docs/user-manual/modules/ROOT/pages/file-language.adoc

[[file-language]]
= File Language
:page-source: core/camel-base/src/main/docs/file-language.adoc

*Since Camel 1.1*

The file language is merged with
xref:simple-language.adoc[Simple] language which means you can use all the file
syntax directly within the simple language.

The File Expression Language is an extension to the
xref:simple-language.adoc[Simple] language, adding file related capabilities.
These capabilities are related to common use cases working with file
path and names. The goal is to allow expressions to be used with the
File and FTP components for setting
dynamic file patterns for both consumer and producer.

== File Language options

// language options: START
The File language supports 2 options, which are listed below.



[width="100%",cols="2,1m,1m,6",options="header"]
|===
| Name | Default | Java Type | Description
| resultType |  | String | Sets the class name of the result type (type from output)
| trim | true | Boolean | Whether to trim the value to remove leading and trailing whitespaces and line breaks
|===
// language options: END

== Syntax

This language is an *extension* to the xref:simple-language.adoc[Simple] language
so the xref:simple-language.adoc[Simple] syntax applies also. So the table below
only lists the additional.  +
 As opposed to xref:simple-language.adoc[Simple] language
xref:file-language.adoc[File Language] also supports
xref:constant-language.adoc[Constant] expressions so you can enter a fixed
filename.

All the file tokens use the same expression name as the method on the
`java.io.File` object, for instance `file:absolute` refers to the
`java.io.File.getAbsolute()` method. Notice that not all expressions are
supported by the current Exchange. For instance the xref:components::ftp-component.adoc[FTP]
component supports some of the options, where as the
File component supports all of them.


[width="100%",cols="10%,10%,10%,10%,10%,25%,25%",options="header",]
|===
|Expression |Type |File Consumer |File Producer |FTP Consumer |FTP Producer |Description

|file:name |String |yes |no |yes |no |refers to the file name (is relative to the starting directory, see note
below)

|file:name.ext |String |yes |no |yes |no |refers to the file extension only

|file:name.ext.single |String |yes |no |yes |no |refers to the file extension. If the file
extension has mutiple dots, then this expression strips and only returns
the last part.

|file:name.noext |String |yes |no |yes |no |refers to the file name with no extension (is relative to the starting
directory, see note below)

|file:name.noext.single |String |yes |no |yes |no |refers to the file name with no extension (is
relative to the starting directory, see note below). If the file
extension has multiple dots, then this expression strips only the last
part, and keep the others.

|file:onlyname |String |yes |no |yes |no |refers to the file name only with no leading paths.

|file:onlyname.noext |String |yes |no |yes |no |refers to the file name only with no extension and with no leading
paths.

|file:onlyname.noext.single |String |yes |no |yes |no |refers to the file name only with no extension and
with no leading paths. If the file extension has multiple dots, then
this expression strips only the last part, and keep the others.

|file:ext |String |yes |no |yes |no |refers to the file extension only

|file:parent |String |yes |no |yes |no |refers to the file parent

|file:path |String |yes |no |yes |no |refers to the file path

|file:absolute |Boolean |yes |no |no |no |refers to whether the file is regarded as absolute or relative

|file:absolute.path |String |yes |no |no |no |refers to the absolute file path

|file:length |Long |yes |no |yes |no |refers to the file length returned as a Long type

|file:size |Long |yes |no |yes |no |refers to the file length returned as a Long type

|file:modified |Date |yes |no |yes |no |Refers to the file last modified returned as a Date type

|date:_command:pattern_ |String |yes |yes |yes |yes |for date formatting using the `java.text.SimpleDateFormat` patterns. Is
an *extension* to the xref:simple-language.adoc[Simple] language. Additional
command is: *file* (consumers only) for the last modified timestamp of
the file. Notice: all the commands from the xref:simple-language.adoc[Simple]
language can also be used.
|===

== File token example

=== Relative paths

We have a `java.io.File` handle for the file `hello.txt` in the
following *relative* directory: `.\filelanguage\test`. And we configure
our endpoint to use this starting directory `.\filelanguage`. The file
tokens will return as:

[width="100%",cols="50%,50%",options="header",]
|===
|Expression |Returns

|file:name |test\hello.txt

|file:name.ext |txt

|file:name.noext |test\hello

|file:onlyname |hello.txt

|file:onlyname.noext |hello

|file:ext |txt

|file:parent |filelanguage\test

|file:path |filelanguage\test\hello.txt

|file:absolute |false

|file:absolute.path |\workspace\camel\camel-core\target\filelanguage\test\hello.txt
|===

=== Absolute paths

We have a `java.io.File` handle for the file `hello.txt` in the
following *absolute* directory:
`\workspace\camel\camel-core\target\filelanguage\test`. And we configure
out endpoint to use the absolute starting directory
`\workspace\camel\camel-core\target\filelanguage`. The file tokens will
return as:

[width="100%",cols="50%,50%",options="header",]
|===
|Expression |Returns

|file:name |test\hello.txt 

|file:name.ext |txt

|file:name.noext |test\hello

|file:onlyname |hello.txt

|file:onlyname.noext |hello

|file:ext |txt

|file:parent |\workspace\camel\camel-core\target\filelanguage\test

|file:path |\workspace\camel\camel-core\target\filelanguage\test\hello.txt

|file:absolute |true

|file:absolute.path |\workspace\camel\camel-core\target\filelanguage\test\hello.txt
|===

== Samples

You can enter a fixed xref:constant-language.adoc[Constant] expression such as
`myfile.txt`:

[source]
----
fileName="myfile.txt"
----

Lets assume we use the file consumer to read files and want to move the
read files to backup folder with the current date as a sub folder. This
can be archieved using an expression like:

[source]
----
fileName="backup/${date:now:yyyyMMdd}/${file:name.noext}.bak"
----

relative folder names are also supported so suppose the backup folder
should be a sibling folder then you can append .. as:

[source]
----
fileName="../backup/${date:now:yyyyMMdd}/${file:name.noext}.bak"
----

As this is an extension to the xref:simple-language.adoc[Simple] language we have
access to all the goodies from this language also, so in this use case
we want to use the in.header.type as a parameter in the dynamic
expression:

[source]
----
fileName="../backup/${date:now:yyyyMMdd}/type-${in.header.type}/backup-of-${file:name.noext}.bak"
----

If you have a custom Date you want to use in the expression then Camel
supports retrieving dates from the message header.

[source]
----
fileName="orders/order-${in.header.customerId}-${date:in.header.orderDate:yyyyMMdd}.xml"
----

And finally we can also use a bean expression to invoke a POJO class
that generates some String output (or convertible to String) to be used:

[source]
----
fileName="uniquefile-${bean:myguidgenerator.generateid}.txt"
----

And of course all this can be combined in one expression where you can
use the xref:file-language.adoc[File Language], xref:file-language.adoc[Simple]
and the xref:components::bean-component.adoc[Bean] language in one combined expression. This
is pretty powerful for those common file path patterns.

== Using Spring PropertyPlaceholderConfigurer together with the File component

In Camel you can use the xref:file-language.adoc[File Language] directly
from the xref:simple-language.adoc[Simple] language which makes a
Content Based Router easier to do in
Spring XML, where we can route based on file extensions as shown below:

[source,xml]
----
<from uri="file://input/orders"/>
   <choice>
     <when>
         <simple>${file:ext} == 'txt'</simple>
         <to uri="bean:orderService?method=handleTextFiles"/>
     </when>
     <when>
         <simple>${file:ext} == 'xml'</simple>
         <to uri="bean:orderService?method=handleXmlFiles"/>
     </when>
     <otherwise>
         <to uri="bean:orderService?method=handleOtherFiles"/>
     </otherwise>
  </choice>
----

If you use the `fileName` option on the File endpoint
to set a dynamic filename using the xref:file-language.adoc[File Language] then make sure you  +
 use the alternative syntax to avoid
clashing with Springs `PropertyPlaceholderConfigurer`.

*bundle-context.xml*

[source,xml]
----
<bean id="propertyPlaceholder" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location" value="classpath:bundle-context.cfg" />
</bean>

<bean id="sampleRoute" class="SampleRoute">
    <property name="fromEndpoint" value="${fromEndpoint}" />
    <property name="toEndpoint" value="${toEndpoint}" />
</bean>
----

*bundle-context.cfg*

[source]
----
fromEndpoint=activemq:queue:test
toEndpoint=file://fileRoute/out?fileName=test-$simple{date:now:yyyyMMdd}.txt
----

Notice how we use the $simple\{ } syntax in the `toEndpoint` above. +
 If you don't do this, there is a clash and Spring will throw an
exception like

[source,java]
----------------------------------------------------------------------------------------------------
org.springframework.beans.factory.BeanDefinitionStoreException:
Invalid bean definition with name 'sampleRoute' defined in class path resource [bundle-context.xml]:
Could not resolve placeholder 'date:now:yyyyMMdd'
----------------------------------------------------------------------------------------------------

== Dependencies

The File language is part of *camel-core*.