Loops

Usually in a task relating to a database or list you want to do the same thing to one of a set of records, e.g. display each record retrieved by a search or each term in a section of the inverted file.

For the tasks mfnrange, search and keyrange this is done using a loop – the loop starts again for each record until the last record in the set has been processed.\ The loop is specified with the tags <loop> and </loop>.\ For the task update, the tags <update> and </update> are used.

You can use a loop in the hello.xis script to display the message several times (specified by the parameter to). This does not need a task specifying as it is not operating on a database. The loop part is indented in this example to emphasize where the loop starts and ends.

<IsisScript name=Hello>
    <display><pft>’Content-type: text/html’##</pft></display>
    <do>
        <parm name = to>10</parm>
        <loop>
            <display>Hello world!<br></display>
        </loop>
    </do>
</IsisScript>

A simple script to display the MFN and title of the first ten records in the CDS database could be written like this.

<IsisScript name=ShowTen>
    <display><pft>’Content-type: text/html’##</pft></display>
    <do task = mfnrange>
        <parm name=db>cds</parm>
        <parm name=from>1</parm>
        <parm name=to>10</parm>
        <loop>
            <display><pft>mfn,' – ',v24,'<br>'</pft></display>
        </loop>
    </do>
</IsisScript>