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EMF Validation for Datatype constraints
August 26, 2014 | 2 min ReadAfter defining a model, it is a common next step to define validation rules. Often there is a requirement to have attributes with a restricted length or attributes with values in a specific range. Furthermore, it can be the case, that there are multiple attributes with the same restriction in different places of the model. To solve such a requirement EMF offers a simple solution: EDataTypes with Annotations.
This is a step-by-step guide how to define your own restricted DataType.
First, you need to define a DataType:
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Then the properties of the DataType must be set, this includes the actual Type (the Instance Type Name) and the new Name of the custom DataType:
https://eclipsesource.com<https://lh6.googleusercontent.com/wXiRcFC_9QUbhXs02SvaO_QJ2ppkOMMEy-NpcLd0J3ifVQCrLxuVqR5-x2vKnQa8bW5sbzGyd8yiU5-qHi3ECzWNw5y8Mfe2Zjs1CK-T73ElWJs8b1mSkqqyIbZbMMfRwg> does not existIn the next step, you must define the constraints with an Annotation on the DataType:
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In the properties of the Annotation, the source must be set to “https:///org/eclipse/emf/ecore/util/ExtendedMetaData”:
https://eclipsesource.com<https://lh5.googleusercontent.com/FqV06_mYhACiAGdy0LcBV9MG_vG0viTE1_4uBXuaYxk2GAdCaCNNR0AZ34Enqti8g_LBSVb5rfQ6OtLpPNOf21kWZMJjhVWLI25_2j7zyDRC2EuE4SSVtjgrGiQK3r-mRQ> does not existTo define the constraints, a Details Entry must be added to the annotation:
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The key of the Details Entry corresponds to the constraint type and the value corresponds to the constraint value:
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https://eclipsesource.com<https://lh5.googleusercontent.com/BEu5OoFMw5zOi30ztBwtZ0esgUXCgzSi_nTYLYGa5YnjVwxiAYa6RHeJf_V0trl0vJ9g1vsRAzIk9MIgDE4d2aZt-KpO5wR1MQVwnOz4jegND0xCPKjgLxde7VAj2WebQg> does not existYou can now use this definition as an attribute type of any EAttribute in the model:
https://eclipsesource.com<https://lh6.googleusercontent.com/CY6e4VaaxxfdjlcPM418suPeUXJ-xU6PPXgstRtXtQFyGCb4xsbyDJQxmQraaaCBxPBwVNyrJWnTSLF-T0bodXEHVhjUY8x1BZ3STm5SM1nfmYcQLCTlI0Le-DEAsLbS4A> does not existAn attribute with such an AttributeType will automatically provide validation results, e.g. via the Diagnostician. Therefore, frameworks like EMF Forms will automatically evaluate and display them:
https://eclipsesource.com<https://lh4.googleusercontent.com/NCAqzleMBHqNzRI00U_Lj1be5h6QKqpGpxjMGEtpeR_LA9G8ogUyrbXNqgnVKnTVQ_Cip-xVekRugC7YHRaaQ1NIEW1dvCNUdTz-YgeTzl21ZNGIwNJ7vMErei1p5TCOTg> does not existYou can find the complete list of possible keys in the documentation. Just search for “Facet” and look at the “details key”.
For your convenience, the most important ones are:
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pattern: allows to define a regular expression which must be met
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totalDigits: allows to define the maximal number of digits of a number
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minLength: allows to define the minimal length of a value
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maxLength: allows to define the maximal length of a value
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minExclusive: allows to define a minimal value which is still invalid
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maxExclusive: allows to define a maximal value which is already invalid
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minInclusive: allows to define a minimal value which is already valid
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maxInclusive: allows to define a maximal value which is still valid
Have fun defining your DataTypes with custom restrictions!