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    <p>I'm the author of Neo4jClient. (The guy who gives his software away for free.)</p> <p>Q1a:</p> <blockquote> <p>"Can I use the CRUD API to look up node A by its ID, create node B from a POCO, create a relationship between A and B"</p> </blockquote> <p>Cypher is the way of not just the future, but also the 'now'.</p> <p>Start with the Cypher (lots of resources for that):</p> <pre><code>START user=node:user(Id: 1234) CREATE user-[:INVITED]-&gt;(user2 { Id: 4567, Name: "Jim" }) Return user2 </code></pre> <p>Then convert it to C#:</p> <pre><code>graphClient.Cypher .Start(new { user = Node.ByIndexLookup("User", "Id", userId) }) .Create("user-[:INVITED]-&gt;(user2 {newUser})") .WithParam("newUser", new User { Id = 4567, Name = "Jim" }) .Return(user2 =&gt; user2.Node&lt;User&gt;()) .Results; </code></pre> <p>There are lots more similar examples here: <a href="https://github.com/Readify/Neo4jClient/wiki/cypher-examples" rel="nofollow">https://github.com/Readify/Neo4jClient/wiki/cypher-examples</a></p> <p>Q1b:</p> <blockquote> <p>" and add B's ID to a legacy index in one request?"</p> </blockquote> <p>No, legacy indexes are not supported in Cypher. If you really want to keep using them, then you should stick with the CRUD API. That's ok: if you want to use legacy indexes, use the legacy API.</p> <p>Q2.</p> <blockquote> <p>"If not, what is the alternative? Is the CRUD API considered legacy code and should we move towards a Cypher-based Neo4j 2.0 approach?"</p> </blockquote> <p>That's exactly what you want to do. Cypher, with labels and automated indexes:</p> <pre><code>// One time op to create the index // Yes, this syntax is a bit clunky in C# for now graphClient.Cypher .Create("INDEX ON :User(Id)") .ExecuteWithoutResults(); // Find an existing user, create a new one, relate them, // and index them, all in a single HTTP call graphClient.Cypher .Match("(user:User)") .Where((User user) =&gt; user.Id == userId) .Create("user-[:INVITED]-&gt;(user2 {newUser})") .WithParam("newUser", new User { Id = 4567, Name = "Jim" }) .ExecuteWithoutResults(); </code></pre> <p>More examples here: <a href="https://github.com/Readify/Neo4jClient/wiki/cypher-examples" rel="nofollow">https://github.com/Readify/Neo4jClient/wiki/cypher-examples</a></p> <p>Q3.</p> <blockquote> <p>"Does this Cypher-based approach mean that we lose POCO-to-node translation for create operations? That was very convenient."</p> </blockquote> <p>Correct. But that's what we collectively all want to do, where Neo4j is going, and where Neo4jClient is going too.</p> <p>Think about SQL for a second (something that I assume you are familiar with). Do you run a query to find the internal identifier of a node, including its file offset on disk, then use this internal identifier in a second query to manipulate it? No. You run a single query that does all that in one hit.</p> <p>Now, a common use case for why people like passing around <code>Node&lt;T&gt;</code> or <code>NodeReference</code> instances is to reduce repetition in queries. This is a legitimate concern, however because the fluent queries in .NET are immutable, we can just construct a base query:</p> <pre><code>public ICypherFluentQuery FindUserById(long userId) { return graphClient.Cypher .Match("(user:User)") .Where((User user) =&gt; user.Id == userId); // Nothing has been executed here: we've just built a query object } </code></pre> <p>Then use it like so:</p> <pre><code>public void DeleteUser(long userId) { FindUserById(userId) .Delete("user") .ExecuteWithoutResults(); } </code></pre> <p>Or, add even more Cypher logic to delete all the relationships too:</p> <p>Then use it like so:</p> <pre><code>public void DeleteUser(long userId) { FindUserById(userId) .Match("user-[:?rel]-()") .Delete("rel, user") .ExecuteWithoutResults(); } </code></pre> <p>This way, you can effectively reuse references, but without ever having to pull them back across the wire in the first place.</p>
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    1. USPhillip Scott Givens
    1. USTatham Oddie
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    1. COMany thanks for this answer. By "POCO-to-node translation", I actually meant that you don't have spell everything out and write, for example, `... create (user { Id=1, FirstName='John', LastName='Doe', BirthDate=...` as a string in your query, but you can use a plain object with properties instead. But I can see that that's covered with the "newUser" param above.
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      1. USJan Van den bosch
    2. COAh yes, I now see that I read your Q3 in the reverse order to what you intended. Alas, it looks like you're on track with everything you need now anyway. CYPHER ALL THE THINGS! :)
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