<MvDO>

<MvDO> works in two somewhat different ways, depending on whether NAME and VALUE are present. If they are specified, the function is the only code in the external file that gets executed. ALL other Miva Script and HTML code is ignored. This allows you to create librarys of functions stored in external compiled files.

If NAME and VALUE are omitted, everything in the external file is executed, however any script contained within MvFUNCTION blocks are ignored. Starting at the beginning of the file, the results of all <MvASSIGN> tags are available to the calling program. All system and global variables, and all open databases, are available to the code in the external file. For example a file could contain initialization script, setting global variables and opening databases.

Attributes

• FILE: Required. This is the path and name of the compiled file. If it is a relative path is is relative to the current file.
• NAME: Optional. If NAME and VALUE are omitted. The file filename is processed as if it were included in the current file. Any output from the external file is merged into the current file. If Included, it is the name assigned to the variable which will contain the results. Normally a literal, this can also contain an expression that results in a variable name. 
• VALUE: The expression that calls the external function. The syntax for the external function is the same as for any other Miva Script function.

Note: If the required attribute FILE is missing, a value (error message) for the variable mvdo_error is set, and the script continues processing.

Examples

Including external files:

<MvDO> tags can be nested in the sense that the file filename specified by the <MvDO> can itself contain an <MvDO>. The filename path specified by the "nested" <MvDO> is relative to the location of the file containing that <MvDO> (unless it starts with a forward slash, it which case it is relative to the Miva Script document root directory).

Note: There is a limit on the number of nested MvDO calls at run-time. This limit is fixed at 23 for Miva Merchant Mia; the default limit for Miva Merchant Empresa is 23 by default, but this can be changed by the server administrator via the maxfunctiondepth setting in the global configuration file.

Miva does not interpret server-side includes (SSI). <MvDO> can simulate the effect of an SSI of the type used to include another document in the current document. For example:

<!--#include file="/external.html"-->

This can be replaced by:
<MvDO FILE="/external.html">

Calling external functions:

Libraries of common functions can be compiled to separate files and called by your programs.

In this example a file named myemail.mvc contains a function called SendEmail() used to send an email message. The file could contain many other user functions for validating email address or receiving email.

<MvDO FILE="myemail.mvc" NAME="g.ok" VALUE="{ SendEmail( to, from, cc, subject, headers, message) }">

An alternate syntax exists for calling external function without using <MvDO> where the file name can be specified using square brackets (e.g. [ 'filenam.mvc' ].function_name() )

In this example three variations on this method are shown.

<MvASSIGN NAME="g.result" 
          VALUE="{ [ g.module_email ].SendEmail( to, from, cc, subject, headers, message) }">

<MvEVAL VALUE="{ [ g.module_email ].SendEmail( to, from, cc, subject, headers, message) }">

<MvIF EXPR="{ NOT [ g.module_email ].SendEmail( to, from, cc, subject, headers, message) }">
    Your email COULD NOT be sent.
<MvELSE>
    Your message was sent.
</MvIF>