CsvHelper: No members are mapped for type

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I use CsvHelper 4.0.3.

I have a nested class defined like this:

private class CsvLine {
    public string Solution;
    public string Project;
    public string DependsOnProject;
    public string Weight;
    public string DependsOnPackage;
    public string PackageVersion;
}

My .csv file, which I want to parse using CsvHelper, has these field names:

Solution,Project,DependsOnProject,Weight,DependsOnPackage,PackageVersion

Here is my code:

TextReader readFile = new StreamReader(dependenciesCsvFilePath);
var csvReader = new CsvReader(readFile);
IEnumerable<CsvLine> records = csvReader.GetRecords<CsvLine>();

According to the documentation here, the code above should work.

However, when I inspect records, I see the message No members are mapped for type 'ParentClass+CsvLine'.

I changed the accessibility of CsvLine from private to public, but that made no difference.

What did I do wrong?

EDIT: I have tried un-nesting the CsvLine class and making it public, but that did not help either.

EDIT: I made the changes as Nkosi suggested; however, now it says that records is an empty collection: "Enumeration yielded no results". There are definitely data present inside my .csv file, so the collection shouldn't be empty.

Here are some sample data:

Solution,Project,DependsOnProject,Weight,DependsOnPackage,PackageVersion
FOD.sln,ABC.DEF,IMS.ABC,1,,
FOD.sln,ABC.DEF,IMS.DEF,1,,
FOD.sln,ABC.DEF,IMS.GHI,1,,
FOD.sln,ABC.DEF,IMS.JKL,1,,

EDIT: Solved! Nkosi's and Panagiotis' answers complement each other's.

You need to use Properties instead of fields in the object model as by default, it will map the matching public members

public class CsvLine {
    public string Solution { get; set; }
    public string Project { get; set; }
    public string DependsOnProject { get; set; }
    public string Weight { get; set; }
    public string DependsOnPackage { get; set; }
    public string PackageVersion { get; set; }
}

You should also read up on mapping your classes to the csv file.

CsvHelper: Class Mapping

" No members are mapped for type", not on local Windows machine , What is the possible causes of this exception, that are possibly environment dependent? Stack Trace: at CsvHelper.Expressions. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. CsvHelper: No members are mapped for type. 0

Nkosi explained that CsvHelper maps to properties by default.

I've encountered the Enumeration yielded no results message in the debugger in the past. The message is misleading. There are records even though the debugger says there aren't. You iterate over the IEnumerable with foreach or call .ToArray() or .ToList() on it to load all records, eg:

var records = csvReader.GetRecords<CsvLine>();
foreach(var record in records)
{
     ...
}

Or

var records = csvReader.GetRecords<CsvLine>().ToArray();

You can force the debugger to show all items in an IEnumerable in the Watch, Quick Watch or Immediate window by adding the results format specifier, eg:

records,results

Be careful because this will execute the IEnumerable and return all results.

You can find this, and other tricks in 7 Hidden Gems in Visual Studio 2017

ClassMap · Issue #934 · JoshClose/CsvHelper · GitHub, Exception: CsvHelper.ReaderException: No members are mapped for type. Any pointers will be gratefully received. I will also need to write out  at CsvHelper.CsvReader.GetRecordsT+MoveNext() rh78 changed the title " No members are mapped for type", but only in Production System " No members are mapped for type", not on local Windows machine, but on CentOS machine Feb 12, 2019

Mapping Properties, This will map the properties of a class to the header names of the CSV data. The mapping needs to be registered in the configuration. This example is identical  Solution,Project,DependsOnProject,Weight,DependsOnPackage,PackageVersion. Here is my code: TextReader readFile = new StreamReader (dependenciesCsvFilePath); var csvReader = new CsvReader (readFile); IEnumerable<CsvLine> records = csvReader.GetRecords<CsvLine> (); According to the documentation here, the code above should work. However, when I inspect records, I see the message No members are mapped for type 'ParentClass+CsvLine'.

There is an easier solution to the problem, it's only one line of code. You have to tell csvhelper to look at your fields.

using (var csv = new CsvWriter(writer))
{
    csv.Configuration.MemberTypes = CsvHelper.Configuration.MemberTypes.Fields;
.....
}

Configuration Class, When using a class map, no members are mapped by default. Only member specified in the mapping are used. RegisterClassMap(Type), Use a CsvHelper. Mapping properties that have duplicate header names. Mapping by Index: Mapping properties by header index position. Auto Mapping: Automatic mapping. Ignoring Properties: Ignoring mapped properites. Constant Value: Setting a constant value for a property. Type Conversion: Using a specific type converter. Inline Type Conversion: Convert a field to a type inline.

As of CsvHelper 12.2.2, this is what I've had to do to get it to work

csv.Read() 
csv.ReadHeader()
csv.GetRecords<T>().ToList();

For some reason despite CsvReader's documentation, adding the Read() and ReadHeader() methods will get it to actually pull in the data from the csv file.

CsvHelper Getting Started, The culture is used to determine the default delimiter, default line ending, and formatting when type converting. You can You can't rely on the ordering of class members in .NET. We can solve this by mapping the property to a position in the CSV file. One way to We can write the records to a file without any configuration. I half suspect that I'm doing something wrong here, but I feel like I followed the examples in the documentation and can't find where I screwed up, so I'm submitting just in case there is a bug somewhere.

getting no properties are mapped for type using csvHelper, csvhelper no members are mapped for type csvhelper classmap write example csvhelper map method csvhelper classmap not working csvhelper member is not​  Gets the field converted to System.Type T at position (column) name using the specified CsvHelper.TypeConversion.ITypeConverter. ValidateHeader<T>() Validates the header. A header is bad if all the mapped members don't match. If the header is not valid, a CsvHelper.ValidationException will be thrown. ValidateHeader(Type) Validates the header.

CsvHelper.xml 1.0.6727.21992, CsvHelper: No members are mapped for type. I use CsvHelper 4.0.3. I have a nested class defined like this: private class CsvLine { public string Solution; public  I'm using Automapper to do some mapping from XSD-generated serialization object to more sane POCO's. I'm having an issue with a particular type of mapping. public class SourceOuterObject { pub

CsvHelper.dll, <member name="M:CsvHelper. The string format to be used when type converting. When using a class map, no members are mapped by default. 8 CsvHelper: No members are mapped for type; 8 How to use a linear activation function in TensorFlow? View more network posts → Top tags (7) unity. Score 0

Comments
  • Same error when un-nested?
  • Fields verses properties.
  • Where Are the headers in the file? If no headers then you will have to create a class mapping to map by index
  • Use .GetRecords<CsvLine>().ToArray() to load the data first, then check them. I've seen the debugger complain about an empty enumeration even though there were records. BTW which version of CsvHelper are you using? It changes versions almost every week
  • @PanagiotisKanavos Calling ToArray() did the trick. Thank you!
  • Thank you for your reply! I made the changes as you suggested; however, now it says that records is an empty collection: "Enumeration yielded no results". There are definitely data present inside my .csv file, so the collection shouldn't be empty.
  • I had same symptom as @my_g and resolved it by changing private setters to public setters on all properties.
  • The class mapping link was 404 not found as of Jan 2020. Please go here instead: joshclose.github.io/CsvHelper/…
  • @LeonardAB I fixed the link. Thank you for the heads up.