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collect() : Extract Property from All Items

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Summary

Extract a specific property from all items in a collection, returning a new array of those property values.

Signature 

collect(collection, propertyName)

Parameters

Parameter Type Required Description
collection Array/Collection Yes The collection of objects
propertyName String Yes Name of the property to extract

Returns

Type: Array

An array containing the values of the specified property from each item.

Examples

Extract Property Values 

<p>Product names: </p>

Data:

doc.Params["model"] = new {
    products = new[] {
        new { name = "Widget A", price = 15.50 },
        new { name = "Widget B", price = 22.00 },
        new { name = "Widget C", price = 8.75 }
    }
};

Output:

<p>Product names: Widget A, Widget B, Widget C</p>

Calculate Total from Property 

<p>Total price: $</p>
<p>Average price: $</p>

Data:

doc.Params["model"] = new {
    items = new[] {
        new { name = "Item A", price = 10.00, quantity = 2 },
        new { name = "Item B", price = 15.50, quantity = 1 },
        new { name = "Item C", price = 8.25, quantity = 3 }
    }
};

Output:

<p>Total price: $33.75</p>
<p>Average price: $11.25</p>

Extract IDs for Display 

<p>Order IDs: </p>
<p>Total orders: </p>

Data:

doc.Params["model"] = new {
    orders = new[] {
        new { id = "ORD001", customer = "Alice", total = 150.00 },
        new { id = "ORD002", customer = "Bob", total = 200.00 },
        new { id = "ORD003", customer = "Charlie", total = 175.50 }
    }
};

Output:

<p>Order IDs: ORD001, ORD002, ORD003</p>
<p>Total orders: 3</p>

Statistical Analysis 

<h3>Sales Performance</h3>
<p>Total sales: $</p>
<p>Average sale: $</p>
<p>Highest sale: $</p>
<p>Lowest sale: $</p>

Data:

doc.Params["model"] = new {
    sales = new[] {
        new { date = "2024-03-01", amount = 1250.00 },
        new { date = "2024-03-02", amount = 1580.50 },
        new { date = "2024-03-03", amount = 1420.00 },
        new { date = "2024-03-04", amount = 1890.25 }
    }
};

Output:

<h3>Sales Performance</h3>
<p>Total sales: $6140.75</p>
<p>Average sale: $1535.19</p>
<p>Highest sale: $1890.25</p>
<p>Lowest sale: $1250</p>

Nested Property Collection 


  <h4></h4>
  <p>Members: </p>
  <p>Total experience:  years</p>

Data:

doc.Params["model"] = new {
    teams = new[] {
        new {
            name = "Development",
            members = new[] {
                new { name = "Alice", yearsExperience = 5 },
                new { name = "Bob", yearsExperience = 3 }
            }
        },
        new {
            name = "Design",
            members = new[] {
                new { name = "Charlie", yearsExperience = 7 },
                new { name = "Diana", yearsExperience = 4 }
            }
        }
    }
};

Output:

<h4>Development</h4>
<p>Members: Alice, Bob</p>
<p>Total experience: 8 years</p>
<h4>Design</h4>
<p>Members: Charlie, Diana</p>
<p>Total experience: 11 years</p>

Notes

  • Returns empty array if collection is null or empty
  • Property must exist on all items (or be null)
  • Case-sensitive property names
  • Does not modify original collection
  • Essential for aggregation operations on object collections
  • Useful for:
    • Extracting values for calculations
    • Creating comma-separated lists
    • Statistical operations on properties
    • Data transformation pipelines
  • Often combined with:
    • sum() - total property values
    • average() - average property values
    • min()/max() - find extremes
    • join() - create delimited string
    • count() - count extracted values
  • Alternative specific functions exist: sumOf(), averageOf(), minOf(), maxOf()

See Also