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Copy file name to clipboardExpand all lines: docs/standard/attributes/retrieving-information-stored-in-attributes.md
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---
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title: "Retrieving Information Stored in Attributes"
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description: Learn to retrieve information stored in attributes, such as for an attribute instance, many instances for the same scope, & many instances for different scopes.
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ms.date: "03/30/2017"
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ms.date: "08/05/2022"
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ms.custom: devdivchpfy22
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dev_langs:
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- "csharp"
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- "vb"
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# Retrieving Information Stored in Attributes
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Retrieving a custom attribute is a simple process. First, declare an instance of the attribute you want to retrieve. Then, use the <xref:System.Attribute.GetCustomAttribute%2A?displayProperty=nameWithType> method to initialize the new attribute to the value of the attribute you want to retrieve. Once the new attribute is initialized, you simply use its properties to get the values.
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Retrieving a custom attribute is a simple process. First, declare an instance of the attribute you want to retrieve. Then, use the <xref:System.Attribute.GetCustomAttribute%2A?displayProperty=nameWithType> method to initialize the new attribute to the value of the attribute you want to retrieve. Once the new attribute is initialized, you can use its properties to get the values.
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> [!IMPORTANT]
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> This topic describes how to retrieve attributes for code loaded into the execution context. To retrieve attributes for code loaded into the reflection-only context, you must use the <xref:System.Reflection.CustomAttributeData> class, as shown in [How to: Load Assemblies into the Reflection-Only Context](../../framework/reflection-and-codedom/how-to-load-assemblies-into-the-reflection-only-context.md).
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> This article describes how to retrieve attributes for code loaded into the execution context. To retrieve attributes for code loaded into the reflection-only context, you must use the <xref:System.Reflection.CustomAttributeData> class, as shown in [How to: Load Assemblies into the Reflection-Only Context](../../framework/reflection-and-codedom/how-to-load-assemblies-into-the-reflection-only-context.md).
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This section describes the following ways to retrieve attributes:
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## Retrieving a Single Instance of an Attribute
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In the following example, the `DeveloperAttribute` (described in the previous section) is applied to the `MainApp` class on the class level. The `GetAttribute` method uses **GetCustomAttribute** to retrieve the values stored in `DeveloperAttribute` on the class level before displaying them to the console.
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In the following example, the `DeveloperAttribute` (described in the previous section) is applied to the `MainApp` class on the class level. The `GetAttribute` method uses `GetCustomAttribute` to retrieve the values stored in `DeveloperAttribute` on the class level before displaying them to the console.
This program displays the following text when executed.
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The execution of the preceding program displays the following text:
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```console
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The Name Attribute is: Joan Smith.
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The Level Attribute is: 42.
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The Reviewed Attribute is: True.
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```
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If the attribute is not found, the **GetCustomAttribute** method initializes `MyAttribute` to a null value. This example checks `MyAttribute` for such an instance and notifies the user if no attribute is found. If the `DeveloperAttribute`is not found in the class scope, the following message displays to the console.
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If the attribute isn't found, the `GetCustomAttribute` method initializes `MyAttribute` to a null value. This example checks `MyAttribute` for such an instance and notifies the user if the attribute isn't found. If `DeveloperAttribute`isn't found in the class scope, the console displays the following message:
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```console
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The attribute was not found.
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```
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This example assumes that the attribute definition is in the current namespace. Remember to import the namespace in which the attribute definition resides if it is not in the current namespace.
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The preceding example assumes that the attribute definition is in the current namespace. Remember to import the namespace in which the attribute definition resides if it isn't in the current namespace.
## Retrieving Multiple Instances of an Attribute Applied to the Same Scope
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In the previous example, the class to inspect and the specific attribute to find are passed to <xref:System.Attribute.GetCustomAttribute%2A>. That code works well if only one instance of an attribute is applied on the class level. However, if multiple instances of an attribute are applied on the same class level, the **GetCustomAttribute** method does not retrieve all the information. In cases where multiple instances of the same attribute are applied to the same scope, you can use <xref:System.Attribute.GetCustomAttributes%2A?displayProperty=nameWithType> to place all instances of an attribute into an array. For example, if two instances of `DeveloperAttribute` are applied on the class level of the same class, the `GetAttribute` method can be modified to display the information found in both attributes. Remember, to apply multiple attributes on the same level, the attribute must be defined with the **AllowMultiple** property set to **true** in the <xref:System.AttributeUsageAttribute>.
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In the preceding example, the class to inspect and the specific attribute to find are passed to the <xref:System.Attribute.GetCustomAttribute%2A> method. That code works well if only one instance of an attribute is applied on the class level. However, if multiple instances of an attribute are applied on the same class level, the `GetCustomAttribute` method doesn't retrieve all the information. In cases where multiple instances of the same attribute are applied to the same scope, you can use <xref:System.Attribute.GetCustomAttributes%2A?displayProperty=nameWithType>method to place all instances of an attribute into an array. For example, if two instances of `DeveloperAttribute` are applied on the class level of the same class, the `GetAttribute` method can be modified to display the information found in both attributes. Remember, to apply multiple attributes on the same level. The attribute must be defined with the `AllowMultiple` property set to `true` in the <xref:System.AttributeUsageAttribute> class.
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The following code example shows how to use the **GetCustomAttributes** method to create an array that references all instances of `DeveloperAttribute` in any given class. The values of all attributes are then displayed to the console.
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The following code example shows how to use the `GetCustomAttributes` method to create an array that references all instances of `DeveloperAttribute` in any given class. The code then outputs the values of all the attributes to the console.
## Retrieving Multiple Instances of an Attribute Applied to Different Scopes
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The <xref:System.Attribute.GetCustomAttributes%2A> and <xref:System.Attribute.GetCustomAttribute%2A> methods do not search an entire class and return all instances of an attribute in that class. Rather, they search only one specified method or member at a time. If you have a class with the same attribute applied to every member and you want to retrieve the values in all the attributes applied to those members, you must supply every method or member individually to **GetCustomAttributes** and **GetCustomAttribute**.
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The <xref:System.Attribute.GetCustomAttributes%2A> and <xref:System.Attribute.GetCustomAttribute%2A> methods don't search an entire class and return all instances of an attribute in that class. Rather, they search only one specified method or member at a time. If you have a class with the same attribute applied to every member and you want to retrieve the values in all the attributes applied to those members, you must supply every method or member individually to `GetCustomAttributes` and `GetCustomAttribute`.
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The following code example takes a class as a parameter and searches for the `DeveloperAttribute` (defined previously) on the class level and on every individual method of that class.
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The following code example takes a class as a parameter and searches for the `DeveloperAttribute` (defined previously) on the class level and on every individual method of that class:
If no instances of the `DeveloperAttribute` are found on the method level or class level, the `GetAttribute` method notifies the user that no attributes were found and displays the name of the method or class that does not contain the attribute. If an attribute is found, the `Name`, `Level`, and `Reviewed` fields are displayed to the console.
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If no instances of the `DeveloperAttribute` are found on the method level or class level, the `GetAttribute` method notifies the user that no attributes were found and displays the name of the method or class that doesn't contain the attribute. If an attribute is found, the console displays the `Name`, `Level`, and `Reviewed` fields.
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You can use the members of the <xref:System.Type> class to get the individual methods and members in the passed class. This example first queries the **Type** object to get attribute information for the class level. Next, it uses <xref:System.Type.GetMethods%2A?displayProperty=nameWithType> to place instances of all methods into an array of <xref:System.Reflection.MemberInfo?displayProperty=nameWithType> objects to retrieve attribute information for the method level. You can also use the <xref:System.Type.GetProperties%2A?displayProperty=nameWithType> method to check for attributes on the property level or <xref:System.Type.GetConstructors%2A?displayProperty=nameWithType> to check for attributes on the constructor level.
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You can use the members of the <xref:System.Type> class to get the individual methods and members in the passed class. This example first queries the `Type` object to get attribute information for the class level. Next, it uses <xref:System.Type.GetMethods%2A?displayProperty=nameWithType> to place instances of all methods into an array of <xref:System.Reflection.MemberInfo?displayProperty=nameWithType> objects to retrieve attribute information for the method level. You can also use the <xref:System.Type.GetProperties%2A?displayProperty=nameWithType> method to check for attributes on the property level or <xref:System.Type.GetConstructors%2A?displayProperty=nameWithType> to check for attributes on the constructor level.
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