5. The MQL Write Grammar

5. The MQL Write Grammar: bidirectional links

2008-06-17T22:20:16.0007Z

All links are truly bidirectional. The client may not show them, but that is not the same thing. The Explore view (change view to tools/explore in the URL, or hit F8 to expose the tool bar at the bottom of the page) shows all incoming and outgoing links. Non-reciprocated properties can also be accessed in MQL using the ! operator:

{
"!/music/release/artist" : [
    {
      "name" : null
    }
],
"id" : "/en/the_beatles"
}

5. The MQL Write Grammar: bidirectional links

2008-06-17T21:36:05.0012Z

"One of the fundamental aspects of Metaweb is that all links between nodes are bi-directional."

Is this really true? There are properties that have no reverse property defined, and are in effect unidirectional.

These can be found with the following query:

[
{
    "id" : null,
    "limit" : 10,
    "reverse_property" : {
      "id" : null,
      "optional" : "forbidden"
    },
    "type" : "/type/property"
}
]

5. The MQL Write Grammar: Writing Weblink

2008-06-03T17:50:41.0000Z

The type /common/topic has a property "webpage" that you can use. All topics should include /common/topic as one of the types (although it won't be listed explicitly on the page) -- it's what gives them the images, weblinks, description, and "also known as" properties.

5. The MQL Write Grammar: Writing Weblink

2008-05-31T20:26:55.0012Z

It looks like it isn't possible to use the write service to create weblinks, as it's outside the schema. But maybe I'm wrong.

If we want to establish a link for an object, am I correct in guessing that the schema would need to incorporate a link property?

5. The MQL Write Grammar: Errata

2008-03-25T06:16:32.0000Z

The "creating a domain" section is misleading: the new domain will not have the special permission structure that is usually associated with an instance of /type/domain. The only way to create that permission is to use a special domain creation entrypoint, which should be documented elsewhere rather than as part of the mqlwrite tutorial.

5. The MQL Write Grammar: Errata

2008-03-14T14:47:34.0007Z

5.1.12.1. Creating Self-Referential Reciprocal Properties

At the time of this writing, the freebase.com client does not allow us to create reciprocal properties where both ends of the link refer the same type

This is no longer true.

5. The MQL Write Grammar: Errata

2008-03-14T14:11:11.0000Z

5.1.11. Namespaces

What if we query the id of a note?
We get the guids of the notes rather than the fully-qualified names we've just defined.

This behaviour seems to have changed. I get the fully-quailified names and not the guids as stated above:

  "note":[{"id":"/user/willmoffat/note/C"}
  ... snip ... ]

5. The MQL Write Grammar: Errata

2008-03-14T14:10:28.0012Z

If you spot a mistake in the mqlwrite docs then please reply here.

5. The MQL Write Grammar: Don't forget the {query:{}} envelope!

2008-03-14T14:03:32.0012Z

If you've just started the tutorial, remember that you can't just copy and paste the examples. You need to add the envelope.

So, the first example

{
  "create":"unless_exists",
  ... snip ...
}

Becomes

{"query":
  {
  "create":"unless_exists",
  ... snip ...
   }
}

5. The MQL Write Grammar: help for a simple piece of mqlwrite

2007-07-15T23:59:18.0007Z

{ "query":{ "gender":{ "connect":"update", "id":"#9202a8c04000641f8000000000017b14" }, "id":"#9202a8c04000641f800000000001b3f3", "type":"/people/person" } }

5. The MQL Write Grammar: help for a simple piece of mqlwrite

2007-07-15T19:57:11.0004Z

Suppose I'd like to set George Eliot's gender to 'Female'. I can find an id for her, and another for her gender, with a read query: {"query":{ "gender":[{ "id":null }], "id":null, "key":"George_Eliot", "type":"/people/person" }} But I can't work out how to use this to write her gender in.