如何使用Roslyn在对象初始化器中添加换行？

要让Roslyn把对象初始化器从单行格式拆成多行，只需在你的格式化选项中添加针对对象初始化器的配置即可。

先看你当前的格式化方法：

public SyntaxNode GetFormatedNode(SyntaxNode node)
{
    var workspace = new AdhocWorkspace();
    OptionSet options = workspace.Options;
    options = options
        .WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInMethods, true)
        .WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInProperties, true)
        .WithChangedOption(new OptionKey(FormattingOptions.UseTabs, LanguageNames.CSharp), true)
        .WithChangedOption(new OptionKey(FormattingOptions.IndentationSize, LanguageNames.CSharp), 4);

    return Formatter.Format(node, workspace, options);
}

修改后的代码添加了两个关键选项：

public SyntaxNode GetFormatedNode(SyntaxNode node)
{
    var workspace = new AdhocWorkspace();
    OptionSet options = workspace.Options;
    options = options
        .WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInMethods, true)
        .WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInProperties, true)
        .WithChangedOption(new OptionKey(FormattingOptions.UseTabs, LanguageNames.CSharp), true)
        .WithChangedOption(new OptionKey(FormattingOptions.IndentationSize, LanguageNames.CSharp), 4)
        // 开启对象初始化器大括号换行
        .WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInObjectInitializers, true)
        // 可选：给对象初始化器的冒号后加空格，优化可读性
        .WithChangedOption(CSharpFormattingOptions.SpaceAfterColonInObjectInitializer, true);

    return Formatter.Format(node, workspace, options);
}

选项说明： #

• NewLinesForBracesInObjectInitializers：设置为true后，new Column { ... }会拆成两行，大括号单独起一行，内部成员自动缩进。
• SpaceAfterColonInObjectInitializer：让ID="xxx"变成ID = "xxx"，属于可选配置，可按个人代码风格调整。

修改后，你提供的示例代码：

class Example
{
    void Method()
    {
        Column col = new Column { ID = "mySuperColumnID", Code = "mySuperColumnCode" };
    }
}

会被格式化为你期望的样子：

class Example
{
    void Method()
    {
        Column col = new Column
        {
            ID = "mySuperColumnID",
            Code = "mySuperColumnCode"
        };
    }
}

内容的提问来源于stack exchange，提问作者Shems Asfouri