[Breaking change]: Repeated XML Elements Now Have Index Key in Microsoft.Extensions.Configuration.Xml

[eerhardt]

Description

When Microsoft.Extensions.Configuration.Xml is used to read an XML document that has repeated XML elements without a Name attribute, for example:

<settings>
  <Data ConnectionString="TestConnectionString" />
  <Data Provider="MySql" />
</settings>

-or-

<configuration>
    <Level1>
        <Level2 Key1="Value1" />
        <Level2 Key2="Value2" />
    </Level1>
</configuration>

The Configuration entries created with these repeated elements will now have an index appended to their configuration path.

Version

6.0.0

Version

Other (please put exact version in description textbox)

Previous behavior

The Configurations created from the above XML files were:

Data:ConnectionString = TestConnectionString
Data:Provider = MySql

and

Level1:Level2:Key1 = Value1
Level1:Level2:Key2 = Value2

respectively.

New behavior

The Configurations created from the above XML files are now:

Data:0:ConnectionString = TestConnectionString
Data:1:Provider = MySql

and

Level1:Level2:0:Key1 = Value1
Level1:Level2:1:Key2 = Value2

respectively.

Type of breaking change

• Binary incompatible: Existing binaries may encounter a breaking change in behavior, such as failure to load/execute or different run-time behavior.
• Source incompatible: Source code may encounter a breaking change in behavior when targeting the new runtime/component/SDK, such as compile errors or different run-time behavior.

Reason for change

This change was introduced to fully support repeated XML elements without a Name attribute. The previous behavior only allowed for repeated elements to set unique values (attributes or sub-elements). If repeated XML elements had the same attribute, an exception would be thrown.

Recommended action

1. You can update your XML to collapse the 2 attributes into the same element, and get the original behavior. For example,

<configuration>
    <Level1>
        <Level2 Key1="Value1" Key2="Value2" />
    </Level1>
</configuration>

2. You can update your code to expect 0, 1, 2, etc. indices in the IConfiguration keys.

configRoot.GetSection("Level1:Level2")

becomes

configRoot.GetSection("Level1:Level2:0")

Feature area

Extensions

Affected APIs

https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.configuration.xmlconfigurationextensions
https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.configuration.xml.xmlstreamconfigurationprovider
https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.configuration.xml.xmlconfigurationsource