# Fixed Length Serializer

*Fixed Length Serializer* is useful when source data is stored in multiple fields and is to be converted to text format (store entire data in a single field). This is helpful is scenarios where you have to:

* Store large datasets, so you compress the information in a single field
* Transport volumes of data over a network

In this document, we will learn how to use *Fixed Length Serializer* in Astera.

### Sample Use-Case

In this case, we are using an [*Excel Workbook Source*](/dataflows/sources/excel-workbook-source.md).

![](/files/ARqwfRrpVTsigtOqB0u0)

The source file contains customers’ *ContactDetails*.

To preview this data, right-click on the source object’s header, and select *Preview Output* from the context menu.

![](/files/QPNcUTrIBxPmWIFGSi2T)

A *Data Preview* window will open, displaying the source data.

![](/files/VO57Gj1I0ibaBCUtTfcw)

Now, we want to convert the information contained in multiple fields into a single field in text format.

To perform this task, we will use the *Fixed Length Serializer* object in Astera.

#### Using Fixed Length Serializer

1. To get the *Fixed Length Serializer* object, go to *Toolbox > Text Processors > Fixed Length Serializer*, and drag-and-drop the object onto the designer.

![](/files/5v0Idr1nKRYu8ff4djln)

You can see that the dragged-object contains a *Text* field and an *Input* sub-node which is currently empty.

2. Auto-map source fields by dragging-and-dropping top node of the source object, *ContactDetails*, onto the *Input* node of the transformation object – *Fixed Length Serializer*.

![](/files/PdxwoNr2Xmq2bWBySHNP)

3. Right-click on the object’s header and select *Properties*.

![](/files/nt7MTrZ7nKcvwDkQccBG)

A configuration window will open, as shown below.

![](/files/zVRS0koGMiMhETj2Ucmz)

4. Check the options according to the contents and format of your source file.

In this example, both options have been checked, as the first row in the source file contains header, and the data also contains multiple records.

![](/files/s7MDzQvbE7VBtkvhBXXa)

5. Specify the *Record Delimiter* of the source data. In this case, it is <*CR*><*LF*>.

You can specify any delimiter based on the format of your source file.

![](/files/P26pWtrww7YL8rhgr4LQ)

6. Under the *Builder Options*, select the relevant type from the drop-down list. For this dataset, we will use *One Record Per Input*.

![](/files/gR7F97J1ihN8hLkL49jg)

7. Click *Next*. This will open the *Destination Fields* screen, where you can see all the incoming fields from the source object.

![](/files/dZQJVqrCQZIxz4MV7CEe)

Here you can delete fields, change their *Header* or *Data Type*, modify the string’s *Start Position*, define field *Length*, and customize the fields according to your requirements.

Click *OK*.

8. Right-click on the *Fixed Length Serializer* object, and select *Preview Output*.

![](/files/kAAfaJ7KFKZrK3vli4Tt)

A *Data Preview* window will open, displaying the serialized data.

![](/files/48OmhBKRhhOWbhQXYWGl)

To store this serialized output, write it to a destination file.

9. Right-click on the *FixedLengthSerializer* node, and go to *Write to > Fixed Length File Destination*. A *Fixed Length File Destination* object is added to the dataflow designer with a *Text* field auto-mapped to it.

![](/files/cIO9WdPnkiwExVMYedQ8)

10. Configure settings for the [*Fixed Length File Destination*](/dataflows/destinations/fixed-length-file-destination.md) object.

Learn to configure settings for a *Fixed Length File Destination* from [here](/dataflows/destinations/fixed-length-file-destination.md).

11. Click on the *Start Dataflow* icon, located in the toolbar at the top, to create the destination file.

![](/files/e598QS2xtuShBCJaLXfI)

A *Fixed Length File Destination* file will successfully be created. You can find its link in the *Job progress* window.


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