apoc.convert.fromJsonMap

Function APOC Core

apoc.convert.fromJsonMap('{"a":42,"b":"foo","c":[1,2,3]}'[,'json-path', 'path-options'])

Signature

apoc.convert.fromJsonMap(map :: STRING?, path =  :: STRING?, pathOptions = null :: LIST? OF STRING?) :: (MAP?)

Input parameters

Name	Type	Default
map	STRING?	null
path	STRING?
pathOptions	LIST? OF STRING?	[]

Name

Type

Default

map

STRING?

null

path

STRING?

pathOptions

LIST? OF STRING?

[]

Usage Examples

The following converts a JSON map into a Cypher map:

RETURN apoc.convert.fromJsonMap('{"name": "Graph Data Science Library"}') AS output;

Table 1. Results
Output
{name: "Graph Data Science Library"}

We can also use JSON path expressions to extract part of a JSON map. For example, the following extracts the product property from a JSON map and returns a map:

RETURN apoc.convert.fromJsonMap('{"product": {"name": "Bloom"}}', '$.product') AS output;

Table 2. Results
Output
{name: "Bloom"}

If we try to convert a non-map structure, we’ll get an exception. For example:

RETURN apoc.convert.fromJsonMap('[{"name": "Neo4j"}]') AS output;

Table 3. Results
Failed to invoke function `apoc.convert.fromJsonMap`: Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.LinkedHashMap<java.lang.Object,java.lang.Object>` out of START_ARRAY token at [Source: (String)"[{"name": "Neo4j"}]"; line: 1, column: 1]

In this case we should instead use apoc.convert.fromJsonList.

Moreover, we can customize the Json path options, adding as third parameter (pathOptions) a list of strings, where the strings are based on Enum<Option>. The default value is ["SUPPRESS_EXCEPTIONS", "DEFAULT_PATH_LEAF_TO_NULL"]. Note that we can also insert [], that is "without options". So we can execute (with default pathOptions):

RETURN apoc.convert.fromJsonMap('{ "columns": {
      "col2": {
        "_id": "772col2"
      }
    }
}', '$.columns.col2') AS output;

Table 4. Results
output
{ "_id": "772col2" }

or, with custom path options:

RETURN apoc.convert.fromJsonMap('{ "columns": {
      "col2": {
        "_id": "772col2"
      }
    }
}', '$.columns.col2', ['ALWAYS_RETURN_LIST']) AS output;

Table 5. Results
Failed to invoke function `apoc.convert.getJsonPropertyMap`: Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.LinkedHashMap<java.lang.Object,java.lang.Object>` out of START_ARRAY token at [Source: UNKNOWN; line: -1, column: -1]

Also, we could leverage the apoc.json.validate procedure (provided with APOC full) to handle incorrectly formatted JSONs by continuing the execution instead of causing it to fail. For example, the following query returns 0 instead of failing due to InputCoercionException: Numeric value (18446744062065078016838) out of range:

WITH '{
  "foo": ["1", {"bar": 18446744062065078016838}, {"baz":  18446744062065078016838} ],
  "baz": 7
}' as json
CALL { WITH json CALL apoc.json.validate(json) YIELD value RETURN collect(value) AS errs }
RETURN CASE errs WHEN [] THEN apoc.convert.fromJsonMap(json, '$', []) ELSE 0 END AS value