I want to know if it is possible to read from a text file
in a faster and smarter way.
This is a typical format of my data in a text file
:
Call this "part":
ID:1;
FIELD1 :someText;
FIELD2 :someText;
FIELD3 :someText;
FIELD4 :someText;
FIELD5 :someText;
FIELD6 :someText;
FIELD7 :someText;
FIELD8 :someText;
END_ID :
01: someData;
02: someData;
...
...
48: someData;
ENDCARD:
I have thousands of them in a text file.
Is it possible to use LINQ
to read it "part" by "part"? I don't want to loop through every single line.
Will it be possible for LINQ
to start at ID:1;
and end at ENDCARD:
?
The reason for this is that i want to create a object
for every "part"...
I had something like this in mind:
string[] lines = System.IO.File.ReadAllLines(SomeFilePath);
//Cleaning up the text file of unwanted text
var cleanedUpLines = from line in lines
where !line.StartsWith("FIELD1")
&& !line.StartsWith("FIELD5")
&& !line.StartsWith("FIELD8")
select line.Split(':');
//Here i want to LINQtoText "part" by "part"
//This i do not want to do!!!
foreach (string[] line in cleanedUpLines)
{
}
Here you go:
static void Main()
{
foreach(var part in ReadParts("Raw.txt"))
{ // all the fields for the part are available; I'm just showing
// one of them for illustration
Console.WriteLine(part["ID"]);
}
}
static IEnumerable<IDictionary<string,string>> ReadParts(string path)
{
using(var reader = File.OpenText(path))
{
var current = new Dictionary<string, string>();
string line;
while((line = reader.ReadLine()) != null)
{
if(string.IsNullOrWhiteSpace(line)) continue;
if(line.StartsWith("ENDCARD:"))
{
yield return current;
current = new Dictionary<string, string>();
} else
{
var parts = line.Split(':');
current[parts[0].Trim()] = parts[1].Trim().TrimEnd(';');
}
}
if (current.Count > 0) yield return current;
}
}
What this does is: create an iterator block (a state machine that reads and "yields" data as it is iterated; it does not read the entire file in one go) that scans the lines; if it is the end of a card, the card is "yielded"; otherwise it adds the data into a dictionary for storage.
Note: if you have your own class
that represents the data, then you could use something like reflection or FastMember to set the values by name.
This does not use LINQ directly; however, it is implemented as an enumerable sequence, which is the building block of LINQ-to-Objects, so you could consume this with LINQ, i.e.
var data = ReadParts("some.file").Skip(2).First(x => x["ID"] == "123");
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