如何访问Dynamics 365插件中的自定义实体字段

Question

I have the following custom entities with the following fields:

Student:

• Name
• ID
• Average

Course:

• Name
• ID

Participant (Holds a particular Student's score in a particular Course):

• Student (above)
• Course (above)
• Score

I need to create a plugin which upon adding/updating a Participant's score, it updates the Participant's Student's Average accordingly.

So my logic is as follows:

1. Participant is created/updated
2. Loop through all Participants to get the number of courses being taken by the given Participant's Student and sum their scores.
3. Update Participant's Student's Average accordingly.

There are a few things I'm having trouble with:

• Accessing all saved Participants.
• Accessing the Participants Student to first check against all Participants and to update their average.
• Accessing the Student's average (which is essentially the same issue as the previous one).

Anyone who could give me some sample code to help with the aforementioned problems would really be helping me out. Thanks in advance.

Answer 1

You can do query the records in a plugin using Query Expression or FetchXML using service.RetrieveMultiple . For example, you can build the fetchxml using XrmToolBox FetchXML builder or simply download the fetchxml from CRM Advanced find builder and use it in below code sample. Read more

    var fetchXml = $@"
        <fetch>
          <entity name='new_particpiant'>
            <attribute name='new_average'/>
            <filter type='and'>
              <condition attribute='new_particpiant' operator='eq' value='{GUID}'/>
            </filter>
          </entity>
        </fetch>";

    EntityCollection entities = service.RetrieveMultiple(new FetchExpression(fetchXml));

Answer 2

Using Query Expression :

QueryExpression qe = new QueryExpression();
qe.EntityName = "new_particpiant";

ColumnSet columns = new ColumnSet(
new string[1]
{
    "new_average",
});

ConditionExpression ce = new ConditionExpression
{
    AttributeName = "new_particpiant",
    Operator = ConditionOperator.Equal,
    Values = { 'Your Guid' }
};

FilterExpression filterQuery = new FilterExpression();
filterQuery.FilterOperator = LogicalOperator.And;
filterQuery.AddCondition(ce);

qe.ColumnSet = columns;

EntityCollection ec = service.RetrieveMultiple(qe);

Entity data = new Entity();

if (ec.Entities.Count > 0)
{
    data = ec.Entities[0];
    string average = Convert.ToString(data.Attributes["new_average"]);
}