删除YAML文件中键值对之前的破折号

Question

It is known that the dash ( - ) in a YAML file before the key value pair is necessary to show that it is separate block(it is what I think). Figure 1 shows the YAML I'm generating using YamlBeans jar.

field1:
-  childfield1:
      datafield1:
         param1:
            childparam: paramvalue
         param2:
            childparam2: paramvalue
         param3:
            childparam3: paramvalue
      datafield2: value2

For my codebase can't be changed, I have to somehow create the YAMLs as shown in Figure 2 (a tab is appended in each line in yaml file) or remove the dash is removed. You can clearly observe that there are only two thin vertical lines in Figure 1 but three thin vertical lines in Figure 2 which shows the alignment of the blocks.

What I want to achieve is to remove that dash from the first block (at the child field) from the file. Using a YAML file reader and writer always introduces the dash.

Answer 1

Glancing quick at (but admittedly not being familiar with) YamlBeans, it doesn't look like it's easy to subclass the behavior of the Emitter. One option though is to generate a temporary form in memory, then manipulate the results when writing out to a file. For example

    // let YamlWriter write its contents to an in-memory buffer
    StringWriter temp = new StringWriter();
    YamlWriter yamlOut = new YamlWriter(temp);
    yamlOut.write(someObject);

    // then dump the in-memory buffer out to a file, manipulating lines that
    // start with a dash
    PrintWriter out = new PrintWriter(new FileWriter(new File("someoutput.dat")));
    LineNumberReader in = new LineNumberReader(new StringReader(temp.toString()));
    String line;
    while ((line = in.readLine()) != null) {
        if (line.startsWith("-")) {
            line = line.substring(1);
        }
        out.println(line);
    }

my specifics may be off, but hopefully the approach of doing simple manipulations of a temporary copy is clear enough.

If I were personally doing this, I'd probably write a custom subclass of java.io.Writer and do the manipulation on the fly (but i haven't gone through YamlWriter/Emitter in enough detail to provide an example on how to do that)