DocumentMutation.append()

Operations Performed

Checks for the existence of the field that contains the string or array to be appended.

If the field exists, checks the data type.
If the data type matches the data type of the value to append, the value is appended.
If the field does not exist or the data types do not match, the operation fails.

Example of Appending to a String

Original document

{ "_id" : "000001"; "comment" : "Works great!" }

Example code for the append

  public DocumentMutation buildDocumentMutation() {
    return MapRDB.newDocumentMutation()
      .append("comment", " \nUpdate: Still works great!");
  }

  public void update(String tablePath, DocumentMutation mutation, String _id) {
    try(Table table = MapRDB.getTable(tablePath)) {
      table.update(_id, mutation);
    }
  }

Parameter	Description
`_id`	The value of the document's `_id` field.
`tablePath`	The path of the table in the MapR file system. See Table Paths.

Revised document

{ "_id" : "000001"; "comment" : "Works great! \nUpdate: Still works great!" }

Example of Appending to an Array

Original document

{ "_id" : "000001"; "Score" : [10,20] }

Example code for the append

  public DocumentMutation buildDocumentMutation() {
    return MapRDB.newDocumentMutation()
      .append("Score", 30);
  }

  public void update(String tablePath, DocumentMutation mutation, String _id) {
    try(Table table = MapRDB.getTable(tablePath)) {
      table.update(_id, mutation);
    }
  }

Revised document

{ "_id" : "000001"; "Score" : [10,20,30] }

Permissions Required

The readAce and writeAce permissions on the volumes where the JSON tables that contain the documents are located. For information about how to set permissions on volumes, see Setting/Modifying Whole Volume ACEs.
readperm and writeperm on the field to which you are appending the new string or array. See How to Obtain readperm and writeperm on a Field.

Link to Javadoc

DocumentMutation

IMPORTANT: If a DocumentMutation object modifies a field two or more times, only the final operation on that field is applied.

Example One

table.update() in the last line fails with error code 22:

DBDocument doc = MapRDB.newDocument()
        .set("int", 100)
        .set("date", new Date(1000))
        .set("string", "a string");

table.insertOrReplace("doc1", doc);

// Set different fields
DocumentMutation mutation = MapRDB.newDocumentMutation();
mutation.setOrReplace("string", 1000);
mutation.set("string", 2000);

table.update("doc1", mutation);

Example Two

This code results in the document {"string":"a string add3"}, rather than the document {"string":"a string add1 add2 add3"}.

DBDocument doc = MapRDB.newDocument()
        .set("string", "a string");

table.insertOrReplace("doc1", record);

DocumentMutation mutation = MapRDB.newDocumentMutation();
mutation.append("string", " add1");
mutation.append("string", " add2");
mutation.append("string", " add3");

table.update("doc1", mutation);