How i can add a List to the JSON POST request with webwrite (required for RESTful interface of Neo4j)

The following RESTful JSON Interface is needed to submit a Query (e.g. Node creation) to a Neo4j-Database:

{
  "statements" : [ {
    "statement" : "CREATE (n) RETURN id(n)"
  } ]
}

The JSON-Object is created internal the WEBWRITE-Function. The nested structure can be created in Matlab and is compiled to JSON by the WEBWRITE-Function as well. I was unable to create a JSON List (Array) by using the following approach (Cell Array):

api = 'http://localhost:7474/';
url = [api 'db/data/transaction/commit'];

statem{1,1} = 1;
ab = struct('statement', 'CREATE (n) RETURN id(n)');
statem{1,1} = ab;
statems = struct('statements', statem);

options = weboptions('ContentType','json', 'MediaType','application/json', 'RequestMethod','POST', 'Username', 'neo4j', 'Password', 'test');
data = webwrite(url, statems, options);

JSON-Result created by the function above:

{
  "statements": {
    "statement": "CREATE (n) RETURN id(n)"
  }
}

Is there a way to create a List in the JSON-Object created by WEBWRITE?

Answer 1

[Robert Snoeberger]

To create a JSON Array, you should use a cell array. However, you should be careful when passing a cell array as a value input argument to the function struct [1]. There are a few ways to proceed.

You could avoid the struct function when building the "statements" name-value pair:

>> ab = struct('statement', 'CREATE (n) RETURN id(n)');
>> statems.statements = {ab}

statems = 

      statements: {[1x1 struct]}

>>

You could add an extra pair of curly braces '{}' when the value input argument to struct is a cell array:

>> ab = struct('statement', 'CREATE (n) RETURN id(n)');
>> statems = struct('statements', {{ab}})

statems = 

      statements: {[1x1 struct]}

>>

Just make sure that the display of the variable statems includes a pair of curly braces '{}' around [1x1 struct]:

statems = 

      statements: {[1x1 struct]}

[1] http://www.mathworks.com/help/matlab/ref/struct.html