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Hi I am writing Azure function trigger to capture changes for cosmosdb. I am facing a basic problem.

In function.json, I would like to keep the below parameters dynamic ( It should be picked from environment variable). The reason is that the same app will be deployed in multiple environments and they may have different database name.

      "databaseName": "CosmosDbName",
      "collectionName": "UserCollectionName",

I tried setting the values in local.settings.json to test it but it failed and didn't pick the values.

Any suggestions ?

Found the solution

      "databaseName": "%CosmosDbName%",
      "collectionName": "%UserCollectionName%",
SunilS
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  • Thanks for your contribution, I have compiled your conclusion, can you mark it as the answer to end this question? This may help others. You can also post the answer yourself, if that, I will delete my answer. ;) – Cindy Pau Mar 18 '20 at 08:32
  • Thanks Bowman. I have accepted your answer. It explains it nicely – SunilS Mar 21 '20 at 13:20

1 Answers1

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Yes, as you finally found, for the string type, you can use the method %% to set dynamic parameters, and then set the corresponding value in the environment variable(locally, it is set in local.settings.json. On Azure, it needs to set in the Configuration.), %% will match the corresponding value. It should be noted that the dynamic setting of %% is only applicable to string type, other types are not.

Set it like this in the function definition section:

  "databaseName": "%CosmosDbName%",
  "collectionName": "%UserCollectionName%",

Then fill in the corresponding key values in the settings.

Cindy Pau
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    Just to add, public documentation of how binding expressions work is here: https://learn.microsoft.com/azure/azure-functions/functions-bindings-expressions-patterns – Matias Quaranta Mar 18 '20 at 15:42