CA1303: Do not pass literals as localized parameters

Property	Value
Rule ID	CA1303
Title	Do not pass literals as localized parameters
Category	Globalization
Fix is breaking or non-breaking	Non-breaking
Enabled by default in .NET 8	No

Cause

A method passes a string literal as a parameter to a .NET constructor or method and that string should be localizable.

This warning is raised when a literal string is passed as a value to a parameter or property and one or more of the following situations is true:

• The LocalizableAttribute attribute of the parameter or property is set to true.

• The literal string is passed to the string value or string format parameter of a Console.Write or Console.WriteLine method overload.

• Rule CA1303 is configured to use the naming heuristic, and a parameter or property name contains the phrase Text, Message, or Caption.

By default, this rule analyzes the entire codebase, but this is configurable.

Rule description

String literals that are embedded in source code are difficult to localize.

How to fix violations

To fix a violation of this rule, replace the string literal with a string retrieved through an instance of the ResourceManager class.

For methods that don't require localized strings, you can eliminate unnecessary CA1303 warnings in the following ways:

• If the naming heuristic option is enabled, rename the parameter or property.
• Remove the LocalizableAttribute attribute on the parameter or property, or set it to false ([Localizable(false)]).

When to suppress warnings

It's safe to suppress a warning from this rule if either of the following statements applies:

• The code library will not be localized.
• The string is not exposed to the end user or a developer using the code library.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA1303
// The code that's violating the rule is on this line.
#pragma warning restore CA1303

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.CA1303.severity = none

For more information, see How to suppress code analysis warnings.

Configure code to analyze

Use the following options to configure which parts of your codebase to run this rule on.

• Exclude specific symbols
• Exclude specific types and their derived types
• Use naming heuristic

You can configure these options for just this rule, for all rules it applies to, or for all rules in this category (Globalization) that it applies to. For more information, see Code quality rule configuration options.

Exclude specific symbols

You can exclude specific symbols, such as types and methods, from analysis. For example, to specify that the rule should not run on any code within types named MyType, add the following key-value pair to an .editorconfig file in your project:

dotnet_code_quality.CAXXXX.excluded_symbol_names = MyType

Allowed symbol name formats in the option value (separated by |):

• Symbol name only (includes all symbols with the name, regardless of the containing type or namespace).
• Fully qualified names in the symbol's documentation ID format. Each symbol name requires a symbol-kind prefix, such as M: for methods, T: for types, and N: for namespaces.
• .ctor for constructors and .cctor for static constructors.

Examples:

Option Value	Summary
dotnet_code_quality.CAXXXX.excluded_symbol_names = MyType	Matches all symbols named MyType.
dotnet_code_quality.CAXXXX.excluded_symbol_names = MyType1|MyType2	Matches all symbols named either MyType1 or MyType2.
dotnet_code_quality.CAXXXX.excluded_symbol_names = M:NS.MyType.MyMethod(ParamType)	Matches specific method MyMethod with the specified fully qualified signature.
dotnet_code_quality.CAXXXX.excluded_symbol_names = M:NS1.MyType1.MyMethod1(ParamType)|M:NS2.MyType2.MyMethod2(ParamType)	Matches specific methods MyMethod1 and MyMethod2 with the respective fully qualified signatures.

Exclude specific types and their derived types

You can exclude specific types and their derived types from analysis. For example, to specify that the rule should not run on any methods within types named MyType and their derived types, add the following key-value pair to an .editorconfig file in your project:

dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = MyType

Allowed symbol name formats in the option value (separated by |):

• Type name only (includes all types with the name, regardless of the containing type or namespace).
• Fully qualified names in the symbol's documentation ID format, with an optional T: prefix.

Examples:

Option Value	Summary
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = MyType	Matches all types named MyType and all of their derived types.
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = MyType1|MyType2	Matches all types named either MyType1 or MyType2 and all of their derived types.
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = M:NS.MyType	Matches specific type MyType with given fully qualified name and all of its derived types.
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = M:NS1.MyType1|M:NS2.MyType2	Matches specific types MyType1 and MyType2 with the respective fully qualified names, and all of their derived types.

Use naming heuristic

You can configure whether parameters or property names containing Text, Message, or Caption will trigger this rule.

dotnet_code_quality.CA1303.use_naming_heuristic = true

Example

The following example shows a method that writes to the console when either of its two arguments are out of range. For the hour argument check, a literal string is passed to Console.WriteLine, which violates this rule. For the minute argument check, a string that's retrieved through a ResourceManager is passed to Console.WriteLine, which satisfies the rule.

<Assembly: System.Resources.NeutralResourcesLanguageAttribute("en-US")>
Namespace GlobalizationLibrary

    Public Class DoNotPassLiterals

        Dim stringManager As System.Resources.ResourceManager

        Sub New()
            stringManager = New System.Resources.ResourceManager(
                "en-US", System.Reflection.Assembly.GetExecutingAssembly())
        End Sub

        Sub TimeMethod(hour As Integer, minute As Integer)

            If (hour < 0 Or hour > 23) Then
                'CA1303 fires because a literal string
                'is passed as the 'value' parameter.
                Console.WriteLine("The valid range is 0 - 23.")
            End If

            If (minute < 0 Or minute > 59) Then
                Console.WriteLine(
                    stringManager.GetString("minuteOutOfRangeMessage",
                        System.Globalization.CultureInfo.CurrentUICulture))
            End If

        End Sub

    End Class

End Namespace

public class DoNotPassLiterals
{
    ResourceManager stringManager;
    public DoNotPassLiterals()
    {
        stringManager = new ResourceManager("en-US", Assembly.GetExecutingAssembly());
    }

    public void TimeMethod(int hour, int minute)
    {
        if (hour < 0 || hour > 23)
        {
            // CA1303 fires because a literal string
            // is passed as the 'value' parameter.
            Console.WriteLine("The valid range is 0 - 23.");
        }

        if (minute < 0 || minute > 59)
        {
            Console.WriteLine(stringManager.GetString(
            "minuteOutOfRangeMessage", CultureInfo.CurrentUICulture));
        }
    }
}

See also

• Resources in .NET apps
• Community request for change of behavior