AWS DynamoDB - Dynamically setting DynamoDBTable in object persistence model

Question

I have a .NET Core 2.0 project using AWSDynamodDb (you can ignore dynamo db here as question is not regarding dynamodDB)

I have the following entity class as:

[DynamoDBTable("TableName")]
public class MyData
{
    [DynamoDBHashKey]
    public string Id{ get; set; }

    public string Name{ get; set; }
}

What I want is the "TableName" - the value passed into the attribute - to be populated from my appSettings.json file.

 {
    "TableName": "NewTable" 
 }

Would it be possible to get this value durring runtime by looking at the key from appSettings file?

--Updated--

I am calling the "MyData" class from my controller as below:

  var response = await context.ScanAsync<MyData>(conditions).GetRemainingAsync();

@gunr2171 Yes I am already using configurations in my application. In Startup as: services.AddSingleton<IConfiguration>(Configuration). And then in my class which requires the key as: IConfiguration _configuration; _configuration["UserId"]. But how can I get it over this class attribute? — aman
– aman, Commented Jul 10, 2018 at 19:23
@gunr2171 should be fine, but what edits are you talking about. I have updated my code, please check. — aman
– aman, Commented Jul 10, 2018 at 19:28
Oh wait, you're talking about trying to change the value of the [DynamoDBTable] attribute using the configuration file? — gunr2171
– gunr2171, Commented Jul 10, 2018 at 19:42
@gunr2171 yeah, I just realized that is what he is trying to do, I'm looking to see if there is anything like the ConfigurationPropertyAttribute decoration that was available in the .NetFramework — Ryan Wilson
– Ryan Wilson, Commented Jul 10, 2018 at 19:43
Thanks for the edit, I should have made it more clear while posting. In MVC controller we could create custom filter/attribute so I was looking something around those lines. The above class is being called in my MVC controller of an API. I just dint wanted to hardcode the attribute values and wanted to see if there is an option to get these from the appSettings.json. — aman
– aman, Commented Jul 11, 2018 at 2:05

aman · Accepted Answer · 2018-11-08 15:18:24Z

8

Just for anyone else who come across I was able to resolve this as below:

Remove the table name from the model.

And then use the below code to set the table name dynamically

    public static DynamoDBOperationConfig GetDynamoDbOperationConfig(string dynamoDbTable)
    {
        DynamoDBOperationConfig config = new DynamoDBOperationConfig() { OverrideTableName = dynamoDbTable };
        return config;
    }

We can call this function whenever we are calling any operation against dynamo db like scan, save, delete etc.

answered Nov 8, 2018 at 15:18

aman

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1 Comment

Karthi Keyan Over a year ago

Hi aman i tried Your Code. But the table is not dynamically loading. I have assumed the code from start GetDynamoDbOperationConfig("MyData"); It did not shows the error. But the table is not inserted. When i give [DynamoDBTable("MyData")] the datas are storing in DynamoDB. I have try to use this code by this way [DynamoDBTable( H ighLevelTableExample.GetDynamoDbOperationConfig(S_tablefieldset))] // s_tablefield set is a string variable. So How do you call the variable dynamically. if you share your code it would helpful for many peoples.

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