How to return dynamic object from SQL query

问题

I have situation where a storeprocdure return collection, but I do not how the object structure because the query is very dynamic.

One query can return:

Id | Location | MarketSegment | ... n columns

and another can return

Id | Sales Rep | Location | Region | ... n columns

I am simply just return a "object" as you can see in the code below. I know this won't work, but how can I set it up so it does?

using (DbContext db = new Context())
{

    var items = db.Database.SqlQuery<object>(
        "SP @Param1, @Param2",
        new SqlParameter("Param1", ped),
        new SqlParameter("Param2", 25)
    ).ToList();

    return Request.CreateResponse<List<object>>(HttpStatusCode.OK, items);
}

EDIT:

I don't know if showing the SP will help in anyways, except if I can explain it more.

Each columns are represented as Custom Fields. Users are able to create n numbers of Custom Fields. So If you run the SP for User1 and he has 5 custom fields, then each custom fields will be represented in Columns, but If User2 has 3 custom fields, only 3 columns will be represented. What I don't have control over is the Custom Field Name and number of custom fields.

回答1:

You can't use SqlQuery<T> for custom fields.

Creates a raw SQL query that will return elements of the given generic type. The type can be any type that has properties that match the names of the columns returned from the query, or can be a simple primitive type. - MSDN

But, you can use ExecuteReader to achieve that.

using (var db = new Context())
{
    db.Database.Connection.Open();

    var cmd = db.Database.Connection.CreateCommand();
    cmd.CommandText = "SP @Param1, @Param2";
    cmd.Parameters.Add(new SqlParameter("Param1", ped));
    cmd.Parameters.Add(new SqlParameter("Param2", 25));

    List<List<object>> items = new List<List<object>>();
    var reader = cmd.ExecuteReader();
    while (reader.Read())
    {
        var item = new List<Object>();
        items.Add(item);

        for (int i = 0; i < reader.FieldCount ; i++)
            item.Add(reader[i]);
    }

    return Request.CreateResponse<List<object>>(HttpStatusCode.OK, items);
}

回答2:

If you know what all the possible columns could be returned, there is no issue with using a class that has more properties than you need.

public class Data
{
public int ID {get;set;}
public string SalesRep {get;set;}//Simply will be empty in the first example, but populated in the second.
public string Location {get;set;}
}

回答3:

If on SQL 2016 or newer, add "FOR JSON AUTO" to your query to return as JSON, e.g:

var json = db.Database.SqlQuery<string>("Select x, y, z FROM tbl FOR JSON AUTO").First();

Then use Json.Net to create a dynamic object using

var myDynamic = JObject.Parse(json)

来源：https://stackoverflow.com/questions/25494384/how-to-return-dynamic-object-from-sql-query

标签

sql

entity-framework

asp.net-web-api

dbcontext