Velocity Variable Replacement

Mirth® Connect by NextGen Healthcare User Guide

The Variable Map Lookup Sequence

In many cases when referencing map variables in Mirth® Connect, you do not call out to a specific map, but instead use the generic lookup function: var value = $('variableName'); Or, you might reference a variable using Velocity Variable Replacement: ${variableName} When you do this, Mirth® Connect will automatically look that key up in all available maps. That may only be the configuration/global map (in the case of the global scripts) , or it may be all maps (in the case of a filter / transformer script) . This sequence is followed: Response Map Connector Map Channel Map Source Map Global Channel Map Global Map Configuration Map For example, if you have stored a variable called "dataSource" in both the Connector Map and the Global Channel Map, the one from the Connector Map will be used. If you want the value specifically from the Global Channel Map instead, you can use the map-specific get function shown in the Variable Maps section: var dataSource = globalChannelMap.get('dataSource

Mirth® Connect by NextGen Healthcare User Guide

Channel Writer

The Channel Writer is a connector that simply dispatches messages to other internal channels. This can be useful if you split your message workflow into multiple channels, where one sends to another. If no target channel is specified, the connector acts as a "sink" where no message dispatching is done. Note that a channel does not need to use a Channel Reader source for a Channel Writer to be able to send messages to it. The connector also has options to inject source map variables into the downstream message of the target channel. Supported property groups: Destination Settings Item Name Default Value Description A Channel Id <None> The unique ID of the target channel to send messages to. This may be a hard-coded ID, or may be a Velocity Variable Replacement. Use the drop-down menu to the right to quickly select a particular channel. If <None> is selected, the destination will act as a "sink" where messages are not dispatched anywhere. B Message Metadata The map variables entered here

Mirth® Connect by NextGen Healthcare User Guide

Destination Connector Properties

This section refers to the actual connector-specific settings. The section is labeled according to the connector type, e.g. "HTTP Sender Settings", "JavaScript Writer Settings". Here is a list of destination connectors supported by Mirth® Connect: Destination Connectors Channel Writer DICOM Sender Database Writer Document Writer File Writer HTTP Sender JMS Sender JavaScript Writer SMTP Sender TCP Sender Web Service Sender Additional destination connectors are made available as extensions: Serial Connector NextGen Results CDR Connector FHIR Connector Interoperability Connector Suite Parent topic: Destinations Tab

Mirth® Connect by NextGen Healthcare User Guide

Conditional Statements

Velocity supports if..else statements, with the #if / #elseif / #else directives: There #if($list.size()==1)is#{else}are#end ${list.size()} total value#if($list.size()!=1)s#end The curly brackets ("{}") are only needed if the if/else/end might be confused with template data immediately before or after. Parent topic: Velocity Variable Replacement

Mirth® Connect by NextGen Healthcare User Guide

Batch Processing

Batch Processing allows a channel to receive a single message, but split it into multiple messages that each get processed through the channel. When using this along with a source connector that supports streaming (File Reader, TCP Listener in MLLP mode), batch processing has the added benefit of not having to read the entire file into memory all at once, but instead only one message at a time. For example with the File Reader and batch processing you can read in files that are gigabytes in size, without causing any memory issues for your Mirth Connect server. Data types that support batch processing will have a Batch Properties section in the source inbound data type properties. To enable batch processing, set Process Batch to Yes in the Source Settings. To change how an incoming message is split into multiple messages, look at the Batch Properties section of the source inbound data type you are using. For example, the Delimited Text Data Type has options to split by record delimiter,

Mirth® Connect by NextGen Healthcare User Guide

Basic Syntax

Basic syntax for a Velocity reference is as follows: ${variableName} The brackets may be omitted if the identifier starts with a letter and contains only letters, numbers, hyphens, or underscores: $variableName The variable will be looked up in all available maps, according to The Variable Map Lookup Sequence. The string representation of the value will then replace the Velocity reference. You can also access properties and methods from context variables: ${myArray.length}${myList.size()}${myObject.customMethod('param')} If a property has a corresponding getter method (like getValue()), the engine will automatically find that method when you attempt to access the property. Therefore these may be equivalent: ${myObject.value}${myObject.getValue()} If the context variable doesn't exist, or if the value returned by the reference evaluation is null, no replacement will be done, so the final template will still have your "${varName}" string within. In these cases you can put an exclamation

Velocity Variable Replacement

Recommendations

The Variable Map Lookup Sequence

Channel Writer

Destination Connector Properties

Conditional Statements

Batch Processing

Basic Syntax

The Variable Map Lookup Sequence

Channel Writer

Destination Connector Properties

Conditional Statements

Batch Processing

Basic Syntax