProjectId == pid) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a))).OrderByDescending(x => x.ProjectId).ToList();
        }
        else if (a != "" && StartDate != "" && EndDate != "" && ProjectID == "" && statusid == "")
        {
            DateTime sdate = Convert.ToDateTime(StartDate).Date;
            DateTime edate = Convert.ToDateTime(EndDate).Date;
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && (x.tblproject.company_id == c) && (x.TaskName.Contains(a) || x.tbUser.User_name.Contains(a)) && (x.StartDate >= sdate && x.EndDate <= edate)).OrderByDescending(x => x.ProjectId).ToList();
        }
        else
        {
            tbtask = entity.tbltasks.Include(x => x.tblproject).Include(x => x.tbUser).Where(x => selectproject.Contains(x.ProjectId) && x.tblproject.company_id == c).OrderByDescending(x => x.ProjectId).ToList();
        }
        return tbtask;

    }

Answer 5

We started out resolving similar queries against our Entity Framework model using dynamic linq queries. However, our attempts to generalize query generation resulted in bad performance due to EF being confused by the resulting complex expressions, so in the end horrible SQL was produced.

We resorted to Entity SQL.

Answer 6

Not sure if you are using MS SQL. Seems SQL could do most of the work for you, and you can build dynamic queries. Obviously the select/from statement needs work, but you can get the idea from the where clause.

DECLARE @SEARCHTYPE VARCHAR(20)
DECLARE @SEARCHTERM VARCHAR(100)

SELECT
    [FIELDS]
FROM
    [TABLE]
WHERE
    (@SEARCHTYPE = 'BEGINSWITH' AND [FIELD] LIKE @SEARCHTERM + '%') OR
    (@SEARCHTYPE = 'ENDSWITH' AND [FIELD] LIKE '%' + @SEARCHTERM) OR
    (@SEARCHTYPE = 'EQUALS' AND [FIELD] = @SEARCHTERM)

Answer 7

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));