How to keep template whitespace (tabs) formatting using Apache Velocity 1.7?

Question

I am using Velocity to generate different artifacts in my project, including Java Hibernate Entities.

Here is an example of my template:

#foreach( $column in $columns )
    #if ($column.columnID != "id")
        #if ($column.isColumnAnIdentifier)
@Id
        #end
        #if ($column.isColumnValueGenerated)
@GeneratedValue
        #end
        #if ($column.isColumnValueNotNull)
@NotNull
        #end
        #if ($column.columnAllowedValues)
@Enumerated(EnumType.STRING)        
        #end
        #if ($column.isColumnValueUnique)
@Column(unique=true)
        #elseif ($column.isColumnJoinedManyToOne)
@ManyToOne
@JoinColumn(name = "$column.columnJoinByID")
        #else
@Column
        #end
private #if ($column.columnAllowedValues) $column.columnID.toUpperCase() #else $column.columnType #end $column.columnID;
    #end
#end

The problem is that the generated code looks like this:

@Column
            private  String  vendor;

                                                        @NotNull
                                    @Column(unique=true)
            private  String  name;


@Column
            private  Integer  min_quantity;


@Column
            private  String  description;


@Column
            private  Boolean  active;

I tried the suggested solution with adding ## after each line, it does not help. Is there a way to force Velocity to keep whitespace as defined in the template?

    VelocityEngine velocityEngine = new VelocityEngine();
    velocityEngine.setProperty(RESOURCE_LOADER_PROPERTY, RESOURCE_LOADER_VALUE);
    velocityEngine.setProperty(CLASSPATH_RESOURCE_LOADER_PROPERTY, ClasspathResourceLoader.class.getName());
    velocityEngine.init();
    Template velocityTemplate = velocityEngine.getTemplate(TEMPLATE_RESOURCES_ROOT_FOLDER + "/" + templateFileName);;
    StringWriter writer = new StringWriter();
    velocityTemplate.merge(velocityContext, writer);
    writeToFile(writer, destinationFilePath);

score 3 · Accepted Answer · answered Apr 09 '17 at 22:32

The ## at the end of lines is not enough, you also need to remove the Velocity indentation.

An alternative, to keep the indentation, is to indent with Velocity comments:

#foreach( $column in $columns )##
#**##if ($column.columnID != "id")##
#*    *##if ($column.isColumnAnIdentifier)##
@Id
#*    *##end
#*    *##if ($column.isColumnValueGenerated)##
...

but I concede it is rather ugly.

The upcoming Velocity 2.0 release adds a space gobbling option, active by default, with does exactly what you want. The latest release candidate is available here.

score 0 · Answer 2 · answered Apr 26 '18 at 09:35

I store my files without any indentation, adding it when I edit and removing it afterwards. You'll need to run this on Linux or Cygwin:

Safely ident leading Velocity instructions:

gawk '
function ltrim(s) { sub(/^[ \t\r\n]+/, "", s); return s }
BEGIN {p=""}
/^ *#(end|else)\>/ {p = substr(p,5)}
/^ *#(if|end|set|foreach|else|#)\>/ {
    printf "%s%s\n", p, ltrim($0);
    if($0 ~ /^ *#(if|foreach|else)\>/) p = p "    "; next;}
1'

Remove indentations:

sed 's/^  #/#/'

If you story these as scripts (and use vi/vim) you can then use:

:%!VelocityIndent

...otherwise just pipe the file through the script.

How to keep template whitespace (tabs) formatting using Apache Velocity 1.7?

2 Answers2