问题
I have some nodes in my neo4j graph that are a combination of multiple entities. On these nodes I have a property named "p_value" that has a type of double[].
I'm merging new entities into existing nodes and with my merge command I'm using on match to push the new p_values onto the end of this double[] array. The issues is that for some of my entities I don't have p_values, so I need to push something like -infinity/infinity, NaN, or NULL into my double[] p_value array.
Here is an example cypher query I've tried.
MERGE (process:GOTERM { name: "immune system process", go_id: 50896})
ON CREATE SET process.som = ["som_mouse_3_2"], process.p_value = [NULL]
ON MATCH SET process.som = process.som + "som_mouse_3_2", process.p_value = process.p_value + NULL;
The issue here is that if I have an existing node with that "name" and "go_id" the p_value property will be deleted when I try to add a NULL value to the existing array of p_values.
回答1:
Do you actually want to have a null value in the array or would it be better to just not touch it in the null case?
How about something like this where you only set p_value if the newPValue is non null?
WITH null AS newPValue
MERGE (process:GOTERM { name: "immune system process", go_id: 50896})
ON CREATE SET process.som = ["som_mouse_3_2"], process.p_value = []
ON MATCH SET process.som = process.som + "som_mouse_3_2",
process.p_value = CASE WHEN newPValue is null THEN process.p_value ELSE process.p_value + newPValue END
RETURN process
来源：https://stackoverflow.com/questions/26980830/how-to-add-infinity-nan-or-null-values-to-a-double-property-on-a-node-in-cyp