CODEWITHSUNDEEP
c#linq
programmer
programmer

Reputation: 1094

C# How to declare new Dictionary object based off a string array within a LINQ query

I have some code like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;

class Program
{
    static void Main(string[] args)
    {
        string xml = @"<Root>
  <Report1>
    <Row>
      <Field1>data1-1</Field1>
      <Field2>data1-2</Field2>
      <!-- many more fields -->
    </Row>
    <Row>
      <Field1>data2-1</Field1>
      <Field2>data2-2</Field2>
      <!-- many more fields -->
    </Row>
  </Report1>
</Root>";

        XDocument doc = XDocument.Parse(xml);

        var report1 = from report in doc.Root.Elements("Report1").Elements("Row")
                      select new Dictionary<string, string>()
                          {
                              {"Field1", report.Elements("Field1").First().Value},
                              {"Field2", report.Elements("Field2").First().Value}
                          };

        var i = 1;
        foreach (Dictionary<string, string> dict in report1)
        {
            Console.WriteLine(String.Format("Row{0}: ", i));
            Console.WriteLine("  Field1: {0}", dict["Field1"]);
            Console.WriteLine("  Field2: {0}", dict["Field2"]);
            i++;
        }

        Console.ReadLine();
    }
}

Would it be possible to define a string array or some other data structure that I could use to declare these dictionary objects? Here is some silly pseudo code help show my idea:

EDIT The variable fieldNames in the pseudo code below would be an array of names I expect, not based on the xml source field names. I will be ignoring any field names within the xml source that are not explicitly set in the fieldNames array.

var report1 = from report in doc.Root.Elements("Report1").Elements("Row")
              select new Dictionary<string, string>()
           {
              foreach (var fieldName in fieldNames)
              {
                  {fieldName, report.Elements(fieldName).First().Value}
              }
           };

Upvotes: 1

Views: 630

Answers (4)

Servy
Servy

Reputation: 203824

Don't try to do everything in a single collection initializer.

For something like this I'd create a separate method:

public static Dictionary<string, string> MapReport(XElement report)
{
    var output = new Dictionary<string, string>();
    foreach(var field in report.Elements())
    {
        output.Add(field.Name, ...);
    }
}

Then the query would be something much simpler:

var report1 = from report in doc.Root.Elements("Report1").Elements("Row")
              select MapReport(report)

Upvotes: 1

L.B
L.B

Reputation: 116138

This will give you a list of type List<Dictionary<string,string>>

var rows = doc.Descendants("Row")
           .Select(r => r.Elements()
                         .ToDictionary(x => x.Name.LocalName, x => x.Value))
           .ToList();

..

var data = rows[i]["Field1"];

Upvotes: 1

Tar
Tar

Reputation: 426

The pseudocode is actually pretty close to what you really can do. I assume there's a separate fieldNames collection that you have ready there.

IEnumerable<string> fieldNames = ...;
XDocument doc = ...;
var report1 = doc.Root.Elements("Report1").Elements("Row")
    .Select(report =>
    {
        var d = new Dictionary<string, string>();
        foreach (var fieldName in fieldNames)
        {
            d.Add(fieldName, report.Elements(fieldName).First().Value);
        }
        return d;
    });

Upvotes: 2

Thom Smith
Thom Smith

Reputation: 14086

Use Enumerable.ToDictionary:

var report1 = 
    from report in doc.Root.Elements("Report1").Elements("Row")
    select new[] {"Field1", "Field2", "Field3"}
        .ToDictionary(x => x, x => report.Elements(x).First().Value)

Upvotes: 5

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