Question

I am modifying a Json document through code. The Json has array nested items. My code is failing because I believe its not able to handle Json documents where that particular array is empty. How can I check for null or empty arrays and make this code work for only arrays that have data.

store.DatabaseCommands.UpdateByIndex("Raven/DocumentsByEntityName",
new IndexQuery { Query = "Tag:patrons" },
new[]
{
  new PatchRequest
      {
          Type = PatchCommandType.Modify,
          Name = "Privilege",
          Nested = new[]
           {
             new PatchRequest {Type = PatchCommandType.Set, Name="Level",  

             Value="Gold"}, 
           }
       }
}, allowStale: false);

Json document looks like:

    {
             "Privilege": [{
                           "Level": "Gold",
                           "Code": "12312",
                           "EndDate": "12/12/2012"
                          }],
             "Phones":    [{
                           "Cell": "123123",
                           "Home": "9783041284",
                           "Office": "1234123412"
                          }]
             "MiddleInitial":"F"

           }

Some Json docs can look like (notice Privilege is an empty array in this case)

 {
         "Privilege": [],
         "Phones":    [{
                       "Cell": "123123",
                       "Home": "9783041284",
                       "Office": "1234123412"
                      }]
         "MiddleInitial":"F"

       }

Answer 1

The patching command expects the data to be there, so you need to use an index to find the docs that don’t have an empty Privileges list.

First you need an index like this:

public override IndexDefinition CreateIndexDefinition()
{
    return new IndexDefinitionBuilder<Patron>
    {
        Map = docs => from doc in docs
                      where doc.Privileges != null
                      select new { HasPrivileges = doc.Privileges.Count == 0 ? false : true }
    }.ToIndexDefinition(Conventions);
}

Then you only apply the patch to the docs where HasPrivileges = true, like so:

store.DatabaseCommands.UpdateByIndex("PatronByPrivilege",
              //Only apply the patch to Patrons that have a privilege
              new IndexQuery { Query = "HasPrivileges:true" },
                     new[]
                     {
                          new PatchRequest
                          {
                               .........

I’ve created a full code sample, any problems let me know.