Setting a number of loop iterations in a flat structure

Use a SetElementProperty to define the number of loops to read for an element and ignore other iterations.

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1. Create your structure:
   1. In the Hierarchical Mapper, right-click Structures and click New > Structure.
   2. In the wizard that opens, select Create a new structure where you manually enter elements and click Next.
   3. Select a folder and enter a name for your structure, then click Next.
   4. Select the Flat Files representation and click Next.
   5. Click Import a file as document and click Next.
   6. Browse to the relevant folder and select your flat file, then click Finish.
2. Right-click the section on the left of your workspace and click New Element to create a root element.
3. Right-click the root element and create three child elements named a, b and c.
   Your structure should look like this:

   

4. Click the a element and enter 2 in both Size Min/Max fields, then enter the same values for the c element.
5. Click the b element and enter 1 in the Occurs Min field, 100 in Occurs Max and 2 in both Size Min/Max fields.
   This indicates that the element must occur once and can occur up to 100 times, and each iteration has a size of two bytes.

   

6. Drag and drop a SetElementProperty function in the Util tab of the b element.
7. Double-click the SetElementProperty function and select Loop Count in the Property drop-down list.
8. Drag and drop a Constant function on the Value argument, then double-click the function, enter 3 in the Value field and click OK.
   This indicates that only the first three iterations of the b elements should be read.

   

   The number of loops to read is defined but an error appears because there are no instructions on how to process the rest of the file.
9. Drag and drop a SetElementProperty function in the Util tab of the c element and leave the default Byte offset property.
10. Drag and drop a Constant function on the Value argument, then double-click the function, enter 12 in the Value field and click OK.
    This expression indicates that the c element starts 12 bytes after the first byte in the document, which means that the two loop iterations ignored in the b elements are discarded and not read as part of the c element.

Results

Your structure is configured. If you want to check that the properties are correct, you can create a map with this structure as both input and output.

When using the Test Run feature, you should get the following result:

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If needed, you can change the Loop Count property in the map, without impacting the structure or any other map which uses it.