Apex - Function that sends an email of all of the new records of a given type created after a given datetime.

sendNewRecordsEmail.cls

public static boolean sendNewRecordsEmail(String[] toAddresses, String sobjectName, DateTime createdAfter) {
    String strCreatedAfter = createdAfter.formatGMT('yyyy-MM-dd\'T\'HH:mm:ss\'Z\'');

    // Get the count of records after the createdAfter date/time.
    String restSOQL = String.join(
        new String[]{
            'SELECT count(Id) record_count',
            'FROM ' + sobjectName,
            'WHERE CreatedDate > ' + strCreatedAfter
        },
        '\n'
    );
    String origin = URL.getCurrentRequestUrl().toExternalForm().replaceFirst('^(\\w+\\W+[^/]+)[\\s\\S]*$', '$1');
    String restEndpoint = origin + '/services/data/v60.0/query/?q=' + EncodingUtil.urlEncode(restSOQL, 'UTF-8');
    HttpRequest req = new HttpRequest();
    req.setEndpoint(restEndpoint);
    req.setMethod('GET');
    req.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionId());
    req.setHeader('Accept', 'application/json');
    req.setHeader('Content-Type', 'application/json');
    HttpResponse res = (new Http()).send(req);
    // Process the response
    if (res.getStatusCode() != 200) {
        throw new CalloutException(res.getBody());
    }
    Map<String,Object> topLevel = (Map<String,Object>)JSON.deserializeUntyped(res.getBody());
    Object[] records = (Object[])topLevel.get('records');
    Map<String,Object> firstRecord = (Map<String,Object>)records[0];
    Integer recordCount = (Integer)firstRecord.get('record_count');

    // If no records were found return false.
    if (recordCount == 0) return false;

    // Get an array of all of the field names.
    // Use Schema to dynamically retrieve the object's fields
    Schema.SObjectType objType = Schema.getGlobalDescribe().get(sobjectName);
    if (objType == null) {
        throw new QueryException('Object not found: ' + sobjectName);
    }
    Map<String, Schema.SObjectField> fields = objType.getDescribe().fields.getMap();
    String[] fieldNames = new List<String>(fields.keySet());
    String[] fieldLabels = new String[0];
    for (String fieldName : fieldNames) {
        fieldLabels.add(fields.get(fieldName).getDescribe().getLabel());
    }

    // Gets up to 1,000 of the newest records.
    // NOTE:  Only getting up to 1,000 records to try to avoid too big of a
    // footprint when creating the CSV.
    String soql = String.join(
        new String[]{
            'SELECT ' + String.join(fieldNames, ','),
            'FROM ' + sobjectName,
            'WHERE CreatedDate > ' + strCreatedAfter,
            'ORDER BY CreatedDate DESC',
            'LIMIT 1000'
        },
        '\n'
    );
    SObject[] realRecords = Database.query(soql);

    // Create the CSV
    String fileName = sobjectName + '.csv';
    String fileContents = '';
    List<String[]> rows = new List<String[]>();
    rows.add(fieldLabels);
    for (SObject record : realRecords) {
        String[] row = new String[0];
        for (String fieldName : fieldNames) {
            Object value = record.get(fieldName);
            row.add(value == null ? '' : String.valueOf(value));
        }
        rows.add(row);
    }
    Integer colCount = fieldNames.size();
    Pattern p = Pattern.compile('[",\\n\\r]');
    for (Integer rowsLeft = rows.size(); rowsLeft > 0; rowsLeft--) {
        String[] rowValues = rows.remove(0);
        for (Integer colIndex = 0; colIndex < colCount; colIndex++) {
            rowValues[colIndex] = p.matcher(rowValues[colIndex]).find()
                ? '"' + rowValues[colIndex].replaceAll('"', '""') + '"'
                : rowValues[colIndex];
        }
        fileContents += String.join(rowValues, ',') + '\n';
    }

    // Create a new email message
    Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
    // Set the recipient email address
    email.setToAddresses(toAddresses);
    // Set the email subject and body
    email.setSubject('Newest ' + sobjectName + ' Records');
    email.setPlainTextBody(String.join(
        new String[]{
            'This is an automated report from Salesforce informing you that ',
            String.valueOf(recordCount),
            ' record',
            recordCount == 1 ? '' : 's',
            ' were created since ',
            strCreatedAfter,
            '.  The attached CSV is an export of ',
            recordCount > realRecords.size() ? String.valueOf(realRecords.size()) : 'all',
            ' of these records.'
        },
        ''
    ));
    // Attach the file to the email
    Messaging.EmailFileAttachment attachment = new Messaging.EmailFileAttachment();
    attachment.setFileName(fileName);
    attachment.setBody(Blob.valueOf(fileContents));
    email.setFileAttachments(new Messaging.EmailFileAttachment[]{attachment});
    Messaging.sendEmail(new Messaging.SingleEmailMessage[]{email});

    // Since records were found and an email was sent return true.
    return true;
}

~example-run.cls

// Send an email with all of the records created in the last day.
sendNewRecordsEmail(
    new String[]{'[email protected]'},
    'CHC_Callout__c',
    DateTime.now().addDays(-1)
);