How to escape characters in Azure Table queries?

I want to query for rows where a column named message starts with: metric="foo"

I tried encoding = and " with percentage and hex codes but it did not work.

Microsoft documentations says special characters must be encoded but does not tell how: https://learn.microsoft.com/en-us/rest/api/storageservices/querying-tables-and-entities#query-string-encoding

What should the query look like when value being compared contains special characters?

If you're using azure sdk, then the sdk already did the tricky for you.

In my test, I'm using the latest azure table storage sdk Microsoft.Azure.Cosmos.Table, version 1.0.4.

The test code:

    static void Main(string[] args)
    {
        string connstr = "xxxx";
        var storageAccount = CloudStorageAccount.Parse(connstr);
        CloudTableClient tableClient = storageAccount.CreateCloudTableClient();
        CloudTable table = tableClient.GetTableReference("myCustomer123");

        TableQuery<CustomerEntity> query = new TableQuery<CustomerEntity>();

        string myfilter = TableQuery.CombineFilters(TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, "ivan"),
                                  TableOperators.And,
                                  //for metric="foo", like below.                                      
                                  TableQuery.GenerateFilterCondition("PhoneNumber", QueryComparisons.Equal, "metric=\"foo\"")
                                  );

        query.FilterString = myfilter;

        var items = table.ExecuteQuery(query);

        foreach (var item in items)
        {
            Console.WriteLine(item.RowKey);
            Console.WriteLine(item.PhoneNumber);
        }

       Console.WriteLine("*****end******");
       Console.ReadLine();

    }

Test result: