FixedWidthParserWriter

Library (C# .NET) for Parsing(Reading) & Writing fixed-width/flat data files (.txt, others).
Uses FastMember instead of slower Reflection.
It is targeting NetStandard 2.0 so it can be used on project targeting NetCore(2.0+) or NetFramework(4.6.1+).
Config base on POCO class/object model with Attributes.

There are 2 main types of usage that are explained in the following segments:
1. LineFields
2. FileFields and
3. CustomFileFields (additional third type or 2.b)
All are simple to use and easily configured with Attributes.

Logo: <img src="logo.png" height=30>

Installation

Available on latest version.
Package manager console command for installation: Install-Package FixedWidthParserWriter

Support

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Want to Contact for Development & Consulting: www.codis.tech (Quality Assurance)

Contributing

Please read CONTRIBUTING for details on code of conduct, and the process for submitting pull requests.
When opening issues do write detailed explanation of the problem or feature with reproducible example.

*Also take a look into others packages:
Open source (MIT or cFOSS) authored .Net libraries (@Infopedia.io personal blog post) | № | .Net library | Description | | - | ------------------------ | -------------------------------------------------------- | | 1 | EFCore.BulkExtensions | EF Core Bulk CRUD Ops (Flagship Lib) | | 2 | EFCore.UtilExtensions | EF Core Custom Annotations and AuditInfo | | 3 | EFCore.FluentApiToAnnotation | Converting FluentApi configuration to Annotations | | 4 | FixedWidthParserWriter | Reading & Writing fixed-width/flat data files | | 5 | CsCodeGenerator | C# code generation based on Classes and elements | | 6 | CsCodeExample | Examples of C# code in form of a simple tutorial |

CONFIG

FixedWidthConfig options (provides configuration for the Provider): defaultValue

int StructureTypeId : 0	............................... // for multiple Attributes structure
Dictionary<string, FixedWidthAttribute> DynamicSettings	// Attributes defined at runtime
bool LogAndSkipErrors: false .......................... // when True parsing exception skipped
List<string> ErrorsLog : new List<string>() ........... // output field, logs ErrorMessages
List<string> WarningsLog : new List<string>() ......... // output field, List for Warnings

*-Special feature is 'DYNAMIC Settings' with which Attributes values can be defined at runtime, for all usage types.
Data is forwarded using Dict with PropertyName and new independent Attribute with parameter values:
Dictionary<string, FixedWidthAttribute> dynamicSettings.
It can be set for all needed Properties when having no Attributes, or just add/override some specific.
And if need to exclude ones that has regular Atribute then set it with Null.
Sample in test LineParserTest.

WarningsLog filled when Writing string is cut to fit into defined position.

1. Data in LineFields

First is regular flat data file;
Record per Line (Fixed-Width), for example:

No |         Description         | Qty |   Price    |   Amount   |
  1.Laptop Dell xps13                  1       821.00       821.00
  2.Monitor Asus 32''                  2       478.00       956.00

For parsing/writing we make a model which Properties have [FixedWidthLineField] Attribute:

public class InvoiceItem
{
    [FixedWidthLineField(Start = 1, Length = 3)]
    public int Number { get; set; }

    [FixedWidthLineField(Start = 4, Length = 1)]
    public string NumberedBullet { get; set; } = ".";

    [FixedWidthLineField(Start = 5, Length = 30)]
    public string Description { get; set; }

    [FixedWidthLineField(Start = 35, Length = 6)]
    public int Quantity { get; set; }

    [FixedWidthLineField(Start = 41, Length = 13)]
    public decimal Price { get; set; }

    [FixedWidthLineField(Start = 54, Length = 13)]
    public decimal Amount => Quantity * Price;
}

Then we can call it like this:

// dataLines stripped of header
public List<Invoiceitem> ParseFieldsFromLines(new List<string> dataLines)
{
    List<InvoiceItem> invoiceItems = new FixedWidthLinesProvider<InvoiceItem>().Parse(dataLines);
    return invoiceItems;
}

public List<string> WriteFieldsToLines(List<InvoiceItem> invoiceItems)
{
    List<string> dataLines = new FixedWidthLinesProvider<InvoiceItem>().Write(invoiceItems);
    return dataLines;
}

[FixedWidthLineField] has following parameters that can be configured for each Property:

Start - required for LineType so that order of lineFields does not depends on order of modelPropertis
Length - when writing if Property value longer then defined in Length it is cut from the right to fit - valueTrim;
zero 0 value means entire line and negative values means start from Right side
Format - Defaults per data type or group
Pad - Defaults per data category: { PadNumeric = ' ', PadNonNumeric = ' ' }
PadSide - Defaults per data category: { PadSideNumeric = PadSide.Left, PadSideNonNumeric = PadSide.Right }
DoTrim - Default is 'True' when text will be trimmed before casting
StructureTypeId - Default = 0, used when having multiple files with different structure or format for same data
NullPattern - Default = string.Empty, Pattern used to represent a null value

_Format* types:
-FormatNumberInteger Default = "0", *groupFormat:Int32,Int64
-FormatNumberDecimal Default = "0.00", *groupFormat:Decimal,Single,Double
("0;00" - Special custom Format that removes decimal separator: 123.45 -> 12345)</pre>
-FormatBoolean . . . . . . Default = "1; ;0" ("ValueForTrue; ValueForNull; ValueForFalse")
-FormatDateTime. . . . . .Default = "yyyyMMdd"
Custom format strings for Numeric and DateTime.

When need more then 1 file structure/format we can put multiple Attributes per Property with different StructureTypeId.
Next example shows 2 structures, second has one less Property and different PadNumeric: '0' instead of ' '(space).
To change DefaultConfig per StructureType, model should implement IFixedWidth interface with SetDefaultConfig() func.

public enum ConfigType { Alpha, Beta }

public class InvoiceItem : IFixedWidth
{
    public DefaultConfig GetDefaultConfig(int StructureTypeId)
    {
        var defaultConfig = new DefaultConfig();
        switch ((ConfigType)StructureTypeId)
        {
            case ConfigType.Alpha:
                // config remains initial default
                break;
            case ConfigType.Beta:
                defaultConfig.PadNumeric = '0';
                break;
        }
        return defaultConfig;
    }

    [FixedWidthLineField(StructureTypeId = (int)ConfigType.Alpha, Start = 1, Length = 3)]
    [FixedWidthLineField(StructureTypeId = (int)ConfigType.Beta,  Start = 1, Length = 4)]
    public int Number { get; set; }

    [FixedWidthLineField(StructureTypeId = (int)ConfigType.Alpha, Start = 4, Length = 1)]
    public string NumberedBullet { get; set; } = ".";

    [FixedWidthLineField(StructureTypeId = (int)ConfigType.Alpha, Start = 5, Length = 30)]
    [FixedWidthLineField(StructureTypeId = (int)ConfigType.Beta,  Start = 5, Length = 30)]
    public string Description { get; set; }

    //... Others Properties
}

Beta Structure:

No |         Description         | Qty |   Price    |   Amount   |
0001Laptop Dell xps13             0000010000000821.000000000821.00
0002Monitor Asus 32''             0000020000000478.000000000956.00

Calling the methods:

var linesProvider = new FixedWidthLinesProvider<InvoiceItem>();
List<InvoiceItem> itemsA = linesProvider.Parse(dataLinesA, (int)ConfigType.Alpha);
List<InvoiceItem> itemsB = linesProvider.Parse(dataLinesB, (int)ConfigType.Alpha);

PARSE method for all use cases can also optionally have third parameter List<string> errorLog which when sent as Empty list(not null) will be loaded with list of Exceptions if any were to happen during parsing and casting operations. When method is called without this param, which remains null, in that case first e

FixedWidthParserWriter

Install / Use

README