attributeHasMetaData (metaDataKey)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

..	list-table:: 
	:widths: 20 80
	:header-rows: 0
	:class: tight-table

	*	-	Category
		-	metadata functions
	*	-	Signature
		-	attributeHasMetaData(String metadataKey) : boolean
	*	-	Description
		-	Checks if the model attribute in the context has a certain metadata key.
	*	-	Arguments
		-	metaDataKey: key of metadata to check for existence
	*	-	Returns
		-	- true if the model attribute in the context has the metadata key,
			- false if the model attribute in the context does not have the metadata key.
	*	-	Exceptions
		- .. error::
			This function raises a *No model attribute in context* exception when the context does not contain a model attribute.
	*	-	Example
		-	The following example shows a code instruction that generates a Java class for each object, 
			with a Java field that is transient for each attribute that has metadata *transient*.
			
			Given the input shown in the input section below CodeComposer will generate the field only for attribute *exampleAttribute2* as shown in the output section below.
			
			**Input**
			
			.. code-block:: xml
				:caption: src/codeinstruction/examples/example-code-instruction-simple-entity-foreach-attribute-and-attribute-has-meta-data.xml
				:name: AttributeHasMetaData_CodeInstruction
				:linenos:
				:emphasize-lines: 12, 13
				
				<?xml version="1.0" encoding="UTF-8"?>
				<java_package xmlns="https://metafactory.io/xsd/v1/java-codeinstruction"
				              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
				              xsi:schemaLocation="https://metafactory.io/xsd/v1/java-codeinstruction https://metafactory.io/xsd/v1/java-codeinstruction.xsd"
				              name="${pattern.property.java.package.base}.entities.simple"
				              path="${pattern.property.java.main.directory}"
				              package="domain_model">
					<class  name="${createSimpleEntityClassName(${object.name})}"
					        foreach="object">
						<field name="${attribute.name}"
						       foreach="attribute"
						       condition="${attributeHasMetaData(transient)}"
						       transient="true"
						       access="rw"
						>
							<datatype>${attribute.type}</datatype>
						</field>
					</class>
				</java_package>
			
			.. code-block:: xml
				:caption: src/model/model.xml
				:name: AttributeHasMetaData_Model
				:linenos:
				:emphasize-lines: 7, 8, 12

				<?xml version="1.0" encoding="UTF-8"?>
				<model xmlns="https://metafactory.io/xsd/v1/model" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://metafactory.io/xsd/v1/model https://metafactory.io/xsd/v1/model.xsd">
					<package name="domain_model">
						<object name="ExampleObject1">
							<metadata></metadata>
							<attribute name="exampleAttribute1" type="String">
								<metadata>
								</metadata>
							</attribute>
							<attribute name="exampleAttribute2" type="Long">
								<metadata>
									<transient></transient>
								</metadata>
							</attribute>
						</object>
					</package>
				</model>
			
			**Output**

			.. code-block:: java
				:caption: src/main/java/io/metafactory/codecomposer_reference/entities/simple/ExampleObject1SimpleEntity.java
				:name: AttributeHasMetaData_Output1
				:linenos:
				:emphasize-lines: 6

				package io.metafactory.codecomposer_reference.entities.simple;

				public class ExampleObject1SimpleEntity
				{
					private String exampleAttribute1;
					private transient Long exampleAttribute2;
				}