Select

• Path function Select is used to project each item in a collection to another item in a collection.

• Currently we can use project items to calculated values that uses path functions as well as JsonQL expressions (e.g., “e => e.Salary * 2”).

  Note

  Next release will support also more complex projections to create new JSON objects and arrays (e.g., “e => {“Name” : Concatenate(e.FirstName, ‘ ‘, e.LastName)}”, “e => [e.Addresses.Where(a => a.State != ‘CO’)]”, etc.). This improvement will be added based on demand for jsonQL as well as on this feature, since the author might be involved with other things in near future.

Function Parameters

• path:

  • Required: Yes

  • Type: lambda function of type “x => any”

  • Description: A lambda function for projecting a collection item to a valid JsonQL expression.

Example

Note

The following JSON files are referenced in JsonQL expressions in Example.json in example below: Companies.json.

Example.json below demonstrates using Select path function.

{
  "SelectFirstThreeEmployeesAcrossAllCompanies":
    "$value(Companies.Select(c => c.Employees).Where(x => index <= 2))",

  "SelectRaisedSalariesOfFirstThreeEmployeesAcrossAllCompanies":
    "$value(Companies.Select(c => c.Employees).Where(x => index <= 2).Select(e => 2 * e.Salary))",

  "SelectUsingNamedParameter": "$value(Companies.Select(path -> c => c.CompanyData.Name))"
}

The result (i.e., an instance of JsonQL.Compilation.ICompilationResult) is serialized to a Result.json file below.

Note

For brevity, the serialized result includes only serialized evaluated Example.json and does not include parent JSON files in JsonQL.Compilation.ICompilationResult.CompiledJsonFiles

{
  "CompiledJsonFiles":[
    {
      "TextIdentifier": "Example",
      "CompiledParsedValue":
      {
        "SelectFirstThreeEmployeesAcrossAllCompanies": [
          {
            "Id":  100000001,
            "Name":  "John Smith",
            "Address": {
              "Street":  "456 Oak Avenue",
              "City":  "Chicago",
              "State":  "IL",
              "ZipCode":  "60601"
            },
            "Salary":  99500,
            "Age":  45
          },
          {
            "Id":  100000002,
            "Name":  "Alice Johnson",
            "Address": {
              "Street":  "123 Maple Street",
              "City":  "New York",
              "State":  "NY",
              "ZipCode":  "10001"
            },
            "Salary":  105000,
            "Age":  38
          },
          {
            "Id":  100000003,
            "Name":  "Michael Brown",
            "Address": {
              "Street":  "789 Pine Lane",
              "City":  "Los Angeles",
              "State":  "CA",
              "ZipCode":  "90001"
            },
            "Salary":  89000,
            "Age":  50
          }
        ],
        "SelectRaisedSalariesOfFirstThreeEmployeesAcrossAllCompanies": [
          199000,
          210000,
          178000
        ],
        "SelectUsingNamedParameter": [
          "Strange Things, Inc",
          "Sherwood Forest Timber, Inc",
          "Atlantic Transfers, Inc"
        ]
      }
    }
  ],
  "CompilationErrors":
  {
    "$type": "System.Collections.Generic.List`1[[JsonQL.Compilation.ICompilationErrorItem, JsonQL]], System.Private.CoreLib",
    "$values": []
  }
}

The code snippet shows how the JSON file Example.json was parsed using JsonQL.Compilation.IJsonCompiler

// Set the value of jsonCompiler to an instance of JsonQL.Compilation.IJsonCompiler here.
// The value of JsonQL.Compilation.JsonCompiler is normally created by Dependency Injection container
// and it is normally configured as a singleton.
JsonQL.Compilation.IJsonCompiler jsonCompiler = null!;

var sharedExamplesFolderPath = new []
{
    "DocFiles", "MutatingJsonFiles", "Examples"
};

var companiesJsonTextData = new JsonTextData("Companies",
    LoadJsonFileHelpers.LoadJsonFile("Companies.json", sharedExamplesFolderPath));

var result = jsonCompiler.Compile(new JsonTextData("Example",
    this.LoadExampleJsonFile("Example.json"), companiesJsonTextData));