How to search value by key from Map as well as Nested Map

Question

I have a Map as below :-

def map = [
        a:"a",
        b:[f:"f", g:"g"],
        c:"c",
        d:"d",
        e:[h:"h", i:[j:"j"]],
    ]

Here I want to search value by given key. But problem is provided key is single unique key instead of nested key hierarchy as below :-

println map.a
println map.j

Here output as expected :-

a
null

As you can see, I can't get value for j key, I know because this key is not present in root Map but it is present in nested Map. If I do as below :-

println map.e.i.j

It gives me correct output but I don't know this hierarchy of keys.

Is there any way to get value from above map by passing exact key only??

Note :- All keys are always unique in the provided Map.

The easiest would be actually to dont nest maps, or they must nest? — Kamila Szewczyk, Sep 28 '16 at 13:34
@Joel key could be any where root map as well as nest map but all keys would be unique. — Saurabh Gaur, Sep 28 '16 at 13:38
@Joel Yeah,I know..but I don't know how to search value from this map with this key which could be anywhere. Thanks — Saurabh Gaur, Sep 28 '16 at 13:41
@Joel Let's see, may be someone has faced same issue, I also doing research for this task. Thanks — Saurabh Gaur, Sep 28 '16 at 13:45
http://stackoverflow.com/questions/14196454/groovy-find-a-key-in-a-map-and-return-its-value and http://stackoverflow.com/questions/14044614/finding-the-key-in-a-map-given-the-value. These links should help. — Kamila Szewczyk, Sep 28 '16 at 13:47

BalRog · Accepted Answer · 2016-09-28T14:07:15.913

6

Write a simple tree traversal:

def findDeep(Map m, String key) {
    if (m.containsKey(key)) return m[key]
    m.findResult { k, v -> v instanceof Map ? findDeep(v, key) : null }
}

Given your input map, the following test code:

('a'..'k').each { key ->
    println "${key}: ${findDeep(map, key)}"
}

Yields the following results:

a: a
b: [f:f, g:g]
c: c
d: d
e: [h:h, i:[j:j]]
f: f
g: g
h: h
i: [j:j]
j: j
k: null

edited Sep 28 '16 at 14:07

answered Sep 28 '16 at 13:58

BalRog

3,216
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1

If the person who marked this down would be so kind as to comment on the shortcomings, I would appreciate it. – BalRog Sep 28 '16 at 15:08
1

I'm using similar method to get value (by `m.containsValue(value)` ). Appreciate for example. – Marslo Jan 19 '20 at 09:40

How to search value by key from Map as well as Nested Map

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