feat(examples): add p/moul/collection

[moul]

Addresses #1467
Related with #3317

[Gno2D2]

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[notJoon]

left some some concerning points. other things are LGTM

[notJoon]

When rollback occurs due to safeGenerateKey call failures or UniqueIndex conflicts, only the _id index of oldObj is currently being restored.

I didn't found a mechanism to restore previously removed entries in other indices. This can lead to inconsistency between the _id index and other indices, may potentially compromising data integrity.

[moul]

What do you think about fa46373?

[notJoon]

I like it 👍

[notJoon]

In the Set function, when inserting data with the CaseInsensitiveIndex option enabled, keys are stored after being converted to lowercase.

if idx.options&CaseInsensitiveIndex != 0 {
	key = strings.ToLower(key)
}

However, it seems that the same processing is missing when removing these keys in the Delete or Update functions.

In this line, the code attempts to directly delete the key obtained from idx.fn(obj) without any coversion process. I think this can lead to a unexpected behaviour which delection or updates don't work properly because the key doesn't match the actual lowercase key stored in the index.

[moul]

aa7c3ae

[moul]

Question for reviewers: API design preference for Get/GetAll

Currently, we have two different return signatures:

• Get(index, key) (interface{}, uint64) - Returns the object and ID separately
• GetAll(index, key) ([]Entry, bool) - Returns entries that contain both object and ID

I'm considering unifying these to always return Entry/[]Entry types:

Get(index, key) *Entry
GetAll(index, key) []Entry

Potential benefits:

1. Consistent return types between Get and GetAll
2. Enables method chaining (e.g., collection.Get("name", "Alice").DoSomething())
3. Clearer relationship between object and its ID
4. No need for multiple return values

Would love to hear thoughts on which API style you prefer and why.

---

Current API:

// Current Get returns (object, id)
obj, id := collection.Get("name", "Alice")

// Current GetAll returns ([]Entry, bool)
entries, ok := collection.GetAll("tags", "developer")

Alternative API:

// Alternative: Get returns Entry (with embedded ID and Obj)
entry := collection.Get("name", "Alice")
if entry != nil {
    // Use entry.ID and entry.Obj
}

// Alternative: GetAll returns []Entry
entries := collection.GetAll("tags", "developer")

[notJoon]

@moul

Question for reviewers: API design preference for Get/GetAll

Alternative API looks good. Along with the benefits listed, it's more intuitive and particularly I like that it feels functional programming styles.

---

edit(@moul): e43e02a

[notJoon]

LGTM 👍